updated from Atlas

02-array-seq/lispy/README.md

@@ -23,4 +23,14 @@ The copyright holder is Peter Norvig and the code is licensed under the
 [MIT license](https://github.com/norvig/pytudes/blob/60168bce8cdfacf57c92a5b2979f0b2e95367753/LICENSE).
 
 
+## Changes to Norvig's code
+
+I made small changes to the programs in `original/`:
+
+* In `lis.py`:
+  * The `Procedure` class accepts a list of expressions as the `body`, and `__call__` evaluates those expressions in order, and returns the value of the last. This is consistent with Scheme's `lambda` syntax and provided a useful example for pattern matching.
+  * In the `elif` block for `'lambda'`, I added the `*` in front of the `*body` variable in the tuple unpacking to capture the expressions as a list, before calling the `Procedure` constructor.
+
+* In `lispy.py` I made [changes and a pull request](https://github.com/norvig/pytudes/pull/106) to make it run on Python 3.
+
 _Luciano Ramalho<br/>June 29, 2021_

04-text-byte/charfinder/README.rst

@@ -58,7 +58,7 @@ Test ``find`` with single result::
 
 Test ``find`` with two results::
 
-    >>> find('chess', 'queen', last=0xFFFF)  # doctest:+NORMALIZE_WHITESPACE
+    >>> find('chess', 'queen', end=0xFFFF)  # doctest:+NORMALIZE_WHITESPACE
     U+2655	♕	WHITE CHESS QUEEN
     U+265B	♛	BLACK CHESS QUEEN
 

04-text-byte/charfinder/cf.py

@@ -2,11 +2,11 @@
 import sys
 import unicodedata
 
-FIRST, LAST = ord(' '), sys.maxunicode              # <1>
+START, END = ord(' '), sys.maxunicode + 1           # <1>
 
-def find(*query_words, first=FIRST, last=LAST):     # <2>
+def find(*query_words, start=START, end=END):       # <2>
     query = {w.upper() for w in query_words}        # <3>
-    for code in range(first, last + 1):
+    for code in range(start, end):
         char = chr(code)                            # <4>
         name = unicodedata.name(char, None)         # <5>
         if name and query.issubset(name.split()):   # <6>

05-data-classes/dataclass/club.py

@@ -1,9 +1,7 @@
 from dataclasses import dataclass, field
 
-
 @dataclass
 class ClubMember:
-
     name: str
     guests: list = field(default_factory=list)
 

05-data-classes/dataclass/club_wrong.py

@@ -3,7 +3,6 @@ from dataclasses import dataclass
 # tag::CLUBMEMBER[]
 @dataclass
 class ClubMember:
-
     name: str
     guests: list = []
 # end::CLUBMEMBER[]

05-data-classes/dataclass/hackerclub.py

@@ -34,9 +34,7 @@ from club import ClubMember
 
 @dataclass
 class HackerClubMember(ClubMember):                         # <1>
-
     all_handles = set()                                     # <2>
-
     handle: str = ''                                        # <3>
 
     def __post_init__(self):

05-data-classes/dataclass/hackerclub_annotated.py

@@ -35,9 +35,7 @@ from club import ClubMember
 
 @dataclass
 class HackerClubMember(ClubMember):
-
     all_handles: ClassVar[set[str]] = set()
-
     handle: str = ''
 
     def __post_init__(self):

05-data-classes/dataclass/resource.py

@@ -32,7 +32,7 @@ from enum import Enum, auto
 from datetime import date
 
 
-class ResourceType(Enum):                              # <1>
+class ResourceType(Enum):  # <1>
     BOOK = auto()
     EBOOK = auto()
     VIDEO = auto()

05-data-classes/meaning/demo_dc.py

@@ -2,7 +2,6 @@ from dataclasses import dataclass
 
 @dataclass
 class DemoDataClass:
-
     a: int           # <1>
     b: float = 1.1   # <2>
     c = 'spam'       # <3>

05-data-classes/meaning/demo_nt.py

@@ -1,7 +1,6 @@
 import typing
 
 class DemoNTClass(typing.NamedTuple):
-
     a: int           # <1>
     b: float = 1.1   # <2>
     c = 'spam'       # <3>

05-data-classes/meaning/demo_plain.py

@@ -1,5 +1,4 @@
 class DemoPlainClass:
-
     a: int           # <1>
     b: float = 1.1   # <2>
     c = 'spam'       # <3>

05-data-classes/typing_namedtuple/coordinates.py

@@ -11,7 +11,6 @@
 from typing import NamedTuple
 
 class Coordinate(NamedTuple):
-
     lat: float
     lon: float
 

05-data-classes/typing_namedtuple/coordinates2.py

@@ -13,8 +13,7 @@ This version has a field with a default value::
 from typing import NamedTuple
 
 class Coordinate(NamedTuple):
-
     lat: float                # <1>
     lon: float
     reference: str = 'WGS84'  # <2>
-# end::COORDINATE[]
+# end::COORDINATE[]

05-data-classes/typing_namedtuple/nocheck_demo.py

@@ -1,7 +1,6 @@
 import typing
 
 class Coordinate(typing.NamedTuple):
-
     lat: float
     lon: float
 

07-1class-func/clip.py

@@ -1,48 +0,0 @@
-"""
-    >>> clip('banana split', 5)
-    'banana'
-    >>> clip('banana split', 6)
-    'banana'
-    >>> clip('banana split', 7)
-    'banana'
-    >>> clip('banana split', 8)
-    'banana'
-    >>> clip('banana split', 11)
-    'banana'
-    >>> clip('banana split', 12)
-    'banana split'
-    >>> clip('banana-split', 3)
-    'banana-split'
-
-Jess' tests:
-
-    >>> text = 'The quick brown fox jumps over the lazy dog.'
-    >>> clip14 = clip(text, max_len=14)
-    >>> clip14
-    'The quick'
-    >>> len(clip14)
-    9
-    >>> clip15 = clip(text, max_len=15)
-    >>> clip15
-    'The quick brown'
-    >>> len(clip15)
-    15
-
-"""
-
-# tag::CLIP[]
-def clip(text, max_len=80):
-    """Return max_len characters clipped at space if possible"""
-    text = text.rstrip()
-    if len(text) <= max_len or ' ' not in text:
-        return text
-    end = len(text)
-    space_at = text.rfind(' ', 0, max_len + 1)
-    if space_at >= 0:
-        end = space_at
-    else:
-        space_at = text.find(' ', max_len)
-        if space_at >= 0:
-            end = space_at
-    return text[:end].rstrip()
-# end::CLIP[]

07-1class-func/clip_introspection.rst

@@ -1,9 +0,0 @@
->>> from clip import clip
->>> clip.__defaults__
-(80,)
->>> clip.__code__  # doctest: +ELLIPSIS
-<code object clip at 0x...>
->>> clip.__code__.co_varnames
-('text', 'max_len', 'end', 'space_at')
->>> clip.__code__.co_argcount
-2

07-1class-func/clip_signature.rst

@@ -1,12 +0,0 @@
->>> from clip import clip
->>> from inspect import signature
->>> sig = signature(clip)
->>> sig
-<Signature (text, max_len=80)>
->>> str(sig)
-'(text, max_len=80)'
->>> for name, param in sig.parameters.items():
-...     print(param.kind, ':', name, '=', param.default)
-...
-POSITIONAL_OR_KEYWORD : text = <class 'inspect._empty'>
-POSITIONAL_OR_KEYWORD : max_len = 80

08-def-type-hints/RPN_calc/calc.py

@@ -1,67 +0,0 @@
-#!/usr/bin/env python3
-
-import sys
-from array import array
-from typing import Mapping, MutableSequence, Callable, Iterable, Union, Any
-
-
-OPERATORS: Mapping[str, Callable[[float, float], float]] = {
-    '+': lambda a, b: a + b,
-    '-': lambda a, b: a - b,
-    '*': lambda a, b: a * b,
-    '/': lambda a, b: a / b,
-    '^': lambda a, b: a ** b,
-}
-
-
-Stack = MutableSequence[float]
-
-
-def parse_token(token: str) -> Union[str, float]:
-    try:
-        return float(token)
-    except ValueError:
-        return token
-
-
-def evaluate(tokens: Iterable[str], stack: Stack) -> None:
-    for token in tokens:
-        atom = parse_token(token)
-        if isinstance(atom, float):
-            stack.append(atom)
-        else:  # not float, must be operator
-            op = OPERATORS[atom]
-            x, y = stack.pop(), stack.pop()
-            result = op(y, x)
-            stack.append(result)
-
-
-def display(s: Stack) -> str:
-    items = (repr(n) for n in s)
-    return ' │ '.join(items) + ' →'
-
-
-def repl(input_fn: Callable[[Any], str] = input) -> None:
-    """Read-Eval-Print-Loop"""
-
-    print('Use CTRL+C to quit.', file=sys.stderr)
-    stack: Stack = array('d')
-
-    while True:
-        try:
-            line = input_fn('> ')              # Read
-        except (EOFError, KeyboardInterrupt):
-            break
-        try:
-            evaluate(line.split(), stack)      # Eval
-        except IndexError:
-            print('*** Not enough arguments.', file=sys.stderr)
-        except KeyError as exc:
-            print('*** Unknown operator:', exc.args[0], file=sys.stderr)
-        print(display(stack))                  # Print
-
-    print()
-
-
-if __name__ == '__main__':
-    repl()

08-def-type-hints/RPN_calc/calc_test.py

@@ -1,51 +0,0 @@
-from pytest import mark, approx  # type: ignore
-
-from dialogue import Dialogue  # type: ignore
-
-from calc import evaluate, repl, display, Stack
-
-TOLERANCE = .0001
-
-@mark.parametrize("source, want", [
-    ('2', 2),
-    ('2 3 +', 5),
-    ('5 3 -', 2),
-    ('3 5 * 2 +', 17),
-    ('2 3 4 5 * * *', 120),
-    ('1.1 1.1 1.1 + +', approx(3.3, TOLERANCE)),
-    ('100 32 - 5 * 9 /', approx(37.78, TOLERANCE)),
-])
-def test_evaluate(source, want) -> None:
-    stack: Stack = []
-    evaluate(source.split(), stack)
-    assert want == stack[-1]
-
-
-@mark.parametrize("value, want", [
-    ([], ' →'),
-    ([3.], '3.0 →'),
-    ([3., 4., 5.], '3.0 │ 4.0 │ 5.0 →'),
-])
-def test_display(value, want) -> None:
-    assert want == display(value)
-
-
-@mark.parametrize("session", [
-    """
-    > 3
-    3.0 →
-    """,
-    """
-    > 3 5 6
-    3.0 │ 5.0 │ 6.0 →
-    > *
-    3.0 │ 30.0 →
-    > -
-    -27.0 →
-    """,
-])
-def test_repl(capsys, session) -> None:
-    dlg = Dialogue(session)
-    repl(dlg.fake_input)
-    captured = capsys.readouterr()
-    assert dlg.session.strip() == captured.out.strip()

08-def-type-hints/charindex.py

@@ -15,7 +15,7 @@ characters which contain that word in their names. For example::
 import sys
 import re
 import unicodedata
-from typing import Dict, Set, Iterator
+from collections.abc import Iterator
 
 RE_WORD = re.compile(r'\w+')
 STOP_CODE = sys.maxunicode + 1
@@ -25,8 +25,8 @@ def tokenize(text: str) -> Iterator[str]:  # <1>
     for match in RE_WORD.finditer(text):
         yield match.group().upper()
 
-def name_index(start: int = 32, end: int = STOP_CODE) -> Dict[str, Set[str]]:
+def name_index(start: int = 32, end: int = STOP_CODE) -> dict[str, set[str]]:
-    index: Dict[str, Set[str]] = {}  # <2>
+    index: dict[str, set[str]] = {}  # <2>
     for char in (chr(i) for i in range(start, end)):
         if name := unicodedata.name(char, ''):  # <3>
             for word in tokenize(name):

08-def-type-hints/colors.py

@@ -1,4 +1,4 @@
-from typing import Tuple, Mapping
+from collections.abc import Mapping
 
