Function Closure

Generating conditions

1. The internal function is defined in the external function
2. The inner function refers to a variable in the outer function
3. An external function has a return value , And the return value is ： Inner function name

Define format

def  External function ():
	...
	a = ...
	def  Internal function ():
		...
		 call a...
	return  Internal function 

give an example

//  Definition 
def func(a, b):
	c = 10
	def inner_func():
		s = a + b + c
		print(s)
	return inner_func

//  call 
ifunc = func(3, 5)
ifunc()

effect

1. You can use peer scopes
2. Read internal variables of other elements
3. Extend scope

shortcoming

1. The scope is not so intuitive
2. . Closures refer to local variables of external functions , The local variables of the external function are not released in time , Variables will not be garbage collected , So there is a certain memory occupation problem , Memory consumption