Python-based decorator detailed

The adorner's syntax begins with @, followed by the name of the adorner function, and optional parameters.

Following the adorner declaration is the optional parameters of the decorated function and the decorated function, as follows:

@decorator (Dec_opt_args) def func (Func_args): ....

In fact, generally speaking, the adorner is actually a function, a function used to wrap the function, the adorner is called when the function declaration is completed, and the function declared after the call is replaced by a function that has been decorated by the adorner.

Such as:

def deco (func): ... return func@decodef foo (): print ' foo ' #-----------------------------------#等价如下: def deco (func ): ... return funcdef foo (): print ' foo ' foo = Deco (foo)

Here's an example:

def deco1 (func): print ' OK ' return func@deco1def foo (): print ' foo ' foo () #输出--------------#ok #foo#---------------- --

If you do not use adorners, you can do the following:

def deco1 (func): print ' OK ' return funcdef foo (): print ' foo ' print foo #<function foo at 0x00afe6f0& Gt;foo = Deco1 (foo) foo () #输出--------------#ok #foo#------------------

In contrast, it can be found that the use of adorners is so simple and flexible. Especially in enterprise-level development.

It is also possible to overlap multiple adorners:

def deco1 (func): print ' Deco1 ' return funcdef Deco2 (func): print ' Deco2 ' return func @deco1 @deco2def foo (): print ' foo ' foo () #输出如下:-----------#deco2 #deco1#foo#---------------------

is equivalent to:

@deco1 @deco2def foo (ARG):p the-----------and inferior effect----------foo = deco1 (Deco2 (foo ()))

Two, a parameter, no parameter of the adorner

The above examples are basically parameters, and no parameters are simpler.

1. No reference

@deco1 @deco2def foo (ARG):p the---------------------

Foo = Deco1 (Deco2 (foo ()))

2. Have a reference

@deco1 (deco_arg) @deco2def foo (ARG):p

---------------------

Foo = Deco1 (Deco_arg) (Deco2 (foo ()))

Returns an adorner with a function as a parameter

Third, use

1. Reference log

2. Increase timing logic to detect performance

3. Ability to add transactions to functions

Iv. examples

From time import ctime,sleepdef Deco (func): Def decoin (): print ' [%s]:%s called '% (CTime (), func.__name__) return func return decoin@decodef foo (): Passfoo () sleep (4) for I in Range (2): Sleep (1) foo () #输出如下:------ --#[fri Jul 10:45:04 2013]:foo called#[fri Jul 10:45:09 2013]:foo called#[fri Jul 10:45:10 2013]:foo called#----- -------------

Python-based decorator detailed