Python Basic Learning----Decorator

The decorator can add some extra functions before and after the target function execution without modifying the target function code.

For example, there is a simple function

Import time

Def func1 ():
    Print ("This is a simple function")
    Time.sleep (2)

To add a calculation time function to this function, you can use the decorator

Let the function use a decorator, that is, add the @ function name above the definition of the function, as below, which is equivalent to writing func1=outer (FUNC1) to the program behind it

The reason why a parameter outside the function is used in a function is a closed packet

Import time
def outer (f):    def inner ():        start = Time.time ()        f ()        end = Time.time ()        print (End-start)    return Inner@outer#func1=outer (FUNC1) def func1 ():    print ("This is a simple function")    Time.sleep (2) func1 ()
#输出
This is a simple function.

2.000551223754883

If a function with parameters needs to be modified,

def outer (f):    def inner (x, y):        start = Time.time ()        f (x, y)        end = Time.time ()        print (End-start)    Return Inner@outer#func1=outer (FUNC1) def add (x, y):    print (x+y)    Time.sleep (2) Add

If you want to add some other statements in the decorator, such as a judgment statement, to control whether certain features are used

Import timedef judge (Flag=true):    def outer (f):        def inner (x, y):            start = Time.time ()            f (x, y)            end = Time.time ()            print (End-start)        return inner    if flag==true:        print ("This is a feature")    return Outer@judge () #judge () is actually equivalent to outer, except that you can add the parameter def add (x, y):    print (x+y)    Time.sleep (2) Add

　　

Python Basic Learning----Decorator