 NAMES = {
     'aqua': 65535,
@@ -19,7 +19,7 @@ NAMES = {
     'yellow': 16776960,
 }
 
-def rgb2hex(color=Tuple[int, int, int]) -> str:
+def rgb2hex(color: tuple[int, int, int]) -> str:
     if any(c not in range(256) for c in color):
         raise ValueError('Color components must be in range(256)')
     values = (f'{n % 256:02x}' for n in color)
@@ -27,7 +27,7 @@ def rgb2hex(color=Tuple[int, int, int]) -> str:
 
 HEX_ERROR = "Color must use format '#0099ff', got: {!r}"
 
-def hex2rgb(color=str) -> Tuple[int, int, int]:
+def hex2rgb(color: str) -> tuple[int, int, int]:
     if len(color) != 7 or color[0] != '#':
         raise ValueError(HEX_ERROR.format(color))
     try:

08-def-type-hints/columnize.py

@@ -1,7 +1,7 @@
 # tag::COLUMNIZE[]
-from typing import Sequence, List, Tuple
+from collections.abc import Sequence
 
-def columnize(sequence: Sequence[str], num_columns: int = 0) -> List[Tuple[str, ...]]:
+def columnize(sequence: Sequence[str], num_columns: int = 0) -> list[tuple[str, ...]]:
     if num_columns == 0:
         num_columns = round(len(sequence) ** .5)
     num_rows, reminder = divmod(len(sequence), num_columns)

08-def-type-hints/columnize2.py

@@ -1,35 +0,0 @@
-from typing import Sequence, List, Tuple, TypeVar
-
-T = TypeVar('T')
-
-def columnize(sequence: Sequence[T], num_columns: int = 0) -> List[Tuple[T, ...]]:
-    if num_columns == 0:
-        num_columns = round(len(sequence) ** .5)
-    num_rows, reminder = divmod(len(sequence), num_columns)
-    num_rows += bool(reminder)
-    return [tuple(sequence[i::num_rows]) for i in range(num_rows)]
-
-
-def demo() -> None:
-    nato = ('Alfa Bravo Charlie Delta Echo Foxtrot Golf Hotel India'
-            ' Juliett Kilo Lima Mike November Oscar Papa Quebec Romeo'
-            ' Sierra Tango Uniform Victor Whiskey X-ray Yankee Zulu'
-            ).split()
-
-    for line in columnize(nato):
-        for word in line:
-            print(f'{word:15}', end='')
-        print()
-
-    print()
-    for length in range(2, 21, 6):
-        values = list(range(1, length + 1))
-        for row in columnize(values):
-            for cell in row:
-                print(f'{cell:5}', end='')
-            print()
-        print()
-
-
-if __name__ == '__main__':
-    demo()

08-def-type-hints/columnize_alias.py

@@ -1,26 +0,0 @@
-from typing import Sequence, List, Tuple
-
-Row = Tuple[str, ...]
-
-def columnize(sequence: Sequence[str], num_columns: int) -> List[Row]:
-    if num_columns == 0:
-        num_columns = round(len(sequence) ** .5)
-    num_rows, reminder = divmod(len(sequence), num_columns)
-    num_rows += bool(reminder)
-    return [tuple(sequence[i::num_rows]) for i in range(num_rows)]
-
-
-def demo() -> None:
-    nato = ('Alfa Bravo Charlie Delta Echo Foxtrot Golf Hotel India'
-            ' Juliett Kilo Lima Mike November Oscar Papa Quebec Romeo'
-            ' Sierra Tango Uniform Victor Whiskey X-ray Yankee Zulu'
-            ).split()
-
-    for row in columnize(nato, 4):
-        for word in row:
-            print(f'{word:15}', end='')
-        print()
-
-
-if __name__ == '__main__':
-    demo()

08-def-type-hints/comparable/top.py

@@ -20,11 +20,14 @@ Example:
 """
 
 # tag::TOP[]
-from typing import TypeVar, Iterable, List
+from collections.abc import Iterable
+from typing import TypeVar
+
 from comparable import SupportsLessThan
 
 LT = TypeVar('LT', bound=SupportsLessThan)
 
-def top(series: Iterable[LT], length: int) -> List[LT]:
+def top(series: Iterable[LT], length: int) -> list[LT]:
-    return sorted(series, reverse=True)[:length]
+    ordered = sorted(series, reverse=True)
+    return ordered[:length]
 # end::TOP[]

08-def-type-hints/comparable/top_test.py

@@ -1,6 +1,11 @@
-from typing import Tuple, List, Iterator, TYPE_CHECKING
+# tag::TOP_IMPORT[]
-import pytest # type: ignore
+from collections.abc import Iterator
+from typing import TYPE_CHECKING  # <1>
+
+import pytest
+
 from top import top
+# end::TOP_IMPORT[]
 
 @pytest.mark.parametrize('series, length, expected', [
     ((1, 2, 3), 2, [3, 2]),
@@ -8,9 +13,9 @@ from top import top
     ((3, 3, 3), 1, [3]),
 ])
 def test_top(
-    series: Tuple[float, ...],
+    series: tuple[float, ...],
     length: int,
-    expected: List[float],
+    expected: list[float],
 ) -> None:
     result = top(series, length)
     assert expected == result
@@ -18,13 +23,13 @@ def test_top(
 # tag::TOP_TEST[]
 def test_top_tuples() -> None:
     fruit = 'mango pear apple kiwi banana'.split()
-    series: Iterator[Tuple[int, str]] = (
+    series: Iterator[tuple[int, str]] = (  # <2>
         (len(s), s) for s in fruit)
     length = 3
     expected = [(6, 'banana'), (5, 'mango'), (5, 'apple')]
     result = top(series, length)
-    if TYPE_CHECKING:
+    if TYPE_CHECKING:  # <3>
-        reveal_type(series)
+        reveal_type(series)  # <4>
         reveal_type(expected)
         reveal_type(result)
     assert result == expected
@@ -34,7 +39,7 @@ def test_top_objects_error() -> None:
     series = [object() for _ in range(4)]
     if TYPE_CHECKING:
         reveal_type(series)
-    with pytest.raises(TypeError) as exc:
+    with pytest.raises(TypeError) as excinfo:
-        top(series, 3)
+        top(series, 3)  # <5>
-    assert "'<' not supported" in str(exc)
+    assert "'<' not supported" in str(excinfo.value)
 # end::TOP_TEST[]

08-def-type-hints/coordinates/coordinates.py

@@ -8,10 +8,10 @@
 """
 
 # tag::GEOHASH[]
-from geolib import geohash as gh  # type: ignore
+from geolib import geohash as gh  # type: ignore  # <1>
 
 PRECISION = 9
 
-def geohash(lat_lon: tuple[float, float]) -> str:
+def geohash(lat_lon: tuple[float, float]) -> str:  # <2>
     return gh.encode(*lat_lon, PRECISION)
 # end::GEOHASH[]

08-def-type-hints/coordinates/coordinates_named.py

@@ -9,7 +9,7 @@
 """
 
 # tag::GEOHASH[]
-from typing import Tuple, NamedTuple
+from typing import NamedTuple
 
 from geolib import geohash as gh  # type: ignore
 
@@ -21,16 +21,21 @@ class Coordinate(NamedTuple):
 
 def geohash(lat_lon: Coordinate) -> str:
     return gh.encode(*lat_lon, PRECISION)
+# end::GEOHASH[]
 
-def display(lat_lon: Tuple[float, float]) -> str:
+# tag::DISPLAY[]
+def display(lat_lon: tuple[float, float]) -> str:
     lat, lon = lat_lon
     ns = 'N' if lat >= 0 else 'S'
     ew = 'E' if lon >= 0 else 'W'
     return f'{abs(lat):0.1f}°{ns}, {abs(lon):0.1f}°{ew}'
-
+# end::DISPLAY[]
-# end::GEOHASH[]
 
 def demo():
     shanghai = 31.2304, 121.4737
+    print(display(shanghai))
     s = geohash(shanghai)
     print(s)
+
+if __name__ == '__main__':
+    demo()

08-def-type-hints/list.py

@@ -1,10 +0,0 @@
-from typing import List, Tuple
-
-def tokenize(text: str) -> List[str]:
-    return text.upper().split()
-
-l: List[str] = []
-l.append(1)
-print(l)
-
-t: Tuple[str, float] = ('São Paulo', 12_176_866)

08-def-type-hints/messages/hints_1/messages.py

@@ -5,16 +5,15 @@
 >>> show_count(1, 'bird')
 '1 bird'
 >>> show_count(0, 'bird')
-'no bird'
+'no birds'
 
 # end::SHOW_COUNT_DOCTEST[]
 """
 
 # tag::SHOW_COUNT[]
 def show_count(count: int, word: str) -> str:
-    if count == 0:
+    if count == 1:
-        return f'no {word}'
+        return f'1 {word}'
-    elif count == 1:
+    count_str = str(count) if count else 'no'
-        return f'{count} {word}'
+    return f'{count_str} {word}s'
-    return f'{count} {word}s'
 # end::SHOW_COUNT[]

08-def-type-hints/messages/hints_1/messages_test.py

@@ -7,11 +7,11 @@ from messages import show_count
     (1, '1 part'),
     (2, '2 parts'),
 ])
-def test_show_count(qty, expected):
+def test_show_count(qty: int, expected: str) -> None:
     got = show_count(qty, 'part')
     assert got == expected
 
 
 def test_show_count_zero():
     got = show_count(0, 'part')
-    assert got == 'no part'
+    assert got == 'no parts'

08-def-type-hints/messages/hints_2/messages.py

@@ -4,21 +4,22 @@
 >>> show_count(1, 'bird')
 '1 bird'
 >>> show_count(0, 'bird')
-'no bird'
+'no birds'
 >>> show_count(3, 'virus', 'viruses')
 '3 viruses'
+>>> show_count(1, 'virus', 'viruses')
+'1 virus'
+>>> show_count(0, 'virus', 'viruses')
+'no viruses'
 """
 
 # tag::SHOW_COUNT[]
 def show_count(count: int, singular: str, plural: str = '') -> str:
-    if count == 0:
+    if count == 1:
-        return f'no {singular}'
-    elif count == 1:
         return f'1 {singular}'
-    else:
+    count_str = str(count) if count else 'no'
-        if plural:
+    if not plural:
-            return f'{count} {plural}'
+        plural = singular + 's'
-        else:
+    return f'{count_str} {plural}'
-            return f'{count} {singular}s'
 
 # end::SHOW_COUNT[]

08-def-type-hints/messages/hints_2/messages_test.py

@@ -1,4 +1,4 @@
-from pytest import mark  # type: ignore
+from pytest import mark
 
 from messages import show_count
 
@@ -6,9 +6,9 @@ from messages import show_count
 @mark.parametrize('qty, expected', [
     (1, '1 part'),
     (2, '2 parts'),
-    (0, 'no part'),
+    (0, 'no parts'),
 ])
-def test_show_count(qty, expected):
+def test_show_count(qty: int, expected: str) -> None:
     got = show_count(qty, 'part')
     assert got == expected
 
@@ -17,9 +17,9 @@ def test_show_count(qty, expected):
 @mark.parametrize('qty, expected', [
     (1, '1 child'),
     (2, '2 children'),
-    (0, 'no child'),
+    (0, 'no children'),
 ])
-def test_irregular(qty, expected) -> None:
+def test_irregular(qty: int, expected: str) -> None:
     got = show_count(qty, 'child', 'children')
     assert got == expected
 # end::TEST_IRREGULAR[]

08-def-type-hints/messages/no_hints/messages.py

@@ -5,16 +5,15 @@
 >>> show_count(1, 'bird')
 '1 bird'
 >>> show_count(0, 'bird')
-'no bird'
+'no birds'
 
 # end::SHOW_COUNT_DOCTEST[]
 """
 
 # tag::SHOW_COUNT[]
 def show_count(count, word):
-    if count == 0:
+    if count == 1:
-        return f'no {word}'
+        return f'1 {word}'
-    elif count == 1:
+    count_str = str(count) if count else 'no'
-        return f'{count} {word}'
+    return f'{count_str} {word}s'
-    return f'{count} {word}s'
 # end::SHOW_COUNT[]

