[Timlinux] Python meta-class

1. Type function

Name ="This is a string"Print(Type (name))#<class ' str ' >Print("*"* 10,"Dividing Line","*"* 10) CLS= Type ('Foo', (), {}) F=CLS ()Print(Type (f))#<class ' __main__. Foo ' >Print(Type (CLS))#<class ' type ' >Print(CLS.__name__)#FooPrint("*"* 10,"Dividing Line","*"* 10)definit (self, Name, age): Self.name=name Self.age= AgePrint(Self.name, self.age) CLS= Type ('Foo', (object,), {'__init__': init}) F= CLS ('Tim', 22)#Tim

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2. __new__ function

classFoo (object):def __init__(self, Name, age): Self.name=name Self.age= AgePrint(Self.name, Self.age)deftmp (self):Print("Call tmp ()")    def __new__(CLS, *args, * *Kwargs):Print("Call __new__") obj= object.__new__(CLS)Print("ID (obj) = = =", id (obj))returnobjf1= Foo ('Tim', 22)#This operation equals the two-step operation below = = =. Print("ID (f1) = = =", ID (F1)) f1.tmp ()#Call __new__#ID (obj) = = = 1507711426120#Tim#ID (f1) = = = 1507711426120#Call tmp ()F2= Foo.__new__(Foo)Print("ID (F2) = = =", ID (F2)) F2.__init__('Tim', 22) f2.tmp ()#Call __new__#ID (obj) = = = 1507711426232#ID (F2) = = = 1507711426232#Tim#Call tmp ()

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3. __init__ function

The __init__ function, if the object is declared by the Foo class, calls the __new__ first, then creates an object by using the Object.__new__ method provided by Python, then returns the object, and then the returned object, which invokes _ _init__ method.

FOO.__NEW__----use this object to invoke the Foo.__init__ method----to complete the object declaration of the class by object.__new__ production object

4. __metaclass__ variables

Ttt

[Timlinux] Python meta-class