Day8 Object-oriented (supplemental)

Private fields

Class Foo:

    def __init__ (self, name):
        Self.__name = Name

    def F1 (self):
        Print (Self.__name)

Class Bar (Foo):
    def f2 (self):
        Print (Self.__name)

obj = Foo (' Alex ')
#print (Obj.name)
#只能内部调用
OBJ.F1 ()

Obj2 = Bar (' aaa ')
OBJ2.F1 ()
#私有普通字段只有自己能访问, the rest is not.
OBJ2.F2 ()

Static methods

Class Foo:

    __CC = ' 123 '
    def __init__ (self, name):
        Self.__name = Name

    def F1 (self):
        Print (Self.__name)

    @staticmethod
    def f2 ():
        Print (FOO.__CC)

# obj = Foo (' aaa ')
# OBJ.F2 ()
FOO.F2 ()

__getitem,__setitem,__delitem

Class Foo:

    def __init__ (self, name):
        Self.__name = Name

    def F1 (self):
        Print (Self.__name)

    def __getitem__ (self, item):
        Print (Type (item))
        Return 123

    def __setitem__ (self, Key, value):
        Print (' SetItem ')

    def __delitem__ (self, key):
        Print (' del item ')

obj = Foo (' Alex ')
#obj [] Execute __getitem__ method
#语法对应关系
ret = obj[' ad ']
Print (ret)
Ret1 = Obj[1:2]
Print (RET1)
obj[' k1 '] = 123
Del obj[' K1 ']

Slice

Class Foo:

    def __init__ (self, name):
        Self.__name = Name

    def F1 (self):
        Print (Self.__name)

    def __getitem__ (self, item):
        Print (item, type (item))
        Print (Item.Start)
        Print (Item.stop)
        Print (Item.step)
        Return 123

    def __setitem__ (self, Key, value):
        #key. Start  key.stop  key.step
        Print (Type (key), type (value))

    def __delitem__ (self, key):
        Print (Type (key))
        # Key.start  key.stop  key.step
        Print (' del item ')

obj = Foo (' Alex ')
#obj [] Execute __getitem__ method
#语法对应关系
#ret = obj[' ad ']
Ret1 = Obj[1:4:2]
Obj[1:4] = [11, 22, 33, 44, 55]
Del Obj[1:4]

Iterators

Class Foo:
    def __iter__ (self):
        Yield 1
        Yield 2

obj = Foo ()
For item in obj:
    Print (item)

#1. obj can be looped and must be iterated
The __iter__ method is executed by default when the For loop executes #2.

Isinstance and Issubclass

#isinstance: Instance of obj, Foo (parent class of obj type and obj type)
#issubclass: Whether the child class
Class Foo:
    Pass

Class Bar (Foo):
    Pass

obj = Bar ()
ret = isinstance (obj, Foo)
Print (ret)

Ret2 = Issubclass (Bar, Foo)
Print (Ret2)

Super

#假设有一大堆代码, it is now necessary to add functionality without changing the original code structure based on the addition of class
#然后执行super方法, super actively executes the method of the parent class
Class C1:
    def F1 (self):
        Print (' C1.f1 ')

Class C2 (C1):
    def F1 (self):
        #主动去执行父类的f1方法
        Super (C2, self). F1 ()
        Print (' C2.f1 ')
        #不建议使用该方法
        #C1. F1 (self)

obj = C2 ()
OBJ.F1 ()

On the basis of not changing the original frame, add the method

Frame structure:

Test

    Backend

           commons.py

    index.py

    lib.py (self-expanding class)

    settings.py

commons.py

Class Foo:

    def F1 (self):
        Print (' Foo.f1 ')

settings.py

# Path = ' backend.commons '
# ClassName = ' Foo '

Path = ' lib '
ClassName = ' Myfoo '

lib.py

From backend.commons import Foo

Class Myfoo (Foo):
    def f2 (self):
        Print ("before")
        Super (Myfoo, self). F1 ()
        Print ("after")

index.py

From Settings Import ClassName
From Settings Import Path

def execute ():
    #print (ClassName)
    #反射获取字符串
    Model = __import__ (Path, Fromlist=true)
    CLS = GetAttr (model, ClassName)
    obj = CLS ()
    OBJ.F2 ()

if __name__ = = ' __main__ ':
    Execute ()

Ordered dictionaries

Class Mydict (Dict):

    def __init__ (self):
        Self.li = []
        Super (mydict, self). __init__ ()

    def __setitem__ (self, Key, value):
        Self.li.append (Key)
        Super (mydict, self). __setitem__ (key, value)

    def __str__ (self):
        Tmp_list = []
        For key in Self.li:
            Value = Self.get (key)
            Tmp_list.append ("'%s ':%s"% (key, value))
        Tmp_str = "{" + ",". Join (Tmp_list) + "}"
        Return TMP_STR


obj = Mydict ()
obj[' k1 '] = 123
obj[' K2 '] = 345
Print (obj)

Day8 Object-oriented (supplemental)