example-code-2e/05-data-classes/dataclass/hackerclub_annotated.py
2021-09-15 22:48:08 -03:00

50 lines
1.5 KiB
Python

# 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 omitted, 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[]