ch05: new chapter

Author: ramalho

05-record-like/cards.doctest

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+>>> from cards import Card
+>>> helen = Card('Q', 'hearts')
+>>> helen
+Card(rank='Q', suit='hearts')
+
+>>> cards = [Card(r, s) for s in Card.suits for r in Card.ranks]
+>>> cards[:3]
+[Card(rank='2', suit='spades'), Card(rank='3', suit='spades'), Card(rank='4', suit='spades')]
+>>> sorted(cards)[:3]
+[Card(rank='2', suit='clubs'), Card(rank='2', suit='diamonds'), Card(rank='2', suit='hearts')]
+
+>>> from cards_enum import Card, Suit, Rank
+>>> helen = Card('Q', 'hearts')
+>>> helen
+Card(rank='Q', suit='hearts')
+
+>>> cards = [Card(r, s) for s in Suit for r in Rank]
+>>> cards[:3]
+[Card(rank='2', suit='spades'), Card(rank='3', suit='spades'), Card(rank='4', suit='spades')]
+>>> sorted(cards)[:3]
+[Card(rank='2', suit='clubs'), Card(rank='2', suit='diamonds'), Card(rank='2', suit='hearts')]
+>>> for card in cards[12::13]: print(card)

05-record-like/cards.py

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+from dataclasses import dataclass
+
+@dataclass(order=True)
+class Card:
+    rank: str
+    suit: str
+
+    ranks = [str(n) for n in range(2, 10)] + list('JQKA')
+    suits = 'spades diamonds clubs hearts'.split()

05-record-like/cards_enum.py

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+from dataclasses import dataclass
+import enum
+
+Suit = enum.IntEnum('Suit', 'spades diamonds clubs hearts')
+Rank = enum.Enum('Rank', [str(n) for n in range(2, 10)] + list('JQKA'))
+
+@dataclass(order=True)
+class Card:
+    rank: Suit
+    suit: Rank
+
+    def __str__(self):
+        glyphs = [chr(x) for x in range(0x2660, 0x2664)]
+        return f'{self.rank} of {glyphs[self.suit-1]}'

05-record-like/class/coordinates.py

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+"""
+``Coordinate``: a simple class with a custom ``__str__``::
+
+    >>> moscow = Coordinate(55.756, 37.617)
+    >>> print(moscow)  # doctest:+ELLIPSIS
+    <coordinates.Coordinate object at 0x...>
+"""
+
+# tag::COORDINATE[]
+class Coordinate:
+
+    def __init__(self, lat, long):
+        self.lat = lat
+        self.long = long
+
+# end::COORDINATE[]

05-record-like/dataclass/club.py

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

05-record-like/dataclass/club_generic.py

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+from dataclasses import dataclass, field
+from typing import List                              # <1>
+
+@dataclass
+class ClubMember:
+
+    name: str
+    guests: List[str] = field(default_factory=list)  # <2>

05-record-like/dataclass/club_wrong.py

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

05-record-like/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
+    long: float
+        
+    def __str__(self):
+        ns = 'N' if self.lat >= 0 else 'S'
+        we = 'E' if self.long >= 0 else 'W'
+        return f'{abs(self.lat):.1f}°{ns}, {abs(self.long):.1f}°{we}'
+# end::COORDINATE[]

05-record-like/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-record-like/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, Set
+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[]