Python high-order 3 python Adorner

Knowledge Content:

1. Decorator Introduction

2. Open Closure principle

3. Fixed structure of the adorner

4. Decorative Adorner with parameters

5. Multiple adorners decorate a function

First, the introduction of the decorative device

1. Definition of adorners

Definition: An adorner or a function in essence, but it is intended to decorate other functions, that is, to add some functionality.

2. Function and nature of the adorner

Function: Extend the function of the original function without modifying the original function and its calling mode

Essence: It is a function, it can be said to be a closure function

3. Principles of adorners

(1) cannot modify the source code of the decorated function

(2) cannot modify the calling mode of the decorated function

The above two points plainly, even if the adorner is the function of the decoration is transparent, that is, the function of decoration is not aware of the existence of decorative functions,

The decorated function is the same as the original.

4. A simple decorator

1 #the adorner that counts the run time of the program:2 Import Time3 4 defTimmer (func):5     defWarpper (*args, * *Kwargs):6Start_time =time.time ()7 func ()8Stop_time =time.time ()9         Print("The func run time is%s"% (stop_time-start_time))Ten     returnWarpper One  A @timmer - deftest1 (): -Time.sleep (3) the     Print("In the test1") -  -  -Test1 ()

5. Knowledge needed to implement adorners

Realize the Knowledge reserve of adorners:

(1) function is "variable"

(2) Higher order functions

(3) Nested functions

High-order functions + nested functions, adorners

For more information on the above can be seen in my other blog, specific location: click here

Ii. the principle of open closure

The open closure principle is an important concept in the development, the main contents are as follows:

• is open to the extension
• The modification is closed.

Of course, the use of adorners in Python development is a good way to implement this principle, because adorners can extend the function of the original function without modifying the original function and its calling method.

Three, the fixed structure of the adorner

Four, with parameters of the adorner

Five or more adorners decorate a function

Python high-order 3 python Adorner