3.5. OOP Method Access Modifiers¶
Attributes and methods are always public
No protected and private keywords
Protecting is only by convention [1]
name(self)- public method_name(self)- protected method (non-public by convention)__name(self)- private method (name mangling)__name__(self)- system methodname_(self)- avoid name collision
3.5.1. Protected Method¶
>>> from dataclasses import dataclass
>>>
>>>
>>> @dataclass
... class Astronaut:
... _firstname: str
... _lastname: str
...
... def _get_fullname(self):
... return f'{self._firstname} {self._lastname}'
...
... def get_publicname(self):
... return f'{self._firstname} {self._lastname[0]}.'
>>>
>>>
>>> mark = Astronaut('Mark', 'Watney')
>>> mark._get_fullname() # IDE should warn: "Access to a protected member _get_fullname of a class"
'Mark Watney'
3.5.2. Private Method¶
>>> class Astronaut:
... def __init__(self, firstname, lastname):
... self._firstname = firstname
... self._lastname = lastname
...
... def __get_fullname(self):
... return f'{self._firstname} {self._lastname}'
...
... def get_publicname(self):
... return f'{self._firstname} {self._lastname[0]}.'
>>>
>>>
>>> mark = Astronaut('Mark', 'Watney')
>>>
>>> mark.__get_fullname()
Traceback (most recent call last):
AttributeError: 'Astronaut' object has no attribute '__get_fullname'
>>>
>>> mark._Astronaut__get_fullname() # IDE should warn: "Access to a protected member _Astronaut__get_fullname of a class"
'Mark Watney'
3.5.3. System Method¶
>>> class Astronaut:
... def __init__(self, firstname, lastname):
... self._firstname = firstname
... self._lastname = lastname
...
... def __str__(self):
... return 'stringification'
...
... def __repr__(self):
... return 'representation'
>>>
>>>
>>> mark = Astronaut('Mark', 'Watney')
>>>
>>> print(str(mark))
stringification
>>>
>>> print(repr(mark))
representation
3.5.4. Show Methods¶
dir()
>>> class Astronaut:
... def __init__(self, firstname, lastname):
... self._firstname = firstname
... self._lastname = lastname
...
... def __get_fullname(self):
... return f'{self._firstname} {self._lastname}'
...
... def get_publicname(self):
... return f'{self._firstname} {self._lastname[0]}.'
>>>
>>>
>>> mark = Astronaut('Mark', 'Watney')
>>>
>>> print(dir(mark))
['_Astronaut__get_fullname', '__class__', '__delattr__', '__dict__',
'__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__',
'__getstate__', '__gt__', '__hash__', '__init__', '__init_subclass__',
'__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__',
'__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__',
'__subclasshook__', '__weakref__', '_firstname', '_lastname',
'get_publicname']
>>>
>>> [method for method in dir(mark) if callable(getattr(mark, method))]
['_Astronaut__get_fullname', '__class__', '__delattr__', '__dir__',
'__eq__', '__format__', '__ge__', '__getattribute__', '__getstate__',
'__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__',
'__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__',
'__setattr__', '__sizeof__', '__str__', '__subclasshook__',
'get_publicname']
>>>
>>> public_methods = [method
... for method in dir(mark)
... if callable(getattr(mark, method))
... and not method.startswith('_')]
>>>
>>> protected_methods = [method
... for method in dir(mark)
... if callable(getattr(mark, method))
... and method.startswith('_')]
>>>
>>> private_methods = [method
... for method in dir(mark)
... if callable(getattr(mark, method))
... and method.startswith(f'_{mark.__class__.__name__}')]
>>>
>>> system_methods = [method
... for method in dir(mark)
... if callable(getattr(mark, method))
... and method.startswith(f'__')
... and method.endswith(f'__')]