Function knowledge points

Function definition ： Encapsulate a specific function or code , When you need to use this function, you can call it directly

Parameters ： When a function is called , Pass some information to the function

Parameter classification ：

One . Shape parameter , At the time of function definition , You need to prepare some variables to receive information

1. Positional arguments , Declare variables one by one according to position

2. Default parameter , Give a default value when the function is declared , If the argument is not passed , The default value takes effect

3. Dynamic transfer parameters

        1.*args, Indicates the dynamic transfer of all position parameters

        2.**kwargs, It means to take over the dynamic parameters of all keywords

The order ： Location >*args> The default value is >**kwargs

Two 、 Actual parameters ： The information actually transmitted during electrophoresis

        1. Positional arguments , Pass parameters by position

        2. Key parameters , Pass parameters according to the name of the parameter

        3. Mixing parameters ：

                The order ： Put the position parameter in front , Key parameters after → Otherwise, the report will be wrong , The official setting is like this

                

Return value ： After function execution , Will give the caller a result , The result is the return value

About return：

        1. As long as the function executes return, The function immediately stops and returns the contents , Within the function return The subsequent code of will not be executed

        2. If the function does not return, At this time, the outside world takes over None

        3. If it's written return

                1. Only written. retuan, Data is not followed , At this time, it is still None → amount to break

                2.return value , At this time, the function has a return value , The outside world can take over a data → Most used

                3.return value 1, value 2, value 3....., At this time, the function has multiple return values , The outside world receives tuples

Knowledge points to master function ：

1. Nested function

2. Scope of variable

3. Closure

4. Decorator

# fn： A function ;inner,ret Just change the name 
def wrapper(fn):
    def inner(*args,**kwargs):
        ret = fn(*args,**kwargs)
        return ret
    return inner()

@wrapper
def func():
    pass

5. iterator

6. generator

“ We can only go forward ”

yield

g = (x for x in xx)

7. The derived type

8. Anonymous functions

9.python Built in functions