How values ​​are passed when Python closures are executed

This article mainly introduces the value transfer method when Python closure is executed. It analyzes the value transfer principle and implementation method of Python closure execution in the form of examples. The code contains more detailed comments for easy understanding. What is needed Friends can refer to

The example of this article analyzes the value transfer method when Python closure is executed. Sharing it with everyone for your reference, the details are as follows:

There are problems in the code and explanations of the problems.

#!/usr/bin/python
#coding: utf-8
# 判断一个人是否及格，如果满分150，则90及格，如果满分100，则60及格
# 开始的疑惑：当fun函数执行完以后，对应的val的值就应该消失，但是，
# 当下面代码再次调用f(60)的时候（这个f()函数就是fun_c()函数）
# 却能够打印出val的值？？？
def fun(val):
  'val是得到的分数'
  # 打印此时存储的val的地址
  print("%x" % id(val))
  def fun_c(passline):
    'passline是及格线'
    if val >= passline:
      print("通过")
    else:
      print("不及格")
  return fun_c
f = fun(89) # f就是fun_c函数
# 利用__closure__打印出fun_c()函数的属性，可以发现f中第一个元素的id值和val的id值地址相同
# 这说明如果引用了外部的变量(enclosing变量)的话，会将这个变量添加到函数属性中
# 当再次进行查找(即f(60))的时候，并不是到代码中去查找，而是到函数属性中去查找
# 也就是上面的fun_c的属性中有val的值，是一个元组，不能够改变
print(f.__closure__)
f(60)
f = fun(89)
f(90)

Run result:

12ee0b0
(<cell at 0x017B24B0: int object at 0x012EE0B0>,)
通过
12ee0b0
不及格

Function of closure:

1. Code encapsulation

2. Code reuse

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In-depth understanding of Python closure mechanism

Python closure Method to implement counter

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