08-def-type-hints/messages/no_hints/messages_test.py

@@ -12,4 +12,4 @@ def test_show_count(qty, expected):
 
 def test_show_count_zero():
     got = show_count(0, 'part')
-    assert got == 'no part'
+    assert got == 'no parts'

08-def-type-hints/mode/mode_T.py

@@ -1,26 +0,0 @@
-from collections import Counter
-from typing import Iterable, TypeVar
-
-T = TypeVar('T')
-
-def mode(data: Iterable[T]) -> T:
-    data = iter(data)
-    pairs = Counter(data).most_common(1)
-    if len(pairs) == 0:
-        raise ValueError('no mode for empty data')
-    return pairs[0][0]
-
-
-def demo() -> None:
-    from typing import TYPE_CHECKING
-    pop: list[set] = [set(), set()]
-    m = mode(pop)
-    if TYPE_CHECKING:
-        reveal_type(pop)
-        reveal_type(m)
-    print(pop)
-    print(repr(m), type(m))
-
-
-if __name__ == '__main__':
-    demo()

08-def-type-hints/mode/mode_float.py

@@ -1,6 +1,6 @@
 # tag::MODE_FLOAT[]
 from collections import Counter
-from typing import Iterable
+from collections.abc import Iterable
 
 def mode(data: Iterable[float]) -> float:
     pairs = Counter(data).most_common(1)
@@ -20,4 +20,4 @@ def demo() -> None:
     print(repr(m), type(m))
 
 if __name__ == '__main__':
-    demo()
+    demo()

08-def-type-hints/mode/mode_hashable.py

@@ -1,6 +1,7 @@
 # tag::MODE_HASHABLE_T[]
 from collections import Counter
-from typing import Iterable, Hashable, TypeVar
+from collections.abc import Iterable, Hashable
+from typing import TypeVar
 
 HashableT = TypeVar('HashableT', bound=Hashable)
 

08-def-type-hints/mode/mode_hashable_wrong.py

@@ -1,24 +0,0 @@
-# tag::MODE_FLOAT[]
-from collections import Counter
-from typing import Iterable, Hashable
-
-def mode(data: Iterable[Hashable]) -> Hashable:
-    data = iter(data)
-    pairs = Counter(data).most_common(1)
-    if len(pairs) == 0:
-        raise ValueError('no mode for empty data')
-    return pairs[0][0]
-# end::MODE_FLOAT[]
-
-def demo() -> None:
-    import typing
-    pop = 'abracadabra'
-    m = mode(pop)
-    if typing.TYPE_CHECKING:
-        reveal_type(pop)
-        reveal_type(m)
-    print(pop)
-    print(m.upper(), type(m))
-
-if __name__ == '__main__':
-    demo()

08-def-type-hints/mode/mode_number.py

@@ -1,26 +0,0 @@
-from collections import Counter
-from typing import Iterable, TypeVar
-from decimal import Decimal
-from fractions import Fraction
-
-NumberT = TypeVar('NumberT', float, Decimal, Fraction)
-
-def mode(data: Iterable[NumberT]) -> NumberT:
-    pairs = Counter(data).most_common(1)
-    if len(pairs) == 0:
-        raise ValueError('no mode for empty data')
-    return pairs[0][0]
-
-
-def demo() -> None:
-    from typing import TYPE_CHECKING
-    pop = [Fraction(1, 2), Fraction(1, 3), Fraction(1, 4), Fraction(1, 2)]
-    m = mode(pop)
-    if TYPE_CHECKING:
-        reveal_type(pop)
-        reveal_type(m)
-    print(pop)
-    print(repr(m), type(m))
-
-if __name__ == '__main__':
-    demo()

08-def-type-hints/mypy.ini

@@ -1,6 +1,4 @@
 [mypy]
-python_version = 3.8
+python_version = 3.9
 warn_unused_configs = True
 disallow_incomplete_defs = True
-[mypy-pytest]
-ignore_missing_imports = True

08-def-type-hints/passdrill.py

@@ -1,101 +0,0 @@
-#!/usr/bin/env python3
-
-"""passdrill: typing drills for practicing passphrases
-"""
-
-import os
-import sys
-from base64 import b64encode, b64decode
-from getpass import getpass
-from hashlib import scrypt
-from typing import Sequence, Tuple
-
-HASH_FILENAME = 'passdrill.hash'
-HELP = 'Use -s to save passphrase hash for practice.'
-
-
-def prompt() -> str:
-    print('WARNING: the passphrase WILL BE SHOWN so that you can check it!')
-    confirmed = ''
-    while confirmed != 'y':
-        passphrase = input('Type passphrase to hash (it will be echoed): ')
-        if passphrase in ('', 'q'):
-            print('ERROR: the passphrase cannot be empty or "q".')
-            continue
-        print(f'Passphrase to be hashed -> {passphrase}')
-        confirmed = input('Confirm (y/n): ').lower()
-    return passphrase
-
-
-def crypto_hash(salt: bytes, passphrase: str) -> bytes:
-    octets = passphrase.encode('utf-8')
-    # Recommended parameters for interactive logins as of 2017:
-    # N=32768, r=8 and p=1 (https://godoc.org/golang.org/x/crypto/scrypt)
-    return scrypt(octets, salt=salt, n=32768, r=8, p=1, maxmem=2 ** 26)
-
-
-def build_hash(passphrase: str) -> bytes:
-    salt = os.urandom(32)
-    payload = crypto_hash(salt, passphrase)
-    return b64encode(salt) + b':' + b64encode(payload)
-
-
-def save_hash() -> None:
-    salted_hash = build_hash(prompt())
-    with open(HASH_FILENAME, 'wb') as fp:
-        fp.write(salted_hash)
-    print(f'Passphrase hash saved to {HASH_FILENAME}')
-
-
-def load_hash() -> Tuple[bytes, bytes]:
-    try:
-        with open(HASH_FILENAME, 'rb') as fp:
-            salted_hash = fp.read()
-    except FileNotFoundError:
-        print('ERROR: passphrase hash file not found.', HELP)
-        # "standard" exit status codes:
-        # https://stackoverflow.com/questions/1101957/are-there-any-standard-exit-status-codes-in-linux/40484670#40484670
-        sys.exit(74)  # input/output error
-
-    salt, stored_hash = salted_hash.split(b':')
-    return b64decode(salt), b64decode(stored_hash)
-
-
-def practice() -> None:
-    salt, stored_hash = load_hash()
-    print('Type q to end practice.')
-    turn = 0
-    correct = 0
-    while True:
-        turn += 1
-        response = getpass(f'{turn}:')
-        if response == '':
-            print('Type q to quit.')
-            turn -= 1  # don't count this response
-            continue
-        elif response == 'q':
-            turn -= 1  # don't count this response
-            break
-        if crypto_hash(salt, response) == stored_hash:
-            correct += 1
-            answer = 'OK'
-        else:
-            answer = 'wrong'
-        print(f'  {answer}\thits={correct}\tmisses={turn-correct}')
-
-    if turn:
-        print(f'\n{turn} turns. {correct / turn:.1%} correct.')
-
-
-def main(argv: Sequence[str]) -> None:
-    if len(argv) < 2:
-        practice()
-    elif len(argv) == 2 and argv[1] == '-s':
-        save_hash()
-    else:
-        print('ERROR: invalid argument.', HELP)
-        sys.exit(2)  # command line usage error
-
-
-if __name__ == '__main__':
-    main(sys.argv)

08-def-type-hints/replacer.py

@@ -13,9 +13,9 @@
 """
 
 # tag::ZIP_REPLACE[]
-from typing import Iterable, Tuple
+from collections.abc import Iterable
 
-FromTo = Tuple[str, str]  # <1>
+FromTo = tuple[str, str]  # <1>
 
 def zip_replace(text: str, changes: Iterable[FromTo]) -> str:  # <2>
     for from_, to in changes:

08-def-type-hints/replacer2.py

@@ -1,39 +0,0 @@
-"""
-``zip_replace`` replaces multiple calls to ``str.replace``::
-
-    >>> changes = [
-    ...     ('(', ' ( '),
-    ...     (')', ' ) '),
-    ...     ('  ', ' '),
-    ... ]
-    >>> expr = '(+ 2 (* 3 7))'
-    >>> zip_replace(expr, changes)
-    ' ( + 2 ( * 3 7 ) ) '
-
-"""
-
-from typing import Iterable, NamedTuple
-
-
-class FromTo(NamedTuple):
-    from_: str
-    to: str
-
-
-def zip_replace(text: str, changes: Iterable[FromTo], count: int = -1) -> str:
-    for from_, to in changes:
-        text = text.replace(from_, to, count)
-    return text
-
-
-def demo() -> None:
-    import doctest
-    failed, count = doctest.testmod()
-    print(f'{count-failed} of {count} doctests OK')
-    l33t = [FromTo(*p) for p in 'a4 e3 i1 o0'.split()]
-    text = 'mad skilled noob powned leet'
-    print(zip_replace(text, l33t))
-
-
-if __name__ == '__main__':
-    demo()

08-def-type-hints/reveal_array.py

@@ -1,8 +0,0 @@
-from array import array
-from typing import MutableSequence
-
-a = array('d')
-reveal_type(a)
-b: MutableSequence[float] = array('b')
-reveal_type(b)
-

08-def-type-hints/sample.py

@@ -1,10 +1,11 @@
 # tag::SAMPLE[]
+from collections.abc import Sequence
 from random import shuffle
-from typing import Sequence, List, TypeVar
+from typing import TypeVar
 
 T = TypeVar('T')
 
-def sample(population: Sequence[T], size: int) -> List[T]:
+def sample(population: Sequence[T], size: int) -> list[T]:
     if size < 1:
         raise ValueError('size must be >= 1')
     result = list(population)

08-def-type-hints/typevar_bounded.py

@@ -0,0 +1,11 @@
+from typing import TypeVar, TYPE_CHECKING
+
+BT = TypeVar('BT', bound=float)
+
+def triple2(a: BT) -> BT:
+    return a * 3
+
+res2 = triple2(2)
+
+if TYPE_CHECKING:
+    reveal_type(res2)

08-def-type-hints/typevars_constrained.py

@@ -7,7 +7,7 @@ RT = TypeVar('RT', float, Decimal)
 def triple1(a: RT) -> RT:
     return a * 3
 
-res1 = triple1(1, 2)
+res1 = triple1(2)
 
 if TYPE_CHECKING:
     reveal_type(res1)
@@ -19,7 +19,7 @@ BT = TypeVar('BT', bound=float)
 def triple2(a: BT) -> BT:
     return a * 3
 
-res2 = triple2(1, 2)
+res2 = triple2(2)
 
 if TYPE_CHECKING:
     reveal_type(res2)

09-closure-deco/clock/clockdeco_demo.py

@@ -1,17 +1,14 @@
 import time
-from clockdeco import clock
+from clockdeco0 import clock
-
 
 @clock
 def snooze(seconds):
     time.sleep(seconds)
 
-
 @clock
 def factorial(n):
     return 1 if n < 2 else n*factorial(n-1)
 
-
 if __name__ == '__main__':
     print('*' * 40, 'Calling snooze(.123)')
     snooze(.123)

