Python Notes-Decorator supplement

This essay is a supplement to Python's notes-adorners.

When using adorners, some properties of the decorated function are lost, such as the following code:

1 #!/usr/bin/env python2 3 defDeco (func):4     defwrapper ():5         Print "Wrap Start"6 func ()7         Print "Wrap end\n"8     returnwrapper9 Ten @deco One deffoo (): A     """docstring for Foo""" -     Print "In foo ():" -  the foo () - PrintFoo.__name__ - PrintFoo.__doc__

The output is as follows:

$ python decorator_test.pywrap startin foo (): Wrap Endwrappernone

It can be found that the __name__ property is wrapper, and the __doc__ attribute is none. This can be inconvenient for the usual use, and it is not always possible to rewrite __name__ and __doc__ for each function that uses adorners.

Python's Functools provides update_wrapper and wraps that can solve this problem effectively. However, Update_wrapper is called in the form of a method, while wraps encapsulates the update_wrapper with an adorner. The sample code is as follows:

1 #!/usr/bin/env python2  fromFunctoolsImportUpdate_wrapper3 4 defDeco (func):5     defwrapper ():6         Print "Wrap Start"7 func ()8         Print "Wrap end\n"9     returnUpdate_wrapper (Wrapper,func)#calling the Update_wrapper methodTen  One @deco A deffoo (): -     """docstring for Foo""" -     Print "In foo ():" the  - foo () - PrintFoo.__name__ - PrintFoo.__doc__

1 #!/usr/bin/env python2  fromFunctoolsImportWraps3 4 defDeco (func):5@wraps (func)#using adorners to implement6     defwrapper ():7         Print "Wrap Start"8 func ()9         Print "Wrap end\n"Ten     returnwrapper One  A @deco - deffoo (): -     """docstring for Foo""" the     Print "In foo ():" -  - foo () - PrintFoo.__name__ + PrintFoo.__doc__

The Foo method, now decorated by Deco, preserves the previous __name__ and __doc__ properties.

for for Foo 

Python Notes-Decorator supplement