update from Atlas

11-iface-abc/bingo.py

@@ -0,0 +1,19 @@
+import random
+
+from tombola import Tombola
+
+
+class BingoCage(Tombola):  # <1>
+
+    def __init__(self, items):
+        self._balls = list(items)  # <2>
+
+    def load(self, items):
+        self._balls.extend(items)
+
+    def pick(self):
+        try:
+            position = random.randrange(len(self._balls))  # <3>
+        except ValueError:
+            raise LookupError('pop from empty BingoCage')
+        return self._balls.pop(position)  # <4>

11-iface-abc/frenchdeck2.py

@@ -0,0 +1,26 @@
+import collections
+
+Card = collections.namedtuple('Card', ['rank', 'suit'])
+
+class FrenchDeck2(collections.MutableSequence):
+    ranks = [str(n) for n in range(2, 11)] + list('JQKA')
+    suits = 'spades diamonds clubs hearts'.split()
+
+    def __init__(self):
+        self._cards = [Card(rank, suit) for suit in self.suits
+                                        for rank in self.ranks]
+
+    def __len__(self):
+        return len(self._cards)
+
+    def __getitem__(self, position):
+        return self._cards[position]
+
+    def __setitem__(self, position, value):  # <1>
+        self._cards[position] = value
+
+    def __delitem__(self, position):  # <2>
+        del self._cards[position]
+
+    def insert(self, position, value):  # <3>
+        self._cards.insert(position, value)

11-iface-abc/lotto.py

@@ -0,0 +1,24 @@
+import random
+
+from tombola import Tombola
+
+
+class LotteryBlower(Tombola):
+
+    def __init__(self, iterable):
+        self.randomizer = random.SystemRandom()  # <1>
+        self.clear()
+        self.load(iterable)
+
+    def clear(self):
+        self._balls = []
+
+    def load(self, iterable):
+        self._balls.extend(iterable)
+        self.randomizer.shuffle(self._balls)  # <2>
+
+    def pick(self):
+        return self._balls.pop()  # <3>
+
+    def loaded(self):  # <4>
+        return len(self._balls) > 0

11-iface-abc/tombola.py

@@ -0,0 +1,23 @@
+import abc
+
+class Tombola(abc.ABC):  # <1>
+
+    @abc.abstractmethod
+    def load(self, iterable):  # <2>
+        """Add items from an iterable."""
+
+    @abc.abstractmethod
+    def pick(self):  # <3>
+        """Remove item at random, returning it.
+
+        This method should raise `LookupError` when the instance is empty.
+        """
+
+    def loaded(self):  # <4>
+        try:
+            item = self.pick()
+        except LookupError:
+            return False
+        else:
+            self.load([item])  # put it back
+            return True

11-iface-abc/tombola_runner.py

@@ -0,0 +1,36 @@
+# BEGIN TOMBOLA_RUNNER
+import doctest
+
+from tombola import Tombola
+
+# modules to test
+import bingo, lotto, tombolist, drum  # <1>
+
+TEST_FILE = 'tombola_tests.rst'
+TEST_MSG = '{0:16} {1.attempted:2} tests, {1.failed:2} failed - {2}'
+
+
+def main(argv):
+    verbose = '-v' in argv
+    real_subclasses = Tombola.__subclasses__()  # <2>
+    virtual_subclasses = list(Tombola._abc_registry)  # <3>
+
+    for cls in real_subclasses + virtual_subclasses:  # <4>
+        test(cls, verbose)
+
+
+def test(cls, verbose=False):
+
+    res = doctest.testfile(
+            TEST_FILE,
+            globs={'ConcreteTombola': cls},  # <5>
+            verbose=verbose,
+            optionflags=doctest.REPORT_ONLY_FIRST_FAILURE)
+    tag = 'FAIL' if res.failed else 'OK'
+    print(TEST_MSG.format(cls.__name__, res, tag))  # <6>
+
+
+if __name__ == '__main__':
+    import sys
+    main(sys.argv)
+# END TOMBOLA_RUNNER