10-dp-1class-func/classic_strategy.py

@@ -6,20 +6,20 @@
 
     >>> joe = Customer('John Doe', 0)  # <1>
     >>> ann = Customer('Ann Smith', 1100)
-    >>> cart = [LineItem('banana', 4, .5),  # <2>
+    >>> cart = (LineItem('banana', 4, Decimal('.5')),  # <2>
-    ...         LineItem('apple', 10, 1.5),
+    ...         LineItem('apple', 10, Decimal('1.5')),
-    ...         LineItem('watermelon', 5, 5.0)]
+    ...         LineItem('watermelon', 5, Decimal(5)))
     >>> Order(joe, cart, FidelityPromo())  # <3>
     <Order total: 42.00 due: 42.00>
     >>> Order(ann, cart, FidelityPromo())  # <4>
     <Order total: 42.00 due: 39.90>
-    >>> banana_cart = [LineItem('banana', 30, .5),  # <5>
+    >>> banana_cart = (LineItem('banana', 30, Decimal('.5')),  # <5>
-    ...                LineItem('apple', 10, 1.5)]
+    ...                LineItem('apple', 10, Decimal('1.5')))
     >>> Order(joe, banana_cart, BulkItemPromo())  # <6>
     <Order total: 30.00 due: 28.50>
-    >>> big_cart = [LineItem(str(item_code), 1, 1.0) # <7>
+    >>> long_cart = tuple(LineItem(str(sku), 1, Decimal(1)) # <7>
-    ...               for item_code in range(10)]
+    ...                  for sku in range(10))
-    >>> Order(joe, big_cart, LargeOrderPromo())  # <8>
+    >>> Order(joe, long_cart, LargeOrderPromo())  # <8>
     <Order total: 10.00 due: 9.30>
     >>> Order(joe, cart, LargeOrderPromo())
     <Order total: 42.00 due: 42.00>
@@ -29,44 +29,37 @@
 # tag::CLASSIC_STRATEGY[]
 
 from abc import ABC, abstractmethod
-import typing
+from collections.abc import Sequence
-from typing import Sequence, Optional
+from decimal import Decimal
+from typing import NamedTuple, Optional
 
 
-class Customer(typing.NamedTuple):
+class Customer(NamedTuple):
     name: str
     fidelity: int
 
 
-class LineItem:
+class LineItem(NamedTuple):
-    def __init__(self, product: str, quantity: int, price: float):
+    product: str
-        self.product = product
+    quantity: int
-        self.quantity = quantity
+    price: Decimal
-        self.price = price
 
-    def total(self):
+    def total(self) -> Decimal:
         return self.price * self.quantity
 
 
-class Order:  # the Context
+class Order(NamedTuple):  # the Context
-    def __init__(
+    customer: Customer
-        self,
+    cart: Sequence[LineItem]
-        customer: Customer,
+    promotion: Optional['Promotion'] = None
-        cart: Sequence[LineItem],
-        promotion: Optional['Promotion'] = None,
-    ):
-        self.customer = customer
-        self.cart = list(cart)
-        self.promotion = promotion
 
-    def total(self) -> float:
+    def total(self) -> Decimal:
-        if not hasattr(self, '__total'):
+        totals = (item.total() for item in self.cart)
-            self.__total = sum(item.total() for item in self.cart)
+        return sum(totals, start=Decimal(0))
-        return self.__total
 
-    def due(self) -> float:
+    def due(self) -> Decimal:
         if self.promotion is None:
-            discount = 0.0
+            discount = Decimal(0)
         else:
             discount = self.promotion.discount(self)
         return self.total() - discount
@@ -77,36 +70,37 @@ class Order:  # the Context
 
 class Promotion(ABC):  # the Strategy: an abstract base class
     @abstractmethod
-    def discount(self, order: Order) -> float:
+    def discount(self, order: Order) -> Decimal:
         """Return discount as a positive dollar amount"""
 
 
 class FidelityPromo(Promotion):  # first Concrete Strategy
     """5% discount for customers with 1000 or more fidelity points"""
 
-    def discount(self, order: Order) -> float:
+    def discount(self, order: Order) -> Decimal:
-        return order.total() * 0.05 if order.customer.fidelity >= 1000 else 0
+        rate = Decimal('0.05')
+        if order.customer.fidelity >= 1000:
+            return order.total() * rate
+        return Decimal(0)
 
 
 class BulkItemPromo(Promotion):  # second Concrete Strategy
     """10% discount for each LineItem with 20 or more units"""
 
-    def discount(self, order: Order) -> float:
+    def discount(self, order: Order) -> Decimal:
-        discount = 0
+        discount = Decimal(0)
         for item in order.cart:
             if item.quantity >= 20:
-                discount += item.total() * 0.1
+                discount += item.total() * Decimal('0.1')
         return discount
 
 
 class LargeOrderPromo(Promotion):  # third Concrete Strategy
     """7% discount for orders with 10 or more distinct items"""
 
-    def discount(self, order: Order) -> float:
+    def discount(self, order: Order) -> Decimal:
         distinct_items = {item.product for item in order.cart}
         if len(distinct_items) >= 10:
-            return order.total() * 0.07
+            return order.total() * Decimal('0.07')
-        return 0
+        return Decimal(0)
-
-
 # end::CLASSIC_STRATEGY[]

10-dp-1class-func/classic_strategy_test.py

@@ -1,4 +1,4 @@
-from typing import List
+from decimal import Decimal
 
 import pytest  # type: ignore
 
@@ -17,47 +17,49 @@ def customer_fidelity_1100() -> Customer:
 
 
 @pytest.fixture
-def cart_plain() -> List[LineItem]:
+def cart_plain() -> tuple[LineItem, ...]:
-    return [
+    return (
-        LineItem('banana', 4, 0.5),
+        LineItem('banana', 4, Decimal('0.5')),
-        LineItem('apple', 10, 1.5),
+        LineItem('apple', 10, Decimal('1.5')),
-        LineItem('watermelon', 5, 5.0),
+        LineItem('watermelon', 5, Decimal('5.0')),
-    ]
+    )
 
 
 def test_fidelity_promo_no_discount(customer_fidelity_0, cart_plain) -> None:
     order = Order(customer_fidelity_0, cart_plain, FidelityPromo())
-    assert order.total() == 42.0
+    assert order.total() == 42
-    assert order.due() == 42.0
+    assert order.due() == 42
 
 
 def test_fidelity_promo_with_discount(customer_fidelity_1100, cart_plain) -> None:
     order = Order(customer_fidelity_1100, cart_plain, FidelityPromo())
-    assert order.total() == 42.0
+    assert order.total() == 42
-    assert order.due() == 39.9
+    assert order.due() == Decimal('39.9')
 
 
 def test_bulk_item_promo_no_discount(customer_fidelity_0, cart_plain) -> None:
     order = Order(customer_fidelity_0, cart_plain, BulkItemPromo())
-    assert order.total() == 42.0
+    assert order.total() == 42
-    assert order.due() == 42.0
+    assert order.due() == 42
 
 
 def test_bulk_item_promo_with_discount(customer_fidelity_0) -> None:
-    cart = [LineItem('banana', 30, 0.5), LineItem('apple', 10, 1.5)]
+    cart = [LineItem('banana', 30, Decimal('0.5')),
+            LineItem('apple', 10, Decimal('1.5'))]
     order = Order(customer_fidelity_0, cart, BulkItemPromo())
-    assert order.total() == 30.0
+    assert order.total() == 30
-    assert order.due() == 28.5
+    assert order.due() == Decimal('28.5')
 
 
 def test_large_order_promo_no_discount(customer_fidelity_0, cart_plain) -> None:
     order = Order(customer_fidelity_0, cart_plain, LargeOrderPromo())
-    assert order.total() == 42.0
+    assert order.total() == 42
-    assert order.due() == 42.0
+    assert order.due() == 42
 
 
 def test_large_order_promo_with_discount(customer_fidelity_0) -> None:
-    cart = [LineItem(str(item_code), 1, 1.0) for item_code in range(10)]
+    cart = [LineItem(str(item_code), 1, Decimal(1))
+            for item_code in range(10)]
     order = Order(customer_fidelity_0, cart, LargeOrderPromo())
-    assert order.total() == 10.0
+    assert order.total() == 10
-    assert order.due() == 9.3
+    assert order.due() == Decimal('9.3')

10-dp-1class-func/monkeytype/classic_strategy.py

@@ -17,9 +17,9 @@
     ...                LineItem('apple', 10, 1.5)]
     >>> Order(joe, banana_cart, BulkItemPromo())  # <6>
     <Order total: 30.00 due: 28.50>
-    >>> long_order = [LineItem(str(item_code), 1, 1.0) # <7>
+    >>> long_cart = [LineItem(str(item_code), 1, 1.0) # <7>
     ...               for item_code in range(10)]
-    >>> Order(joe, long_order, LargeOrderPromo())  # <8>
+    >>> Order(joe, long_cart, LargeOrderPromo())  # <8>
     <Order total: 10.00 due: 9.30>
     >>> Order(joe, cart, LargeOrderPromo())
     <Order total: 42.00 due: 42.00>

10-dp-1class-func/promotions.py

@@ -1,20 +1,25 @@
-def fidelity_promo(order):
+from decimal import Decimal
+from strategy import Order
+
+def fidelity_promo(order: Order) -> Decimal:  # <3>
     """5% discount for customers with 1000 or more fidelity points"""
-    return order.total() * 0.05 if order.customer.fidelity >= 1000 else 0
+    if order.customer.fidelity >= 1000:
+        return order.total() * Decimal('0.05')
+    return Decimal(0)
 
 
-def bulk_item_promo(order):
+def bulk_item_promo(order: Order) -> Decimal:
     """10% discount for each LineItem with 20 or more units"""
-    discount = 0
+    discount = Decimal(0)
     for item in order.cart:
         if item.quantity >= 20:
-            discount += item.total() * 0.1
+            discount += item.total() * Decimal('0.1')
     return discount
 
 
-def large_order_promo(order):
+def large_order_promo(order: Order) -> Decimal:
     """7% discount for orders with 10 or more distinct items"""
     distinct_items = {item.product for item in order.cart}
     if len(distinct_items) >= 10:
-        return order.total() * 0.07
+        return order.total() * Decimal('0.07')
-    return 0
+    return Decimal(0)

10-dp-1class-func/pytypes/classic_strategy.py

@@ -17,9 +17,9 @@
     ...                LineItem('apple', 10, 1.5)]
     >>> Order(joe, banana_cart, BulkItemPromo())  # <6>
     <Order total: 30.00 due: 28.50>
-    >>> long_order = [LineItem(str(item_code), 1, 1.0) # <7>
+    >>> long_cart = [LineItem(str(item_code), 1, 1.0) # <7>
     ...               for item_code in range(10)]
-    >>> Order(joe, long_order, LargeOrderPromo())  # <8>
+    >>> Order(joe, long_cart, LargeOrderPromo())  # <8>
     <Order total: 10.00 due: 9.30>
     >>> Order(joe, cart, LargeOrderPromo())
     <Order total: 42.00 due: 42.00>

10-dp-1class-func/requirements.txt

@@ -1,13 +1,2 @@
-mypy==0.770
+mypy==0.910
-mypy-extensions==0.4.3
+pytest==6.2.4
-typed-ast==1.4.1
-typing-extensions==3.7.4.1
-attrs==19.3.0
-more-itertools==8.2.0
-packaging==20.3
-pluggy==0.13.1
-py==1.10.0
-pyparsing==2.4.6
-pytest==5.4.1
-six==1.14.0
-wcwidth==0.1.9

10-dp-1class-func/strategy.py

@@ -6,20 +6,20 @@
 
     >>> joe = Customer('John Doe', 0)  # <1>
     >>> ann = Customer('Ann Smith', 1100)
-    >>> cart = [LineItem('banana', 4, .5),
+    >>> cart = [LineItem('banana', 4, Decimal('.5')),
-    ...         LineItem('apple', 10, 1.5),
+    ...         LineItem('apple', 10, Decimal('1.5')),
-    ...         LineItem('watermelon', 5, 5.0)]
+    ...         LineItem('watermelon', 5, Decimal(5))]
     >>> Order(joe, cart, fidelity_promo)  # <2>
     <Order total: 42.00 due: 42.00>
     >>> Order(ann, cart, fidelity_promo)
     <Order total: 42.00 due: 39.90>
-    >>> banana_cart = [LineItem('banana', 30, .5),
+    >>> banana_cart = [LineItem('banana', 30, Decimal('.5')),
-    ...                LineItem('apple', 10, 1.5)]
+    ...                LineItem('apple', 10, Decimal('1.5'))]
     >>> Order(joe, banana_cart, bulk_item_promo)  # <3>
     <Order total: 30.00 due: 28.50>
-    >>> big_cart = [LineItem(str(item_code), 1, 1.0)
+    >>> long_cart = [LineItem(str(item_code), 1, Decimal(1))
     ...               for item_code in range(10)]
-    >>> Order(joe, big_cart, large_order_promo)
+    >>> Order(joe, long_cart, large_order_promo)
     <Order total: 10.00 due: 9.30>
     >>> Order(joe, cart, large_order_promo)
     <Order total: 42.00 due: 42.00>
@@ -28,75 +28,71 @@
 """
 # tag::STRATEGY[]
 
