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05-data-classes/dataclass/club.py

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

05-data-classes/dataclass/club_generic.py

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+from dataclasses import dataclass, field
+
+@dataclass
+class ClubMember:
+    name: str
+    guests: list[str] = field(default_factory=list)  # <1>

05-data-classes/dataclass/club_wrong.py

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

05-data-classes/dataclass/coordinates.py

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+"""
+``Coordinate``: simple class decorated with ``dataclass`` and a custom ``__str__``::
+
+    >>> moscow = Coordinate(55.756, 37.617)
+    >>> print(moscow)
+    55.8°N, 37.6°E
+
+"""
+
+# tag::COORDINATE[]
+
+from dataclasses import dataclass
+
+@dataclass(frozen=True)
+class Coordinate:
+    lat: float
+    lon: float
+
+    def __str__(self):
+        ns = 'N' if self.lat >= 0 else 'S'
+        we = 'E' if self.lon >= 0 else 'W'
+        return f'{abs(self.lat):.1f}°{ns}, {abs(self.lon):.1f}°{we}'
+# end::COORDINATE[]

05-data-classes/dataclass/hackerclub.py

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+# tag::DOCTESTS[]
+"""
+``HackerClubMember`` objects accept an optional ``handle`` argument::
+
+    >>> anna = HackerClubMember('Anna Ravenscroft', handle='AnnaRaven')
+    >>> anna
+    HackerClubMember(name='Anna Ravenscroft', guests=[], handle='AnnaRaven')
+
+If ``handle`` is ommitted, it's set to the first part of the member's name::
+
+    >>> leo = HackerClubMember('Leo Rochael')
+    >>> leo
+    HackerClubMember(name='Leo Rochael', guests=[], handle='Leo')
+
+Members must have a unique handle. The following ``leo2`` will not be created,
+because its ``handle`` would be 'Leo', which was taken by ``leo``::
+
+    >>> leo2 = HackerClubMember('Leo DaVinci')
+    Traceback (most recent call last):
+      ...
+    ValueError: handle 'Leo' already exists.
+
+To fix, ``leo2`` must be created with an explicit ``handle``::
+
+    >>> leo2 = HackerClubMember('Leo DaVinci', handle='Neo')
+    >>> leo2
+    HackerClubMember(name='Leo DaVinci', guests=[], handle='Neo')
+"""
+# end::DOCTESTS[]
+
+# tag::HACKERCLUB[]
+from dataclasses import dataclass
+from club import ClubMember
+
+@dataclass
+class HackerClubMember(ClubMember):                         # <1>
+
+    all_handles = set()                                     # <2>
+
+    handle: str = ''                                        # <3>
+
+    def __post_init__(self):
+        cls = self.__class__                                # <4>
+        if self.handle == '':                               # <5>
+            self.handle = self.name.split()[0]
+        if self.handle in cls.all_handles:                  # <6>
+            msg = f'handle {self.handle!r} already exists.'
+            raise ValueError(msg)
+        cls.all_handles.add(self.handle)                    # <7>
+# end::HACKERCLUB[]

