1. Features of the decorator:
(1) As long as it is a decorator, the function will appear as a parameter, that is, def function B (function A)
(2) It must have the characteristics of closure, as follows, define a decorator
2. Use decorators
(1) The house function is below decorate, and house will act as the decorated function
(2) Pass the decorated function house as a parameter to the decorator decorate
(3) Even if you do not write the calling function house(), the bottom layer will silently execute the decorate function
(4) Assign the return value to house
(5) At this time, I call house(), which is actually to call wrapper()
The specific process: first pass house to func, that is, func = house, then call the code inside, load variable a, print, load the wrapper function, print again, and finally return to the wrapper function. We see that there is nothing to pick up the wrapper. But the bottom layer uses the function house with the same name to replace the wrapper function by default, see the red box below.
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3. Decorator with parameters
4. Universal decorator
Now if you want to pass one parameter, multiple parameters, or no parameters, the decorator can accept it. You need to use the previous variable parameters and unpacking. *args, **kwargs.
5. If it is a multi-layer decorator, decorate the nearest one first.
6. The decorator with parameters is three layers
The first layer: responsible for receiving the parameters of the decorator
The second layer: responsible for receiving functions
The third layer: responsible for receiving the parameters of the function
Calling house() is equivalent to calling wrapper()
7. Examples of payment login verification