-import typing
+from collections.abc import Sequence
-from typing import Sequence, Optional, Callable
+from dataclasses import dataclass
+from decimal import Decimal
+from typing import Optional, Callable, NamedTuple
 
 
-class Customer(typing.NamedTuple):
+class Customer(NamedTuple):
     name: str
     fidelity: int
 
 
-class LineItem:
+class LineItem(NamedTuple):
-    def __init__(self, product: str, quantity: int, price: float):
+    product: str
-        self.product = product
+    quantity: int
-        self.quantity = quantity
+    price: Decimal
-        self.price = price
 
     def total(self):
         return self.price * self.quantity
 
-
+@dataclass(frozen=True)
 class Order:  # the Context
-    def __init__(
+    customer: Customer
-        self,
+    cart: Sequence[LineItem]
-        customer: Customer,
+    promotion: Optional[Callable[['Order'], Decimal]] = None  # <1>
-        cart: Sequence[LineItem],
-        promotion: Optional[Callable[['Order'], float]] = None,
-    ) -> None:
-        self.customer = customer
-        self.cart = list(cart)
-        self.promotion = promotion
 
-    def total(self) -> float:
+    def total(self) -> Decimal:
-        if not hasattr(self, '__total'):
+        totals = (item.total() for item in self.cart)
-            self.__total = sum(item.total() for item in self.cart)
+        return sum(totals, start=Decimal(0))
-        return self.__total
 
-    def due(self) -> float:
+    def due(self) -> Decimal:
         if self.promotion is None:
-            discount = 0.0
+            discount = Decimal(0)
         else:
-            discount = self.promotion(self)  # <1>
+            discount = self.promotion(self)  # <2>
         return self.total() - discount
 
     def __repr__(self):
         return f'<Order total: {self.total():.2f} due: {self.due():.2f}>'
 
 
-# <2>
+# <3>
 
 
-def fidelity_promo(order: Order) -> float:  # <3>
+def fidelity_promo(order: Order) -> Decimal:  # <4>
     """5% discount for customers with 1000 or more fidelity points"""
-    return order.total() * 0.05 if order.customer.fidelity >= 1000 else 0
+    if order.customer.fidelity >= 1000:
+        return order.total() * Decimal('0.05')
+    return Decimal(0)
 
 
-def bulk_item_promo(order: Order):
+def bulk_item_promo(order: Order) -> Decimal:
     """10% discount for each LineItem with 20 or more units"""
-    discount = 0
+    discount = Decimal(0)
     for item in order.cart:
         if item.quantity >= 20:
-            discount += item.total() * 0.1
+            discount += item.total() * Decimal('0.1')
     return discount
 
 
-def large_order_promo(order: Order):
+def large_order_promo(order: Order) -> Decimal:
     """7% discount for orders with 10 or more distinct items"""
     distinct_items = {item.product for item in order.cart}
     if len(distinct_items) >= 10:
-        return order.total() * 0.07
+        return order.total() * Decimal('0.07')
-    return 0
+    return Decimal(0)
 
 
 # end::STRATEGY[]

10-dp-1class-func/strategy_best.py

@@ -3,19 +3,20 @@
 # selecting best promotion from static list of functions
 
 """
+    >>> from strategy import Customer, LineItem
     >>> joe = Customer('John Doe', 0)
     >>> ann = Customer('Ann Smith', 1100)
-    >>> cart = [LineItem('banana', 4, .5),
+    >>> cart = [LineItem('banana', 4, Decimal('.5')),
-    ...         LineItem('apple', 10, 1.5),
+    ...         LineItem('apple', 10, Decimal('1.5')),
-    ...         LineItem('watermelon', 5, 5.0)]
+    ...         LineItem('watermelon', 5, Decimal(5))]
-    >>> banana_cart = [LineItem('banana', 30, .5),
+    >>> banana_cart = [LineItem('banana', 30, Decimal('.5')),
-    ...                LineItem('apple', 10, 1.5)]
+    ...                LineItem('apple', 10, Decimal('1.5'))]
-    >>> big_cart = [LineItem(str(item_code), 1, 1.0)
+    >>> long_cart = [LineItem(str(item_code), 1, Decimal(1))
     ...               for item_code in range(10)]
 
 # tag::STRATEGY_BEST_TESTS[]
 
-    >>> Order(joe, big_cart, best_promo)  # <1>
+    >>> Order(joe, long_cart, best_promo)  # <1>
     <Order total: 10.00 due: 9.30>
     >>> Order(joe, banana_cart, best_promo)  # <2>
     <Order total: 30.00 due: 28.50>
@@ -25,7 +26,9 @@
 # end::STRATEGY_BEST_TESTS[]
 """
 
-from strategy import Customer, LineItem, Order
+from decimal import Decimal
+
+from strategy import Order
 from strategy import fidelity_promo, bulk_item_promo, large_order_promo
 
 # tag::STRATEGY_BEST[]
@@ -33,9 +36,8 @@ from strategy import fidelity_promo, bulk_item_promo, large_order_promo
 promos = [fidelity_promo, bulk_item_promo, large_order_promo]  # <1>
 
 
-def best_promo(order) -> float:  # <2>
+def best_promo(order: Order) -> Decimal:  # <2>
-    """Select best discount available
+    """Compute the best discount available"""
-    """
     return max(promo(order) for promo in promos)  # <3>
 
 

10-dp-1class-func/strategy_best2.py

@@ -3,29 +3,31 @@
 # selecting best promotion from current module globals
 
 """
+    >>> from decimal import Decimal
+    >>> from strategy import Customer, LineItem, Order
     >>> joe = Customer('John Doe', 0)
     >>> ann = Customer('Ann Smith', 1100)
-    >>> cart = [LineItem('banana', 4, .5),
+    >>> cart = [LineItem('banana', 4, Decimal('.5')),
-    ...         LineItem('apple', 10, 1.5),
+    ...         LineItem('apple', 10, Decimal('1.5')),
-    ...         LineItem('watermelon', 5, 5.0)]
+    ...         LineItem('watermelon', 5, Decimal(5))]
     >>> Order(joe, cart, fidelity_promo)
     <Order total: 42.00 due: 42.00>
     >>> Order(ann, cart, fidelity_promo)
     <Order total: 42.00 due: 39.90>
-    >>> banana_cart = [LineItem('banana', 30, .5),
+    >>> banana_cart = [LineItem('banana', 30, Decimal('.5')),
-    ...                LineItem('apple', 10, 1.5)]
+    ...                LineItem('apple', 10, Decimal('1.5'))]
     >>> Order(joe, banana_cart, bulk_item_promo)
     <Order total: 30.00 due: 28.50>
-    >>> long_order = [LineItem(str(item_code), 1, 1.0)
+    >>> long_cart = [LineItem(str(item_code), 1, Decimal(1))
     ...               for item_code in range(10)]
-    >>> Order(joe, long_order, large_order_promo)
+    >>> Order(joe, long_cart, large_order_promo)
     <Order total: 10.00 due: 9.30>
     >>> Order(joe, cart, large_order_promo)
     <Order total: 42.00 due: 42.00>
 
 # tag::STRATEGY_BEST_TESTS[]
 
-    >>> Order(joe, long_order, best_promo)
+    >>> Order(joe, long_cart, best_promo)
     <Order total: 10.00 due: 9.30>
     >>> Order(joe, banana_cart, best_promo)
     <Order total: 30.00 due: 28.50>
@@ -35,78 +37,21 @@
 # end::STRATEGY_BEST_TESTS[]
 """
 
-from collections import namedtuple
-
-Customer = namedtuple('Customer', 'name fidelity')
-
-
-class LineItem:
-    def __init__(self, product, quantity, price):
-        self.product = product
-        self.quantity = quantity
-        self.price = price
-
-    def total(self):
-        return self.price * self.quantity
-
-
-class Order:  # the Context
-    def __init__(self, customer, cart, promotion=None):
-        self.customer = customer
-        self.cart = list(cart)
-        self.promotion = promotion
-
-    def total(self):
-        if not hasattr(self, '__total'):
-            self.__total = sum(item.total() for item in self.cart)
-        return self.__total
-
-    def due(self):
-        if self.promotion is None:
-            discount = 0
-        else:
-            discount = self.promotion(self)
-        return self.total() - discount
-
-    def __repr__(self):
-        return f'<Order total: {self.total():.2f} due: {self.due():.2f}>'
-
-
-def fidelity_promo(order):
-    """5% discount for customers with 1000 or more fidelity points"""
-    return order.total() * 0.05 if order.customer.fidelity >= 1000 else 0
-
-
-def bulk_item_promo(order):
-    """10% discount for each LineItem with 20 or more units"""
-    discount = 0
-    for item in order.cart:
-        if item.quantity >= 20:
-            discount += item.total() * 0.1
-    return discount
-
-
-def large_order_promo(order):
-    """7% discount for orders with 10 or more distinct items"""
-    distinct_items = {item.product for item in order.cart}
-    if len(distinct_items) >= 10:
-        return order.total() * 0.07
-    return 0
-
-
 # tag::STRATEGY_BEST2[]
+from decimal import Decimal
+from strategy import Order
+from strategy import (
+    fidelity_promo, bulk_item_promo, large_order_promo  # <1>
+)
 
-promos = [
+promos = [promo for name, promo in globals().items()  # <2>
-    globals()[name]
+                if name.endswith('_promo') and        # <3>
-    for name in globals()  # <1>
+                   name != 'best_promo'               # <4>
-    if name.endswith('_promo') and name != 'best_promo'  # <2>
+]
-]  # <3>
 
 
-def best_promo(order):
+def best_promo(order: Order) -> Decimal:              # <5>
-    """Select best discount available
+    """Compute the best discount available"""
-    """
+    return max(promo(order) for promo in promos)
-    return max(promo(order) for promo in promos)  # <4>
-
 
 # end::STRATEGY_BEST2[]

10-dp-1class-func/strategy_best3.py

@@ -3,30 +3,32 @@
 # selecting best promotion from imported module
 
 """
+    >>> from decimal import Decimal
+    >>> from strategy import Customer, LineItem, Order
     >>> from promotions import *
     >>> joe = Customer('John Doe', 0)
     >>> ann = Customer('Ann Smith', 1100)
-    >>> cart = [LineItem('banana', 4, .5),
+    >>> cart = [LineItem('banana', 4, Decimal('.5')),
-    ...         LineItem('apple', 10, 1.5),
+    ...         LineItem('apple', 10, Decimal('1.5')),
-    ...         LineItem('watermelon', 5, 5.0)]
+    ...         LineItem('watermelon', 5, Decimal(5))]
     >>> Order(joe, cart, fidelity_promo)
     <Order total: 42.00 due: 42.00>
     >>> Order(ann, cart, fidelity_promo)
     <Order total: 42.00 due: 39.90>
-    >>> banana_cart = [LineItem('banana', 30, .5),
+    >>> banana_cart = [LineItem('banana', 30, Decimal('.5')),
-    ...                LineItem('apple', 10, 1.5)]
+    ...                LineItem('apple', 10, Decimal('1.5'))]
     >>> Order(joe, banana_cart, bulk_item_promo)
     <Order total: 30.00 due: 28.50>
-    >>> long_order = [LineItem(str(item_code), 1, 1.0)
+    >>> long_cart = [LineItem(str(item_code), 1, Decimal(1))
     ...               for item_code in range(10)]
-    >>> Order(joe, long_order, large_order_promo)
+    >>> Order(joe, long_cart, large_order_promo)
     <Order total: 10.00 due: 9.30>
     >>> Order(joe, cart, large_order_promo)
     <Order total: 42.00 due: 42.00>
 