05-data-classes/dataclass/hackerclub_annotated.py

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+# tag::DOCTESTS[]
+"""
+``HackerClubMember`` objects can be created with a ``name`` and an optional ``handle``::
+
+    >>> anna = HackerClubMember('Anna Ravenscroft', handle='AnnaRaven')
+    >>> anna
+    HackerClubMember(name='Anna Ravenscroft', guests=[], handle='AnnaRaven')
+
+If ``handle`` is ommitted, it's set to the first part of the member's name::
+
+    >>> leo = HackerClubMember('Leo Rochael')
+    >>> leo
+    HackerClubMember(name='Leo Rochael', guests=[], handle='Leo')
+
+Members must have a unique handle. This ``leo2`` will not be created,
+because its ``handle`` would be 'Leo', which was taken by ``leo``::
+
+    >>> leo2 = HackerClubMember('Leo DaVinci')
+    Traceback (most recent call last):
+      ...
+    ValueError: handle 'Leo' already exists.
+
+To fix, ``leo2`` must be created with an explicit ``handle``::
+
+    >>> leo2 = HackerClubMember('Leo DaVinci', handle='Neo')
+    >>> leo2
+    HackerClubMember(name='Leo DaVinci', guests=[], handle='Neo')
+"""
+# end::DOCTESTS[]
+
+# tag::HACKERCLUB[]
+from dataclasses import dataclass
+from typing import ClassVar
+from club import ClubMember
+
+@dataclass
+class HackerClubMember(ClubMember):
+
+    all_handles: ClassVar[set[str]] = set()
+
+    handle: str = ''
+
+    def __post_init__(self):
+        cls = self.__class__
+        if self.handle == '':
+            self.handle = self.name.split()[0]
+        if self.handle in cls.all_handles:
+            msg = f'handle {self.handle!r} already exists.'
+            raise ValueError(msg)
+        cls.all_handles.add(self.handle)
+# end::HACKERCLUB[]

05-data-classes/dataclass/resource.py

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+"""
+Media resource description class with subset of the Dublin Core fields.
+
+Default field values:
+
+    >>> r = Resource('0')
+    >>> r  # doctest: +NORMALIZE_WHITESPACE
+    Resource(identifier='0', title='<untitled>', creators=[], date=None,
+    type=<ResourceType.BOOK: 1>, description='', language='', subjects=[])
+
+A complete resource record:
+# tag::DOCTEST[]
+
+    >>> description = 'Improving the design of existing code'
+    >>> book = Resource('978-0-13-475759-9', 'Refactoring, 2nd Edition',
+    ...     ['Martin Fowler', 'Kent Beck'], date(2018, 11, 19),
+    ...     ResourceType.BOOK, description, 'EN',
+    ...     ['computer programming', 'OOP'])
+    >>> book  # doctest: +NORMALIZE_WHITESPACE
+    Resource(identifier='978-0-13-475759-9', title='Refactoring, 2nd Edition',
+    creators=['Martin Fowler', 'Kent Beck'], date=datetime.date(2018, 11, 19),
+    type=<ResourceType.BOOK: 1>, description='Improving the design of existing code',
+    language='EN', subjects=['computer programming', 'OOP'])
+
+# end::DOCTEST[]
+"""
+
+# tag::DATACLASS[]
+from dataclasses import dataclass, field
+from typing import Optional
+from enum import Enum, auto
+from datetime import date
+
+
+class ResourceType(Enum):                              # <1>
+    BOOK = auto()
+    EBOOK = auto()
+    VIDEO = auto()
+
+
+@dataclass
+class Resource:
+    """Media resource description."""
+    identifier: str                                    # <2>
+    title: str = '<untitled>'                          # <3>
+    creators: list[str] = field(default_factory=list)
+    date: Optional[date] = None                        # <4>
+    type: ResourceType = ResourceType.BOOK             # <5>
+    description: str = ''
+    language: str = ''
+    subjects: list[str] = field(default_factory=list)
+# end::DATACLASS[]
+
+
+from typing import TypedDict
+
+
+class ResourceDict(TypedDict):
+    identifier: str
+    title: str
+    creators: list[str]
+    date: Optional[date]
+    type: ResourceType
+    description: str
+    language: str
+    subjects: list[str]
+
+
+if __name__ == '__main__':
+    r = Resource('0')
+    description = 'Improving the design of existing code'
+    book = Resource('978-0-13-475759-9', 'Refactoring, 2nd Edition',
+                    ['Martin Fowler', 'Kent Beck'], date(2018, 11, 19),
+                    ResourceType.BOOK, description,
+                    'EN', ['computer programming', 'OOP'])
+    print(book)
+    book_dict: ResourceDict = {
+        'identifier': '978-0-13-475759-9',
+        'title': 'Refactoring, 2nd Edition',
+        'creators': ['Martin Fowler', 'Kent Beck'],
+        'date': date(2018, 11, 19),
+        'type': ResourceType.BOOK,
+        'description': 'Improving the design of existing code',
+        'language': 'EN',
+        'subjects': ['computer programming', 'OOP']}
+    book2 = Resource(**book_dict)
+    print(book == book2)

