Python closure details

Closure is actually nothing complicated. In general, if an internal function references a variable in the external scope (but not in the global scope), the internal function is considered as a closure) the word "closure" is believed to be familiar to many students who have programming in mathematics, but sometimes it is difficult to understand it. First look at the definition:

A closure is an entity composed of a function and its associated reference environment. For example, there is a definition in reference resources: when implementing deep constraints, you need to create something that explicitly represents the reference environment and bind it with the relevant subroutine, bind

Is called a closure.

Closure is actually nothing complicated.

In general, if an internal function references a variable in the external scope (but not in the global scope), the internal function is considered as a closure ). It is just an "inner" function, referred to by a name (variable), and this name (variable) is a local variable for the function whose "outer" contains it.

Maybe you still don't understand what a closure is. it doesn't matter. after reading the following small example, you will surely understand it!

#! /Usr/bin/env python
# Coding = UTF-8
# Http://www.pythontab.com

# Define a function
Def plus (number ):

# Define another function in the function. In fact, the function in this function is considered as a closure.
Def plus_in (number_in ):
# Print the number_in variable here, so that you can know which variable is passed in.
Print str (number_in) + "\ r \ n"

Return number + number_in
# Actually, the returned result is the closure result.
Return plus_in


# Assign a value to the plus function. The value 20 indicates the number of the parameter.
V1 = plus (20)

Print v1 (100) # note that 100 actually gives the number_in parameter


Running result:

100

120

Note: 100 is printed by print str (number_in) + "\ r \ n ".