 # tag::STRATEGY_BEST_TESTS[]
 
-    >>> Order(joe, long_order, best_promo)
+    >>> Order(joe, long_cart, best_promo)
     <Order total: 10.00 due: 9.30>
     >>> Order(joe, banana_cart, best_promo)
     <Order total: 30.00 due: 28.50>
@@ -36,55 +38,20 @@
 # end::STRATEGY_BEST_TESTS[]
 """
 
-from collections import namedtuple
-import inspect
-
-import promotions
-
-Customer = namedtuple('Customer', 'name fidelity')
-
-
-class LineItem:
-    def __init__(self, product, quantity, price):
-        self.product = product
-        self.quantity = quantity
-        self.price = price
-
-    def total(self):
-        return self.price * self.quantity
-
-
-class Order:  # the Context
-    def __init__(self, customer, cart, promotion=None):
-        self.customer = customer
-        self.cart = list(cart)
-        self.promotion = promotion
-
-    def total(self):
-        if not hasattr(self, '__total'):
-            self.__total = sum(item.total() for item in self.cart)
-        return self.__total
-
-    def due(self):
-        if self.promotion is None:
-            discount = 0
-        else:
-            discount = self.promotion(self)
-        return self.total() - discount
-
-    def __repr__(self):
-        return f'<Order total: {self.total():.2f} due: {self.due():.2f}>'
-
-
 # tag::STRATEGY_BEST3[]
 
-promos = [func for name, func in inspect.getmembers(promotions, inspect.isfunction)]
+from decimal import Decimal
+import inspect
+
+from strategy import Order
+import promotions
 
 
-def best_promo(order):
+promos = [func for _, func in inspect.getmembers(promotions, inspect.isfunction)]
-    """Select best discount available
+
-    """
+
+def best_promo(order: Order) -> Decimal:
+    """Compute the best discount available"""
     return max(promo(order) for promo in promos)
 
-
 # end::STRATEGY_BEST3[]

10-dp-1class-func/strategy_best4.py

@@ -4,29 +4,32 @@
 # registered by a decorator
 
 """
+    >>> from decimal import Decimal
+    >>> from strategy import Customer, LineItem, Order
+    >>> from promotions import *
     >>> joe = Customer('John Doe', 0)
     >>> ann = Customer('Ann Smith', 1100)
-    >>> cart = [LineItem('banana', 4, .5),
+    >>> cart = [LineItem('banana', 4, Decimal('.5')),
-    ...         LineItem('apple', 10, 1.5),
+    ...         LineItem('apple', 10, Decimal('1.5')),
-    ...         LineItem('watermelon', 5, 5.0)]
+    ...         LineItem('watermelon', 5, Decimal(5))]
-    >>> Order(joe, cart, fidelity)
+    >>> Order(joe, cart, fidelity_promo)
     <Order total: 42.00 due: 42.00>
-    >>> Order(ann, cart, fidelity)
+    >>> Order(ann, cart, fidelity_promo)
     <Order total: 42.00 due: 39.90>
-    >>> banana_cart = [LineItem('banana', 30, .5),
+    >>> banana_cart = [LineItem('banana', 30, Decimal('.5')),
-    ...                LineItem('apple', 10, 1.5)]
+    ...                LineItem('apple', 10, Decimal('1.5'))]
-    >>> Order(joe, banana_cart, bulk_item)
+    >>> Order(joe, banana_cart, bulk_item_promo)
     <Order total: 30.00 due: 28.50>
-    >>> long_order = [LineItem(str(item_code), 1, 1.0)
+    >>> long_cart = [LineItem(str(item_code), 1, Decimal(1))
     ...               for item_code in range(10)]
-    >>> Order(joe, long_order, large_order)
+    >>> Order(joe, long_cart, large_order_promo)
     <Order total: 10.00 due: 9.30>
-    >>> Order(joe, cart, large_order)
+    >>> Order(joe, cart, large_order_promo)
     <Order total: 42.00 due: 42.00>
 
 # tag::STRATEGY_BEST_TESTS[]
 
-    >>> Order(joe, long_order, best_promo)
+    >>> Order(joe, long_cart, best_promo)
     <Order total: 10.00 due: 9.30>
     >>> Order(joe, banana_cart, best_promo)
     <Order total: 30.00 due: 28.50>
@@ -36,47 +39,16 @@
 # end::STRATEGY_BEST_TESTS[]
 """
 
-from collections import namedtuple
+from decimal import Decimal
-from typing import Callable, List
+from typing import Callable
-
-Customer = namedtuple('Customer', 'name fidelity')
-
-
-class LineItem:
-    def __init__(self, product, quantity, price):
-        self.product = product
-        self.quantity = quantity
-        self.price = price
-
-    def total(self):
-        return self.price * self.quantity
-
-
-class Order:  # the Context
-    def __init__(self, customer, cart, promotion=None):
-        self.customer = customer
-        self.cart = list(cart)
-        self.promotion = promotion
-
-    def total(self):
-        if not hasattr(self, '__total'):
-            self.__total = sum(item.total() for item in self.cart)
-        return self.__total
-
-    def due(self):
-        if self.promotion is None:
-            discount = 0
-        else:
-            discount = self.promotion(self)
-        return self.total() - discount
-
-    def __repr__(self):
-        return f'<Order total: {self.total():.2f} due: {self.due():.2f}>'
 
+from strategy import Order
 
 # tag::STRATEGY_BEST4[]
 
-Promotion = Callable[[Order], float]  # <2>
+Promotion = Callable[[Order], Decimal]
+
+promos: list[Promotion] = []  # <1>
 
 
 def promotion(promo: Promotion) -> Promotion:  # <2>
@@ -84,38 +56,35 @@ def promotion(promo: Promotion) -> Promotion:  # <2>
     return promo
 
 
-promos: List[Promotion] = []  # <1>
+def best_promo(order: Order) -> Decimal:
+    """Compute the best discount available"""
+    return max(promo(order) for promo in promos)  # <3>
 
 
-@promotion  # <3>
+@promotion  # <4>
-def fidelity(order: Order) -> float:
+def fidelity(order: Order) -> Decimal:
     """5% discount for customers with 1000 or more fidelity points"""
-    return order.total() * 0.05 if order.customer.fidelity >= 1000 else 0
+    if order.customer.fidelity >= 1000:
+        return order.total() * Decimal('0.05')
+    return Decimal(0)
 
 
 @promotion
-def bulk_item(order: Order) -> float:
+def bulk_item(order: Order) -> Decimal:
     """10% discount for each LineItem with 20 or more units"""
-    discount = 0
+    discount = Decimal(0)
     for item in order.cart:
         if item.quantity >= 20:
-            discount += item.total() * 0.1
+            discount += item.total() * Decimal('0.1')
     return discount
 
 
 @promotion
-def large_order(order: Order) -> float:
+def large_order(order: Order) -> Decimal:
     """7% discount for orders with 10 or more distinct items"""
     distinct_items = {item.product for item in order.cart}
     if len(distinct_items) >= 10:
-        return order.total() * 0.07
+        return order.total() * Decimal('0.07')
-    return 0
+    return Decimal(0)
-
-
-def best_promo(order: Order) -> float:  # <4>
-    """Select best discount available
-    """
-    return max(promo(order) for promo in promos)
-
 
 # end::STRATEGY_BEST4[]

10-dp-1class-func/strategy_param.py

@@ -15,9 +15,9 @@
     ...                LineItem('apple', 10, 1.5)]
     >>> Order(joe, banana_cart, bulk_item_promo(10))
     <Order total: 30.00 due: 28.50>
-    >>> big_cart = [LineItem(str(item_code), 1, 1.0)
+    >>> long_cart = [LineItem(str(item_code), 1, 1.0)
     ...               for item_code in range(10)]
-    >>> Order(joe, big_cart, LargeOrderPromo(7))
+    >>> Order(joe, long_cart, LargeOrderPromo(7))
     <Order total: 10.00 due: 9.30>
     >>> Order(joe, cart, LargeOrderPromo(7))
     <Order total: 42.00 due: 42.00>

10-dp-1class-func/strategy_param_test.py

@@ -47,7 +47,7 @@ def test_large_order_promo_with_discount(customer_fidelity_0) -> None:
     assert order.due() == 9.3
 
 
-def test_general_discount(customer_fidelity_0, cart_plain) -> None:
+def test_general_discount(customer_fidelity_1100, cart_plain) -> None:
     general_promo: Promotion = functools.partial(general_discount, 5)
     order = Order(customer_fidelity_1100, cart_plain, general_promo)
     assert order.total() == 42.0

10-dp-1class-func/strategy_test.py

@@ -1,4 +1,4 @@
-from typing import List
+from decimal import Decimal
 
 import pytest  # type: ignore
 
@@ -17,47 +17,50 @@ def customer_fidelity_1100() -> Customer:
 
 
 @pytest.fixture
-def cart_plain() -> List[LineItem]:
+def cart_plain() -> tuple[LineItem, ...]:
-    return [
+    return (
-        LineItem('banana', 4, 0.5),
+        LineItem('banana', 4, Decimal('0.5')),
-        LineItem('apple', 10, 1.5),
+        LineItem('apple', 10, Decimal('1.5')),
-        LineItem('watermelon', 5, 5.0),
+        LineItem('watermelon', 5, Decimal('5.0')),
-    ]
+    )
 
 
 def test_fidelity_promo_no_discount(customer_fidelity_0, cart_plain) -> None:
     order = Order(customer_fidelity_0, cart_plain, fidelity_promo)
-    assert order.total() == 42.0
+    assert order.total() == 42
-    assert order.due() == 42.0
+    assert order.due() == 42
 
 
 def test_fidelity_promo_with_discount(customer_fidelity_1100, cart_plain) -> None:
     order = Order(customer_fidelity_1100, cart_plain, fidelity_promo)
-    assert order.total() == 42.0
+    assert order.total() == 42
-    assert order.due() == 39.9
+    assert order.due() == Decimal('39.9')
 
 
 def test_bulk_item_promo_no_discount(customer_fidelity_0, cart_plain) -> None:
     order = Order(customer_fidelity_0, cart_plain, bulk_item_promo)
-    assert order.total() == 42.0
+    assert order.total() == 42
-    assert order.due() == 42.0
+    assert order.due() == 42
 
 
 def test_bulk_item_promo_with_discount(customer_fidelity_0) -> None:
-    cart = [LineItem('banana', 30, 0.5), LineItem('apple', 10, 1.5)]
+    cart = [LineItem('banana', 30, Decimal('0.5')),
+            LineItem('apple', 10, Decimal('1.5'))]
     order = Order(customer_fidelity_0, cart, bulk_item_promo)
-    assert order.total() == 30.0
+    assert order.total() == 30
-    assert order.due() == 28.5
+    assert order.due() == Decimal('28.5')
 
 
 def test_large_order_promo_no_discount(customer_fidelity_0, cart_plain) -> None:
     order = Order(customer_fidelity_0, cart_plain, large_order_promo)
-    assert order.total() == 42.0
+    assert order.total() == 42
-    assert order.due() == 42.0
+    assert order.due() == 42
 
 
 def test_large_order_promo_with_discount(customer_fidelity_0) -> None:
-    cart = [LineItem(str(item_code), 1, 1.0) for item_code in range(10)]
+
+    cart = [LineItem(str(item_code), 1, Decimal(1))
+            for item_code in range(10)]
     order = Order(customer_fidelity_0, cart, large_order_promo)
-    assert order.total() == 10.0
+    assert order.total() == 10
-    assert order.due() == 9.3
+    assert order.due() == Decimal('9.3')

10-dp-1class-func/untyped/classic_strategy.py

@@ -17,9 +17,9 @@
     ...                LineItem('apple', 10, 1.5)]
     >>> Order(joe, banana_cart, BulkItemPromo())  # <6>
     <Order total: 30.00 due: 28.50>
-    >>> long_order = [LineItem(str(item_code), 1, 1.0) # <7>
+    >>> long_cart = [LineItem(str(item_code), 1, 1.0) # <7>
     ...               for item_code in range(10)]
-    >>> Order(joe, long_order, LargeOrderPromo())  # <8>
+    >>> Order(joe, long_cart, LargeOrderPromo())  # <8>
     <Order total: 10.00 due: 9.30>
     >>> Order(joe, cart, LargeOrderPromo())
     <Order total: 42.00 due: 42.00>