05-data-classes/dataclass/resource_repr.py

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+"""
+Media resource description class with subset of the Dublin Core fields.
+
+Default field values:
+
+    >>> r = Resource('0')
+    >>> r  # doctest: +NORMALIZE_WHITESPACE
+    Resource(
+        identifier = '0',
+        title = '<untitled>',
+        creators = [],
+        date = None,
+        type = <ResourceType.BOOK: 1>,
+        description = '',
+        language = '',
+        subjects = [],
+    )
+
+A complete resource record:
+
+    >>> description = 'Improving the design of existing code'
+    >>> book = Resource('978-0-13-475759-9', 'Refactoring, 2nd Edition',
+    ...     ['Martin Fowler', 'Kent Beck'], date(2018, 11, 19),
+    ...     ResourceType.BOOK, description, 'EN',
+    ...     ['computer programming', 'OOP'])
+
+# tag::DOCTEST[]
+    >>> book  # doctest: +NORMALIZE_WHITESPACE
+    Resource(
+        identifier = '978-0-13-475759-9',
+        title = 'Refactoring, 2nd Edition',
+        creators = ['Martin Fowler', 'Kent Beck'],
+        date = datetime.date(2018, 11, 19),
+        type = <ResourceType.BOOK: 1>,
+        description = 'Improving the design of existing code',
+        language = 'EN',
+        subjects = ['computer programming', 'OOP'],
+    )
+
+# end::DOCTEST[]
+"""
+
+from dataclasses import dataclass, field, fields
+from typing import Optional, TypedDict
+from enum import Enum, auto
+from datetime import date
+
+
+class ResourceType(Enum):
+    BOOK = auto()
+    EBOOK = auto()
+    VIDEO = auto()
+
+
+@dataclass
+class Resource:
+    """Media resource description."""
+    identifier: str
+    title: str = '<untitled>'
+    creators: list[str] = field(default_factory=list)
+    date: Optional[date] = None
+    type: ResourceType = ResourceType.BOOK
+    description: str = ''
+    language: str = ''
+    subjects: list[str] = field(default_factory=list)
+
+# tag::REPR[]
+    def __repr__(self):
+        cls = self.__class__
+        cls_name = cls.__name__
+        indent = ' ' * 4
+        res = [f'{cls_name}(']                            # <1>
+        for f in fields(cls):                             # <2>
+            value = getattr(self, f.name)                 # <3>
+            res.append(f'{indent}{f.name} = {value!r},')  # <4>
+
+        res.append(')')                                   # <5>
+        return '\n'.join(res)                             # <6>
+# end::REPR[]
+
+
+class ResourceDict(TypedDict):
+    identifier: str
+    title: str
+    creators: list[str]
+    date: Optional[date]
+    type: ResourceType
+    description: str
+    language: str
+    subjects: list[str]
+
+
+if __name__ == '__main__':
+    r = Resource('0')
+    description = 'Improving the design of existing code'
+    book = Resource('978-0-13-475759-9', 'Refactoring, 2nd Edition',
+                    ['Martin Fowler', 'Kent Beck'], date(2018, 11, 19),
+                    ResourceType.BOOK, description,
+                    'EN', ['computer programming', 'OOP'])
+    print(book)
+    book_dict: ResourceDict = {
+        'identifier': '978-0-13-475759-9',
+        'title': 'Refactoring, 2nd Edition',
+        'creators': ['Martin Fowler', 'Kent Beck'],
+        'date': date(2018, 11, 19),
+        'type': ResourceType.BOOK,
+        'description': 'Improving the design of existing code',
+        'language': 'EN',
+        'subjects': ['computer programming', 'OOP']}
+    book2 = Resource(**book_dict)
+    print(book == book2)