Complement 8.python Face Object Part.7 (supplementary to class-related functions)

One, Isinstance (OBJ.CLS) & Issubclass (Sub,super)

1. Isinstance (OBJ.CLS): Used to check whether an object belongs to a class. (Whether an object is generated by a class)

L1 = List ()

Print Isinstance (l1,list)

Output:

True

2.issubclass (Sub,super): Used to determine whether a class is a subclass of another class.

#sub refers to subclasses, and Super refers to the parent class.

Class C1 (object):

Pass

Class C2 (C1):

Pass

Print Issubclass (C2,C1)

Output:

True

Two, __getattribute__ (built-in method)

This built-in approach, which is similar in name to __getattr__, but the conditions for triggering this built-in method are completely different from the __getattr__!

In an object, __getattr__ is triggered when the property or method you are looking for cannot be found.

__GETATTRBUTE__ will trigger this method regardless of whether the method or property can be found! Once this method is executed, if a Attributeerror exception is not triggered internally, then the __getattr__ method will never be triggered.

Here is an example:

class Class1 (object):

def __init__ (self,x):

self.x = X

def __getattr__ (self, item):

Print "Call __getattr__"

Obj1 = Class1 (123)

Print obj1.x

Output:

Call Test

# then call a non-existent property

obj1.asadsdsadasfasf

Output:

The call __getattr__ #__getattr__ method was successfully executed.

class Class1 (object):

def __init__ (self,x):

self.x = X

def __getattr__ (self, item):

Print "Call __getattr__"

def __getattribute__ (self, item):

Print "Call __getattribute__"

Raise Attributeerror ("^-^") # Throws a Attributeerror

Obj1 = Class1 (123)

obj1.x

Obj1.asasasasasas

Output execution Result:

Call __getattribute__

Call __getattr__

Call __getattribute__

Call __getattr__

From the above results, __getattribute__ when thrown a Attributeerror exception, __getattr__ will be triggered!!

This article is from the "Rebirth" blog, make sure to keep this source http://suhaozhi.blog.51cto.com/7272298/1917990

Complement 8.python Face Object Part.7 (supplementary to class-related functions)