10-dp-1class-func/untyped/strategy.py

@@ -17,9 +17,9 @@
     ...                LineItem('apple', 10, 1.5)]
     >>> Order(joe, banana_cart, bulk_item_promo)  # <3>
     <Order total: 30.00 due: 28.50>
-    >>> long_order = [LineItem(str(item_code), 1, 1.0)
+    >>> long_cart = [LineItem(str(item_code), 1, 1.0)
     ...               for item_code in range(10)]
-    >>> Order(joe, long_order, large_order_promo)
+    >>> Order(joe, long_cart, large_order_promo)
     <Order total: 10.00 due: 9.30>
     >>> Order(joe, cart, large_order_promo)
     <Order total: 42.00 due: 42.00>

10-dp-1class-func/untyped/strategy_best.py

@@ -16,16 +16,16 @@
     ...                LineItem('apple', 10, 1.5)]
     >>> Order(joe, banana_cart, bulk_item_promo)
     <Order total: 30.00 due: 28.50>
-    >>> long_order = [LineItem(str(item_code), 1, 1.0)
+    >>> long_cart = [LineItem(str(item_code), 1, 1.0)
     ...               for item_code in range(10)]
-    >>> Order(joe, long_order, large_order_promo)
+    >>> Order(joe, long_cart, large_order_promo)
     <Order total: 10.00 due: 9.30>
     >>> Order(joe, cart, large_order_promo)
     <Order total: 42.00 due: 42.00>
 
 # tag::STRATEGY_BEST_TESTS[]
 
-    >>> Order(joe, long_order, best_promo)  # <1>
+    >>> Order(joe, long_cart, best_promo)  # <1>
     <Order total: 10.00 due: 9.30>
     >>> Order(joe, banana_cart, best_promo)  # <2>
     <Order total: 30.00 due: 28.50>

10-dp-1class-func/untyped/strategy_best2.py

@@ -16,16 +16,16 @@
     ...                LineItem('apple', 10, 1.5)]
     >>> Order(joe, banana_cart, bulk_item_promo)
     <Order total: 30.00 due: 28.50>
-    >>> long_order = [LineItem(str(item_code), 1, 1.0)
+    >>> long_cart = [LineItem(str(item_code), 1, 1.0)
     ...               for item_code in range(10)]
-    >>> Order(joe, long_order, large_order_promo)
+    >>> Order(joe, long_cart, large_order_promo)
     <Order total: 10.00 due: 9.30>
     >>> Order(joe, cart, large_order_promo)
     <Order total: 42.00 due: 42.00>
 
 # tag::STRATEGY_BEST_TESTS[]
 
-    >>> Order(joe, long_order, best_promo)
+    >>> Order(joe, long_cart, best_promo)
     <Order total: 10.00 due: 9.30>
     >>> Order(joe, banana_cart, best_promo)
     <Order total: 30.00 due: 28.50>

10-dp-1class-func/untyped/strategy_best3.py

@@ -17,16 +17,16 @@
     ...                LineItem('apple', 10, 1.5)]
     >>> Order(joe, banana_cart, bulk_item_promo)
     <Order total: 30.00 due: 28.50>
-    >>> long_order = [LineItem(str(item_code), 1, 1.0)
+    >>> long_cart = [LineItem(str(item_code), 1, 1.0)
     ...               for item_code in range(10)]
-    >>> Order(joe, long_order, large_order_promo)
+    >>> Order(joe, long_cart, large_order_promo)
     <Order total: 10.00 due: 9.30>
     >>> Order(joe, cart, large_order_promo)
     <Order total: 42.00 due: 42.00>
 
 # tag::STRATEGY_BEST_TESTS[]
 
-    >>> Order(joe, long_order, best_promo)
+    >>> Order(joe, long_cart, best_promo)
     <Order total: 10.00 due: 9.30>
     >>> Order(joe, banana_cart, best_promo)
     <Order total: 30.00 due: 28.50>

10-dp-1class-func/untyped/strategy_best4.py

@@ -17,16 +17,16 @@
     ...                LineItem('apple', 10, 1.5)]
     >>> Order(joe, banana_cart, bulk_item)
     <Order total: 30.00 due: 28.50>
-    >>> long_order = [LineItem(str(item_code), 1, 1.0)
+    >>> long_cart = [LineItem(str(item_code), 1, 1.0)
     ...               for item_code in range(10)]
-    >>> Order(joe, long_order, large_order)
+    >>> Order(joe, long_cart, large_order)
     <Order total: 10.00 due: 9.30>
     >>> Order(joe, cart, large_order)
     <Order total: 42.00 due: 42.00>
 
 # tag::STRATEGY_BEST_TESTS[]
 
-    >>> Order(joe, long_order, best_promo)
+    >>> Order(joe, long_cart, best_promo)
     <Order total: 10.00 due: 9.30>
     >>> Order(joe, banana_cart, best_promo)
     <Order total: 30.00 due: 28.50>

10-dp-1class-func/untyped/strategy_param.py

@@ -15,9 +15,9 @@
     ...                LineItem('apple', 10, 1.5)]
     >>> Order(joe, banana_cart, bulk_item_promo(10))
     <Order total: 30.00 due: 28.50>
-    >>> long_order = [LineItem(str(item_code), 1, 1.0)
+    >>> long_cart = [LineItem(str(item_code), 1, 1.0)
     ...               for item_code in range(10)]
-    >>> Order(joe, long_order, large_order_promo(7))
+    >>> Order(joe, long_cart, large_order_promo(7))
     <Order total: 10.00 due: 9.30>
     >>> Order(joe, cart, large_order_promo(7))
     <Order total: 42.00 due: 42.00>

10-dp-1class-func/untyped/strategy_param2.py

@@ -15,9 +15,9 @@
     ...                LineItem('apple', 10, 1.5)]
     >>> Order(joe, banana_cart, BulkItemPromo(10))
     <Order total: 30.00 due: 28.50>
-    >>> long_order = [LineItem(str(item_code), 1, 1.0)
+    >>> long_cart = [LineItem(str(item_code), 1, 1.0)
     ...               for item_code in range(10)]
-    >>> Order(joe, long_order, LargeOrderPromo(7))
+    >>> Order(joe, long_cart, LargeOrderPromo(7))
     <Order total: 10.00 due: 9.30>
     >>> Order(joe, cart, LargeOrderPromo(7))
     <Order total: 42.00 due: 42.00>

11-pythonic-obj/mem_test.py

@@ -4,20 +4,25 @@ import resource
 
 NUM_VECTORS = 10**7
 
+module = None
 if len(sys.argv) == 2:
     module_name = sys.argv[1].replace('.py', '')
     module = importlib.import_module(module_name)
 else:
     print(f'Usage: {sys.argv[0]} <vector-module-to-test>')
-    sys.exit(2)  # command line usage error
 
-fmt = 'Selected Vector2d type: {.__name__}.{.__name__}'
+if module is None:
-print(fmt.format(module, module.Vector2d))
+    print('Running test with built-in `complex`')
+    cls = complex
+else:
+    fmt = 'Selected Vector2d type: {.__name__}.{.__name__}'
+    print(fmt.format(module, module.Vector2d))
+    cls = module.Vector2d
 
 mem_init = resource.getrusage(resource.RUSAGE_SELF).ru_maxrss
-print(f'Creating {NUM_VECTORS:,} Vector2d instances')
+print(f'Creating {NUM_VECTORS:,} {cls.__qualname__!r} instances')
 
-vectors = [module.Vector2d(3.0, 4.0) for i in range(NUM_VECTORS)]
+vectors = [cls(3.0, 4.0) for i in range(NUM_VECTORS)]
 
 mem_final = resource.getrusage(resource.RUSAGE_SELF).ru_maxrss
 print(f'Initial RAM usage: {mem_init:14,}')

11-pythonic-obj/patterns.py

@@ -0,0 +1,53 @@
+from vector2d_v3 import Vector2d
+
+# tag::KEYWORD_PATTERNS[]
+def keyword_pattern_demo(v: Vector2d) -> None:
+    match v:
+        case Vector2d(x=0, y=0):
+            print(f'{v!r} is null')
+        case Vector2d(x=0):
+            print(f'{v!r} is vertical')
+        case Vector2d(y=0):
+            print(f'{v!r} is horizontal')
+        case Vector2d(x=x, y=y) if x==y:
+            print(f'{v!r} is diagonal')
+        case _:
+            print(f'{v!r} is awesome')
+# end::KEYWORD_PATTERNS[]
+
+# tag::POSITIONAL_PATTERNS[]
+def positional_pattern_demo(v: Vector2d) -> None:
+    match v:
+        case Vector2d(0, 0):
+            print(f'{v!r} is null')
+        case Vector2d(0):
+            print(f'{v!r} is vertical')
+        case Vector2d(_, 0):
+            print(f'{v!r} is horizontal')
+        case Vector2d(x, y) if x==y:
+            print(f'{v!r} is diagonal')
+        case _:
+            print(f'{v!r} is awesome')
+# end::POSITIONAL_PATTERNS[]
+
+
+def main():
+    vectors = (
+        Vector2d(1, 1),
+        Vector2d(0, 1),
+        Vector2d(1, 0),
+        Vector2d(1, 2),
+        Vector2d(0, 0),
+    )
+    print('KEYWORD PATTERNS:')
+    for vector in vectors:
+        keyword_pattern_demo(vector)
+
+    print('POSITIONAL PATTERNS:')
+    for vector in vectors:
+        positional_pattern_demo(vector)
+
+
+
+if __name__ == '__main__':
+    main()

11-pythonic-obj/slots.rst

@@ -0,0 +1,52 @@
+# tag::PIXEL[]
+>>> class Pixel:
+...     __slots__ = ('x', 'y')  # <1>
+...
+>>> p = Pixel()  # <2>
+>>> p.__dict__  # <3>
+Traceback (most recent call last):
+  ...
+AttributeError: 'Pixel' object has no attribute '__dict__'
+>>> p.x = 10  # <4>
+>>> p.y = 20
+>>> p.color = 'red'  # <5>
+Traceback (most recent call last):
+  ...
+AttributeError: 'Pixel' object has no attribute 'color'
+
+# end::PIXEL[]
+
+# tag::OPEN_PIXEL[]
+>>> class OpenPixel(Pixel):  # <1>
+...     pass
+...
+>>> op = OpenPixel()
+>>> op.__dict__  # <2>
+{}
+>>> op.x = 8  # <3>
+>>> op.__dict__  # <4>
+{}
+>>> op.x  # <5>
+8
+>>> op.color = 'green'  # <6>
+>>> op.__dict__  # <7>
+{'color': 'green'}
+
+# end::OPEN_PIXEL[]
+
+# tag::COLOR_PIXEL[]
+>>> class ColorPixel(Pixel):
+...    __slots__ = ('color',)  # <1>
+>>> cp = ColorPixel()
+>>> cp.__dict__  # <2>
+Traceback (most recent call last):
+  ...
+AttributeError: 'ColorPixel' object has no attribute '__dict__'
+>>> cp.x = 2
+>>> cp.color = 'blue'  # <3>
+>>> cp.flavor = 'banana'
+Traceback (most recent call last):
+  ...
+AttributeError: 'ColorPixel' object has no attribute 'flavor'
+
+# end::COLOR_PIXEL[]

11-pythonic-obj/vector2d_v3.py

@@ -72,7 +72,7 @@ Tests of `x` and `y` read-only properties:
     >>> v1.x = 123
     Traceback (most recent call last):
       ...
-    AttributeError: can't set attribute
+    AttributeError: can't set attribute 'x'
 
 
 Tests of hashing:
@@ -90,6 +90,8 @@ from array import array
 import math
 
 class Vector2d:
+    __match_args__ = ('x', 'y')
+
     typecode = 'd'
 
     def __init__(self, x, y):

