The advanced object-oriented learning of Python learning

First, the property attribute advanced usage can use an object method as a property Example: class foo:    def __init__ (self, age):         )         self.__age  = age     @property     def age (self):         return self.__age     @age .setter     def age (Self, args):        self.__age =  args     @age. Deleter    def age (self):         del self.__ageobj = foo print (obj.age) obj.age = 3print ( Obj.age) Del obj.ageprint (obj.age) class foo:    def __init__ (self, age) :        self.__age = age    def  Get_age (self):    &NBsp;    return self.__age    def set_age (Self, args):         self.__age = args    def  Del_age (self):         del self.__age    age  = property (Get_age, set_age, del_age) Obj = foo () print (obj.age) obj.age =  3print (obj.age) del obj.ageprint (obj.age) __str__ method, default return object memory address, can modify the override default Method Example:class foo:     def __init__ (self, name, age):         self.name = name        self.age = age     def __str__ (self):        return  ' name:  %s, age: %s '  % (self.name, self.age) obj = foo (' Egon ',  ') print (obj) _ _GETITEM__, __SETITEM__,__delitem__ can call properties and method examples by way of a dictionary: class foo:    def __init__ (self, name):         self.name = name    def __getitem __ (Self, item):         print ("GetItem")          return self.__dict__[item]    def __setitem__ (Self,  key, value):         print ("SetItem",  key, value)         self.__dict__[key] = value     Def __delitem__ (Self, key):         print (' del obj[key] , execute ')         self.__dict__.pop (key) Obj = foo (' Egon ') print ( Obj.name) #obj .name =  ' Alex ' #obj [' name '] =  ' Alex ' Print (obj[' name ']) del obj[' name '] Print (obj[' name ']) __call__To return the function, you can turn the object into a callable example: class foo:    def __call__ (Self, *args, **kwargs):         print (' ====> ') Obj = foo () obj () __getattr__ When you read a property from an object, you first need to search for the property from Self.__dicts__, and then find the property __setattr__ used to set the object from __getattr__, set the property through the __SETATTR__ function in object __ Delattr__ An example of an attribute used to delete an object: class foo:    def __init__ (self, x):         SELF.X = X    DEF __GETATTR__ (Self, item ):         print (' getattr ')     def __setattr__ (Self, key, value):        self.__dict__[key] =  value    def __delattr__ (Self, item):         self.__dict__.pop (item) Obj = foo (Obj.x = 1print) (obj.__dict__) Del obj.xprint ( obj.__dict__) OBJ.A =&NBsp;1obj.b = 2print (obj.__dict__) del obj.aprint (obj.__dict__) print ( The Obj.aaaaaaaaaexec function extracts the Python code from the string to execute an example: s= "Print (x)" g={' x ': 100000000}l={' x ': 1}exec (s,g,l) s =  "y=2 "EXEC (s, g, l) print (g) Print (L)

二、二次 Processing Standard Class

Example:

(): (itemtag=): ().        (item). Tag=tag (P_object): (p_object): (%p_object) (List). Append (P_object) (): Mid_index= ()//[mid_index] ():. Tag: () (). Clear (). Tag=l=list ([]) (L) (L.mid)

Example of implementing an iterator protocol: class foo:    def __init__ (Self, n, stop):         self.n = n        self.stop  = stop    def __next__ (self):         if self.n > self.stop:             raise StopIteration        x = self.n         self.n += 1         return x    def __iter__ (self):         return selfobj = foo (0, 5) print (Next (obj)) print (Next (obj)) print (Next (obj)) implements the context Manager: Example: class foo:    def __init__ (self, name):         self.name&nbSp;= name    def __enter__ (self):         print (' Enter ')         return self     def __exit__ (SELF,  EXC_TYPE, EXC_VAL, EXC_TB):         print (' exit ') With foo (' Alex ')  as x:    print (x)      print (' = = ')     print (' = = ')     print (' + ')

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The advanced object-oriented learning of Python learning