其他方法汇总

__repr__(self)

class Dog():
    def __init__(self, name):
        self.name = name
    # 实例描述(调试和开发用)
    # 如果不重写__repr__() 
    # print(my_dog)
    # 返回<类名+object at+内存地址>
    # 返回<__main__.Dog object at 0x000001C4AFE1A164>
    def __repr__(self):
        return f'<Dog类{self.name}>__repr__......'
if __name__ == "__main__":
    my_dog = Dog('A')
    print(my_dog)

<Dog类A>__repr__......

__str__(self)

class Dog():
    def __init__(self, name):
        self.name = name
    # 实例描述(为最终用户创建输出)
    # 如果不重写__str__() 
    # print(my_dog)
    # 返回<类名+object at+内存地址>
    # 返回<__main__.Dog object at 0x000001C4AFE1A164>
    def __str__(self):
        return f'<Dog类{self.name}>__str__'
if __name__ == "__main__":
    my_dog = Dog('A')
    print(my_dog)

<Dog类A>__str__

__bytes__(self)

__hash__(self)

__bool__(self)

__format__(self, format_spec)

In [6]: _formats = {'ymd' : '{d.year}-{d.month}-{d.day}',
   ...:             'mdy' : '{d.month}/{d.day}/{d.year}'}
In [12]: class Date:
    ...:     def __init__(self, year, month, day):
    ...:         self.year = year
    ...:         self.month = month
    ...:         self.day = day
    ...:     def __format__(self, code):
    ...:         if code == '':
    ...:             code ='ymd'
    ...:         fmt = _formats[code]
    ...:         return fmt.format(d=self)
In [14]: d = Date(2018, 8, 8)
In [15]: format(d)
Out[15]: '2018-8-8'

__getattr__(self, name)、__getattribute__(self, name)、__setattr__(self, name, value)、__delattr__(self, name)

class Dog():
    def __init__(self, name):
        self.name = name
        self.age = 0
    # 定义了可以控制属性
    # print(my_dog.name)
    def __getattr__(self, attr):
        if attr in ('name', 'age', 'score'):
            super().__getattr__(attr)
            return attr
        else:
            return None
    # 定义了可以控制属性
    # print(my_dog.name = "new_name")
    # print(my_dog.name)
    def __setattr__(self, name, value):
        print("__setattr__:"+str(name)+":"+str(value))
        super().__setattr__(name, value)
    # 定义了可以控制属性
    def __delattr__(self, name):
        print("__delattr__"+":"+str(name))
        super().__delattr__(name)
if __name__ == "__main__":
    my_dog = Dog('A')  # __setattr__:name:A
                       # __setattr__:age:0
    my_dog.age = 3     # __setattr__:age:3
    print(my_dog.name) # A
    print(my_dog.names) # None
    print(my_dog.age)  # age
    del my_dog.age     # __delattr__:age
    print(my_dog.age)  # 报错

__dir__(self)

__get__(self, instance, owner)

__set__(self, instance, value)

__delete__(self, instance)

__enter__(self)

__exit__(self, exc_type, exc_value, traceback)

__getitem__(self, key)

__setitem__(self, key, value)

__delitem__(self, key)

__iter__(self)

__reversed__(self)

__eq__(self, other)

__ne__(self, other)

__divmod__(self, other)

__pow__(self, other[, modulo])

__lshift__(self, other)

__rshift__(self, other)

__and__(self, other)

__xor__(self, other)

__or__(self, other)

__radd__(self, other)

__rsub__(self, other)

__rtruediv__(self, other)

__rfloordiv__(self, other)

__rmod__(self, other)

__rdivmod__(self, other)

__rpow__(self, other)

__rlshift__(self, other)

__rrshift__(self, other)

__rand__(self, other)

__rxor__(self, other)

__ror__(self, other)

__iadd__(self, other)

__isub__(self, other)

__imul__()、__mul__()、__rmul__()

import numpy as np
a = np.reshape(np.arange(1, 5), (2, 2))
b = np.reshape(np.arange(4, 0, -1), (2, 2))
"""
a:
[[1 2] 
[3 4]]
b:
[[4 3]
[2 1]]
"""
print(a.__matmul__(b))
print(a.__rmatmul__(b))
输出结果为：
[[ 8  5]
 [20 13]]
[[13 20]
 [ 5  8]]

可以看到，a.matmul(b)的作用就是返回a、b矩阵乘积的结果，而a.rmatmul(b)返回的是b、a矩阵乘积的结果。

a.matmul(b)的作用跟np.matmul(a, b)相同，而a.rmatmul(b)的作用与np.matmul(b, a)相同。

然后，imatmul()函数在我使用的python3.8版本中已经取消。

取而代之的是imul()函数，同时，还有mul()、rmul()，这三个函数的作用相同，都是计算a与b矩阵的内积，这也是字母i的含义，i表示in-place
测试代码如下：

print(a.__rmul__(b))
print(a.__mul__(b))
print(a.__imul__(b))
输出结果为：
[[4 6]
 [6 4]]
[[4 6]
 [6 4]]
[[4 6]
 [6 4]]

__itruediv__(self, other)

__ifloordiv__(self, other)

__imod__(self, other)

__ipow__(self, other[, modulo])

__ilshift__(self, other)

__irshift__(self, other)

__iand__(self, other)

__ixor__(self, other)

__ior__(self, other)

__pos__(self)

__neg__(self)

__abs__(self)

__invert__(self)

__complex__(self)

__int__(self)

__float__(self)

__round__(self)

__index__(self)

__next__()

__delslice__()、__getslice__()、__setslice__()增加切片功能

只限python2.x版本，python3.x无此功能

## coding=utf-8
class Foo(object):
    save_list = [1, 2, 3, 4, 5, 6, 34, 23, 5]
    def __getslice__(self, i, j):
        print "__getslice__:"
        return self.save_list[i: j]
    def __setslice__(self, i, j, sequence):
        print "__setslice__:"
        self.save_list[i:j] = sequence
        print self.save_list
    def __delslice__(self, i, j):
        print "__delslice__:"
        del self.save_list[i: j]
        print self.save_list
obj = Foo()
result = obj[1: 2]
print(result)
obj[0: 1] = [23, 22, 15, 4]
del obj[4:]
"""
结果：
__getslice__:
[2]
__setslice__:
[23, 22, 15, 4, 2, 3, 4, 5, 6, 34, 23, 5]
__delslice__:
[23, 22, 15, 4]
"""

__reduce__()

__reduce_ex__()

__subclasshook__()