11-pythonic-obj/vector2d_v3_prophash.py

@@ -72,7 +72,7 @@ Tests of `x` and `y` read-only properties:
     >>> v1.x = 123
     Traceback (most recent call last):
       ...
-    AttributeError: can't set attribute
+    AttributeError: can't set attribute 'x'
 
 # end::VECTOR2D_V3_HASH_DEMO[]
 
@@ -112,7 +112,7 @@ class Vector2d:
     def __iter__(self):
         return (i for i in (self.x, self.y))  # <6>
 
-    # remaining methods follow (omitted in book listing)
+    # remaining methods: same as previous Vector2d
 # end::VECTOR2D_V3_PROP[]
 
     def __repr__(self):

11-pythonic-obj/vector2d_v3_slots.py

@@ -72,7 +72,7 @@ Tests of `x` and `y` read-only properties:
     >>> v1.x = 123
     Traceback (most recent call last):
       ...
-    AttributeError: can't set attribute
+    AttributeError: can't set attribute 'x'
 
 Tests of hashing:
 
@@ -90,11 +90,10 @@ import math
 
 # tag::VECTOR2D_V3_SLOTS[]
 class Vector2d:
-    __slots__ = ('__x', '__y')
+    __match_args__ = ('x', 'y')  # <1>
+    __slots__ = ('__x', '__y')  # <2>
 
     typecode = 'd'
-
-    # methods follow (omitted in book listing)
 # end::VECTOR2D_V3_SLOTS[]
 
     def __init__(self, x, y):

12-seq-hacking/vector_v3.py

@@ -199,15 +199,17 @@ class Vector:
         return self._components[index]
 
 # tag::VECTOR_V3_GETATTR[]
-    shortcut_names = 'xyzt'
+    __match_args__ = ('x', 'y', 'z', 't')  # <1>
 
     def __getattr__(self, name):
-        cls = type(self)  # <1>
+        cls = type(self)  # <2>
-        if len(name) == 1:  # <2>
+        try:
-            pos = cls.shortcut_names.find(name)  # <3>
+            pos = cls.__match_args__.index(name)  # <3>
-            if 0 <= pos < len(self._components):  # <4>
+        except ValueError:  # <4>
-                return self._components[pos]
+            pos = -1
-        msg = f'{cls.__name__!r} object has no attribute {name!r}'  # <5>
+        if 0 <= pos < len(self._components):  # <5>
+            return self._components[pos]
+        msg = f'{cls.__name__!r} object has no attribute {name!r}'  # <6>
         raise AttributeError(msg)
 # end::VECTOR_V3_GETATTR[]
 
@@ -215,8 +217,8 @@ class Vector:
     def __setattr__(self, name, value):
         cls = type(self)
         if len(name) == 1:  # <1>
-            if name in cls.shortcut_names:  # <2>
+            if name in cls.__match_args__:  # <2>
-                error = 'read-only attribute {attr_name!r}'
+                error = 'readonly attribute {attr_name!r}'
             elif name.islower():  # <3>
                 error = "can't set attributes 'a' to 'z' in {cls_name!r}"
             else:

12-seq-hacking/vector_v4.py

@@ -199,14 +199,16 @@ class Vector:
         index = operator.index(key)
         return self._components[index]
 
-    shortcut_names = 'xyzt'
+    __match_args__ = ('x', 'y', 'z', 't')
 
     def __getattr__(self, name):
         cls = type(self)
-        if len(name) == 1:
+        try:
-            pos = cls.shortcut_names.find(name)
+            pos = cls.__match_args__.index(name)
-            if 0 <= pos < len(self._components):
+        except ValueError:
-                return self._components[pos]
+            pos = -1
+        if 0 <= pos < len(self._components):
+            return self._components[pos]
         msg = f'{cls.__name__!r} object has no attribute {name!r}'
         raise AttributeError(msg)
 

12-seq-hacking/vector_v5.py

@@ -242,14 +242,16 @@ class Vector:
         index = operator.index(key)
         return self._components[index]
 
-    shortcut_names = 'xyzt'
+    __match_args__ = ('x', 'y', 'z', 't')
 
     def __getattr__(self, name):
         cls = type(self)
-        if len(name) == 1:
+        try:
-            pos = cls.shortcut_names.find(name)
+            pos = cls.__match_args__.index(name)
-            if 0 <= pos < len(self._components):
+        except ValueError:
-                return self._components[pos]
+            pos = -1
+        if 0 <= pos < len(self._components):
+            return self._components[pos]
         msg = f'{cls.__name__!r} object has no attribute {name!r}'
         raise AttributeError(msg)
 

13-protocol-abc/frenchdeck2.py

@@ -1,8 +1,8 @@
-import collections
+from collections import namedtuple, abc
 
-Card = collections.namedtuple('Card', ['rank', 'suit'])
+Card = namedtuple('Card', ['rank', 'suit'])
 
-class FrenchDeck2(collections.MutableSequence):
+class FrenchDeck2(abc.MutableSequence):
     ranks = [str(n) for n in range(2, 11)] + list('JQKA')
     suits = 'spades diamonds clubs hearts'.split()
 

13-protocol-abc/typing/randompick_test.py

@@ -12,14 +12,14 @@ class SimplePicker:  # <2>
         return self._items.pop()
 
 def test_isinstance() -> None:  # <4>
-    popper = SimplePicker([1])
+    popper: RandomPicker = SimplePicker([1])  # <5>
-    assert isinstance(popper, RandomPicker)
+    assert isinstance(popper, RandomPicker)  # <6>
 
-def test_item_type() -> None:  # <5>
+def test_item_type() -> None:  # <7>
     items = [1, 2]
     popper = SimplePicker(items)
     item = popper.pick()
     assert item in items
     if TYPE_CHECKING:
-        reveal_type(item)  # <6>
+        reveal_type(item)  # <8>
     assert isinstance(item, int)

13-protocol-abc/typing/vector2d_v4.py

@@ -168,5 +168,5 @@ class Vector2d:
 
     @classmethod
     def fromcomplex(cls, datum):
-        return Vector2d(datum.real, datum.imag)  # <1>
+        return cls(datum.real, datum.imag)  # <1>
 # end::VECTOR2D_V4_COMPLEX[]

13-protocol-abc/typing/vector2d_v5.py

@@ -170,5 +170,5 @@ class Vector2d:
     @classmethod
     def fromcomplex(cls, datum: SupportsComplex) -> Vector2d:  # <3>
         c = complex(datum)  # <4>
-        return Vector2d(c.real, c.imag)
+        return cls(c.real, c.imag)
 # end::VECTOR2D_V5_COMPLEX[]

14-inheritance/uppermixin.py

@@ -1,10 +1,39 @@
-"""UpperDict uppercases all string keys.
+"""
+Short demos
+===========
 
-Test for initializer. `str` keys are uppercased::
+``UpperDict`` behaves like a case-insensitive mapping`::
+
+# tag::UPPERDICT_DEMO[]
+    >>> d = UpperDict([('a', 'letter A'), (2, 'digit two')])
+    >>> list(d.keys())
+    ['A', 2]
+    >>> d['b'] = 'letter B'
+    >>> 'b' in d
+    True
+    >>> d['a'], d.get('B')
+    ('letter A', 'letter B')
+    >>> list(d.keys())
+    ['A', 2, 'B']
+
+# end::UPPERDICT_DEMO[]
+
+And ``UpperCounter`` is also case-insensitive::
+
+# tag::UPPERCOUNTER_DEMO[]
+    >>> c = UpperCounter('BaNanA')
+    >>> c.most_common()
+    [('A', 3), ('N', 2), ('B', 1)]
+
+# end::UPPERCOUNTER_DEMO[]
+
+Detailed tests
+==============
+
+UpperDict uppercases all string keys.
 
     >>> d = UpperDict([('a', 'letter A'), ('B', 'letter B'), (2, 'digit two')])
-    >>> list(d.keys())
+
-    ['A', 'B', 2]
 
 Tests for item retrieval using `d[key]` notation::
 
@@ -82,14 +111,12 @@ Tests for count retrieval using `d[key]` notation::
 # tag::UPPERCASE_MIXIN[]
 import collections
 
-
 def _upper(key):  # <1>
     try:
         return key.upper()
     except AttributeError:
         return key
 
-
 class UpperCaseMixin:  # <2>
     def __setitem__(self, key, item):
         super().__setitem__(_upper(key), item)
@@ -108,8 +135,6 @@ class UpperCaseMixin:  # <2>
 class UpperDict(UpperCaseMixin, collections.UserDict):  # <1>
     pass
 
-
 class UpperCounter(UpperCaseMixin, collections.Counter):  # <2>
     """Specialized 'Counter' that uppercases string keys"""  # <3>
-
 # end::UPPERDICT[]

15-more-types/protocol/abs_demo.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python3
 
+# tag::ABS_DEMO[]
 import math
 from typing import NamedTuple, SupportsAbs
 
@@ -30,3 +31,4 @@ assert is_unit(v3)
 assert is_unit(v4)
 
 print('OK')
+# end::ABS_DEMO[]

16-op-overloading/vector2d_v3.py

@@ -1,5 +1,5 @@
 """
-A 2-dimensional vector class
+A two-dimensional vector class
 
     >>> v1 = Vector2d(3, 4)
     >>> print(v1.x, v1.y)
@@ -72,7 +72,7 @@ Tests of `x` and `y` read-only properties:
     >>> v1.x = 123
     Traceback (most recent call last):
       ...
-    AttributeError: can't set attribute
+    AttributeError: can't set attribute 'x'
 
 
 Tests of hashing:
@@ -81,7 +81,7 @@ Tests of hashing:
     >>> v2 = Vector2d(3.1, 4.2)
     >>> hash(v1), hash(v2)
     (7, 384307168202284039)
-    >>> len(set([v1, v2]))
+    >>> len({v1, v2})
     2
 
 """
@@ -90,6 +90,8 @@ from array import array
 import math
 
 class Vector2d:
+    __match_args__ = ('x', 'y')
+
     typecode = 'd'
 
     def __init__(self, x, y):

16-op-overloading/vector_v6.py

@@ -305,14 +305,16 @@ class Vector:
         index = operator.index(key)
         return self._components[index]
 
-    shortcut_names = 'xyzt'
+    __match_args__ = ('x', 'y', 'z', 't')
 
     def __getattr__(self, name):
         cls = type(self)
-        if len(name) == 1:
+        try:
-            pos = cls.shortcut_names.find(name)
+            pos = cls.__match_args__.index(name)
-            if 0 <= pos < len(self._components):
+        except ValueError:
-                return self._components[pos]
+            pos = -1
+        if 0 <= pos < len(self._components):
+            return self._components[pos]
         msg = f'{cls.__name__!r} object has no attribute {name!r}'
         raise AttributeError(msg)
 

16-op-overloading/vector_v7.py

@@ -355,14 +355,16 @@ class Vector:
         index = operator.index(key)
         return self._components[index]
 
-    shortcut_names = 'xyzt'
+    __match_args__ = ('x', 'y', 'z', 't')
 
     def __getattr__(self, name):
         cls = type(self)
-        if len(name) == 1:
+        try:
-            pos = cls.shortcut_names.find(name)
+            pos = cls.__match_args__.index(name)
-            if 0 <= pos < len(self._components):
+        except ValueError:
-                return self._components[pos]
+            pos = -1
+        if 0 <= pos < len(self._components):
+            return self._components[pos]
         msg = f'{cls.__name__!r} object has no attribute {name!r}'
         raise AttributeError(msg)
 

16-op-overloading/vector_v8.py

@@ -361,14 +361,16 @@ class Vector:
         index = operator.index(key)
         return self._components[index]
 
-    shortcut_names = 'xyzt'
+    __match_args__ = ('x', 'y', 'z', 't')
 
     def __getattr__(self, name):
         cls = type(self)
-        if len(name) == 1:
+        try:
-            pos = cls.shortcut_names.find(name)
+            pos = cls.__match_args__.index(name)
-            if 0 <= pos < len(self._components):
+        except ValueError:
-                return self._components[pos]
+            pos = -1
+        if 0 <= pos < len(self._components):
+            return self._components[pos]
         msg = f'{cls.__name__!r} object has no attribute {name!r}'
         raise AttributeError(msg)