python3面向对象类的内置属性与方法

桃扇骨 2022-04-18 05:48 303阅读 0赞

# 0.object类源码 #

class object:
        """ The most base type """
        def __delattr__(self, *args, **kwargs): # real signature unknown
            """ Implement delattr(self, name). """
            pass
    
        def __dir__(self): # real signature unknown; restored from __doc__
            """
            __dir__() -> list
            default dir() implementation
            """
            return []
    
        def __eq__(self, *args, **kwargs): # real signature unknown
            """ Return self==value. """
            pass
    
        def __format__(self, *args, **kwargs): # real signature unknown
            """ default object formatter """
            pass
    
        def __getattribute__(self, *args, **kwargs): # real signature unknown
            """ Return getattr(self, name). """
            pass
    
        def __ge__(self, *args, **kwargs): # real signature unknown
            """ Return self>=value. """
            pass
    
        def __gt__(self, *args, **kwargs): # real signature unknown
            """ Return self>value. """
            pass
    
        def __hash__(self, *args, **kwargs): # real signature unknown
            """ Return hash(self). """
            pass
    
        def __init_subclass__(self, *args, **kwargs): # real signature unknown
            """
            This method is called when a class is subclassed.
            
            The default implementation does nothing. It may be
            overridden to extend subclasses.
            """
            pass
    
        def __init__(self): # known special case of object.__init__
            """ Initialize self.  See help(type(self)) for accurate signature. """
            pass
    
        def __le__(self, *args, **kwargs): # real signature unknown
            """ Return self<=value. """
            pass
    
        def __lt__(self, *args, **kwargs): # real signature unknown
            """ Return self<value. """
            pass
    
        @staticmethod # known case of __new__
        def __new__(cls, *more): # known special case of object.__new__
            """ Create and return a new object.  See help(type) for accurate signature. """
            pass
    
        def __ne__(self, *args, **kwargs): # real signature unknown
            """ Return self!=value. """
            pass
    
        def __reduce_ex__(self, *args, **kwargs): # real signature unknown
            """ helper for pickle """
            pass
    
        def __reduce__(self, *args, **kwargs): # real signature unknown
            """ helper for pickle """
            pass
    
        def __repr__(self, *args, **kwargs): # real signature unknown
            """ Return repr(self). """
            pass
    
        def __setattr__(self, *args, **kwargs): # real signature unknown
            """ Implement setattr(self, name, value). """
            pass
    
        def __sizeof__(self): # real signature unknown; restored from __doc__
            """
            __sizeof__() -> int
            size of object in memory, in bytes
            """
            return 0
    
        def __str__(self, *args, **kwargs): # real signature unknown
            """ Return str(self). """
            pass
    
        @classmethod # known case
        def __subclasshook__(cls, subclass): # known special case of object.__subclasshook__
            """
            Abstract classes can override this to customize issubclass().
            
            This is invoked early on by abc.ABCMeta.__subclasscheck__().
            It should return True, False or NotImplemented.  If it returns
            NotImplemented, the normal algorithm is used.  Otherwise, it
            overrides the normal algorithm (and the outcome is cached).
            """
            pass
    
        __class__ = None # (!) forward: type, real value is ''
        __dict__ = {}
        __doc__ = ''
        __module__ = ''

# 1.常用内置属性说明 #

> ①**\_\_class\_\_**:说明对象处于哪一个模块中的哪一个类
> 
> ②**\[类名\].\_\_dict\_\_**:打印类的所有属性与方法(包括继承自基类的属性和方法)（包括内置属性和方法）
> 
>    **\[对象\].\_\_dict\_\_**:打印对象的所有属性（私有和公有）
> 
> ③**\[类名\].\_\_doc\_\_**:打印类的注释
> 
> ④**\[对象\].\_\_module\_\_**:打印对象所在模块

### myTime.py ###

import time
    
    class MyTime(object):
        at = "MyTime Class"
    
        def now_time(self):
            print(time.time())

### main.py ###

from myTime import MyTime
    
    
    class Cat(object):
        """这是一个猫类"""
        ac = "Cat class"
    
        def __init__(self, name, count):
            self.name = name
            self.__count = count
    
        def tell(self):
            print(self.name)
    
    
    class Dog(Cat):
        ad = "Dog Class"
    
        def __init__(self, name, count, sex):
            super(Dog, self).__init__(name, count)
            self.sex = sex
    
        def haha(self):
            print("Dog haha")
    
    
    if "__main__" == __name__:
    
        c = Cat("miao", 12)
        d = Dog("xiaogou", 12, "female")
    
        t = MyTime()
    
        print(c.__class__)  # <class '__main__.Cat'>
        print(t.__class__)  # <class 'myTime.MyTime'>
        print(Cat.__dict__)
        print(d.__dict__)
        print(c.__doc__)  # 这是一个猫类
        print(d.__doc__)  # None
        print(c.__module__)  # __main__
        print(d.__module__)  # __main__
        print(t.__module__)  # myTime

# 3.内置方法说明 #

> ①**\_\_new\_\_:**在\_\_init\_\_函数之前执行，创建并返回一个新的对象。利用这个方法和类属性的特性可以实现设计模式中的**单例模式**。

class SingleItem(object):
        __instance = None
    
        def __init__(self):
            print("__init__")
    
        def __new__(cls, *args, **kwargs):
            print("__new__")
    
            if cls.__instance == None:
                cls.__instance = object.__new__(cls, *args, *kwargs)
    
            return cls.__instance
    
        def show(self):
            print(self.__instance)
    
    
    if "__main__" == __name__:
        
        s1 = SingleItem()
        s1.show()  # <__main__.SingleItem object at 0x000001A309BD7E48>
        s2 = SingleItem()
        s2.show()  # <__main__.SingleItem object at 0x000001A309BD7E48>

> ②**\_\_str\_\_**: 在使用print语句时被调用。

class Test(object):
        __name = "__name"
        __age = "__age"
    
        def __init__(self, name, age):
            self.name = name
            self.age = age
    
        def __str__(self):
            return self.__name
    
    
    if "__main__" == __name__:
    
        s1 = Test("maxin", 23)
        print(s1)
        print(str(s1))

> ③**\_\_call\_\_**: 将实例对象作为函数调用（也就是需要加（））

class Fruit(object):
        class Growth(object):
            def __call__(self, *args, **kwargs):
                print("growth...")
    
        growth = Growth()
    
    
    if "__main__" == __name__:
        f1 = Fruit()
        f1.growth()
        Fruit.growth()

> ④**\_\_getitem,\_\_setitem,\_\_delitem**: 将类封装成一个字典的形式

class Person(object):
        def __init__(self, name):
            self.name = name
            self.dict = {}
    
        def __getitem__(self, item):
            if item in self.dict:
                return self.dict[item]
            else:
                return None
    
        def __setitem__(self, key, value):
            self.dict[key] = value
    
        def __delitem__(self, key):
            print("__delitem__")
    
    
    if "__main__" == __name__:
    
        p1 = Person("maxin")
        print(p1["age"])
        p1["age"] = 23
        print(p1["age"])
        del p1["age"]  # __delitem__
        print(p1["age"])