11-iface-abc/tombola_subhook.py

@@ -0,0 +1,64 @@
+"""
+Variation of ``tombola.Tombola`` implementing ``__subclasshook__``.
+
+Tests with simple classes::
+
+    >>> Tombola.__subclasshook__(object)
+    NotImplemented
+    >>> class Complete:
+    ...     def __init__(): pass
+    ...     def load(): pass
+    ...     def pick(): pass
+    ...     def loaded(): pass
+    ...
+    >>> Tombola.__subclasshook__(Complete)
+    True
+    >>> issubclass(Complete, Tombola)
+
+"""
+
+
+from abc import ABC, abstractmethod
+from inspect import getmembers, isfunction
+
+
+class Tombola(ABC):  # <1>
+
+    @abstractmethod
+    def __init__(self, iterable):  # <2>
+        """New instance is loaded from an iterable."""
+
+    @abstractmethod
+    def load(self, iterable):
+        """Add items from an iterable."""
+
+    @abstractmethod
+    def pick(self):  # <3>
+        """Remove item at random, returning it.
+
+        This method should raise `LookupError` when the instance is empty.
+        """
+
+    def loaded(self):  # <4>
+        try:
+            item = self.pick()
+        except LookupError:
+            return False
+        else:
+            self.load([item])  # put it back
+            return True
+
+    @classmethod
+    def __subclasshook__(cls, other_cls):
+        if cls is Tombola:
+            interface_names = function_names(cls)
+            found_names = set()
+            for a_cls in other_cls.__mro__:
+                found_names |= function_names(a_cls)
+            if found_names >= interface_names:
+                return True
+        return NotImplemented
+
+
+def function_names(obj):
+    return {name for name, _ in getmembers(obj, isfunction)}

11-iface-abc/tombola_tests.rst

@@ -0,0 +1,80 @@
+==============
+Tombola tests
+==============
+
+Every concrete subclass of Tombola should pass these tests.
+
+
+Create and load instance from iterable::
+
+    >>> balls = list(range(3))
+    >>> globe = ConcreteTombola(balls)
+    >>> globe.loaded()
+    True
+
+
+Pick and collect balls::
+
+    >>> picks = []
+    >>> picks.append(globe.pick())
+    >>> picks.append(globe.pick())
+    >>> picks.append(globe.pick())
+
+
+Check state and results::
+
+    >>> globe.loaded()
+    False
+    >>> sorted(picks) == balls
+    True
+
+
+Reload::
+
+    >>> globe.load(balls)
+    >>> globe.loaded()
+    True
+    >>> picks = [globe.pick() for i in balls]
+    >>> globe.loaded()
+    False
+
+
+Check that `LookupError` (or a subclass) is the exception
+thrown when the device is empty::
+
+    >>> globe = ConcreteTombola([])
+    >>> try:
+    ...     globe.pick()
+    ... except LookupError as exc:
+    ...     print('OK')
+    OK
+
+
+Load and pick 100 balls to verify that they all come out::
+
+    >>> balls = list(range(100))
+    >>> globe = ConcreteTombola(balls)
+    >>> picks = []
+    >>> while globe.loaded():
+    ...     picks.append(globe.pick())
+    >>> len(picks) == len(balls)
+    True
+    >>> set(picks) == set(balls)
+    True
+
+
+Check that the order has changed and is not simply reversed::
+
+    >>> picks != balls
+    True
+    >>> picks[::-1] != balls
+    True
+
+Note: the previous 2 tests have a *very* small chance of failing
+even if the implementation is OK. The probability of the 100
+balls coming out, by chance, in the order they were loaded is
+1/100!, or approximately 1.07e-158. It's much easier to win the
+Lotto or to become a billionaire working as a programmer.
+
+THE END
+

11-iface-abc/tombolist.py

@@ -0,0 +1,19 @@
+from random import randrange
+
+from tombola import Tombola
+
+@Tombola.register  # <1>
+class TomboList(list):  # <2>
+
+    def pick(self):
+        if self:  # <3>
+            position = randrange(len(self))
+            return self.pop(position)  # <4>
+        else:
+            raise LookupError('pop from empty TomboList')
+
+    def load(self, iterable): self.extend(iterable)  # <5>
+
+    def loaded(self): return bool(self)  # <6>
+
+# Tombola.register(TomboList)  # <- Python 3.2 or earlier