How to realize the decorator with Python

Editor to share with you how to achieve Python decorator, I believe that most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's go to understand it!

General decorator:

Go straight to the code.

Def demo (func_test): def wrapper (): print ('first decorator defined') func_test () print ('decorator end') return wrapper # be careful not to add parentheses @ demodef func_test (): print ('Xiaobai!!')

Directly use the original method of custom decorator enhancement.

Decorator with parameters:

Def demo (func_test): def wrapper (name): print ('the first decorator defined') func_test (name) print ('Oh, you are% s'% name) print ('decorator end') return wrapper@demodef func_test (name): print ('Hello, my name is% s'%name)

Don't you feel something?

Then there is the decorator without custom parameters.

Def demo (func_test): def wrapper (* name,**kwargs): print ('the first decorator defined') func_test (* name,**kwargs) print ('Oh You are% s ah'% name [0]) print ('you are% s'% name [1]) print ('decorator end') return wrapper@demodef func_test (name,age): print ('Hello, my name is% s'%name) print (' this year {} '.format (age))

Isn't that a simple answer? Ha ha ha ha

Multiple decorations are used together.

Def deco01 (func): def wrapper (* args,**kwargs): print ('layer 1 decorator') func (* args,**kwargs) print ('layer 1 decorator end') return wrapperdef deco02 (func): def wrapper (* args,**kwargs): print ('this is layer 2 decorator') print ('layer 2 decorator end') func (* args * * kwargs) return wrapper@deco02@deco01def func: print ('hello, here is a func') print ("result is% d"% (a+b+c)) print (' name: {} '.format (name))

If you look at the execution order, you can see that the decorator is executed from top to bottom.

Class decorator:

When using decorators, we can't write all the decorators and methods in the same file, we always have to separate them. This is about a class decorator.

Here, I probably wrote an example of reading a file decorator.

Class Mydecorator (): def _ _ init__ (self,func): # is defined as a private property self.func = func # implements the _ _ call__ method, making the object callable Callable objects can use def _ call__ (self, * args, * * kwargs) as functions: print ('test class decorator') self.func (* args) catalogue = args [0] suffix = catalogue.split ('.') [2] try: if suffix = 'json': with open (* args,'r') Encoding='utf-8') as file_object: contents = json.load (file_object) print (contents) else: with open (* args,'r' Encoding='utf-8') as file_object: contents = file_object.read () print (contents) except Exception as a: print ('error reading file pull: {}' .format (a) @ Mydecoratordef name (name): print ('Please enter the corresponding file path:% s'%name)

The above is all the contents of the article "how to implement the decorator in Python". Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!