Python function scope

function scopes in Python

In Python, a function is a scope

=‘xiaoyafei‘def change_name():    =‘肖亚飞‘    print(‘在change_name里的name:‘,name)change_name()  # 调用函数print("在外面的name:",name)

The results of the operation are as follows:

在change_name里的name: 肖亚飞在外面的name: xiaoyafei

Let's try again how is it found in nested functions?

=15def func():    print(‘第一层age:‘,age)  # 第一层age: 15    def func2():        =73        print("func2中的age:",age)  # func2中的age: 73        def func3():            =84            print("func3中的age:",age)  # func3中的age: 84        func3()  # 调用func3函数    func2()  # 调用func2函数func()

In the above nested function, it is well explained that a function is a scope, then we can now change the code a little bit to see the situation?

=15def func():    print(‘第一层age:‘,age)  # 第一层age: 15    def func2():        print("func2中的age:",age)  # func2中的age: 15  # 看到没有,如果当前作用域里没有age变量,那么它就会往上找        def func3():            =84            print("func3中的age:",age)  # func3中的age: 84        func3()  # 调用func3函数    func2()  # 调用func2函数func()

Well, then, when someone says, "a whole bunch of crap is about local variables and global variables, then I want to ask: in this nested function, there is no age variable in Func2, so how does it find the global variable, age = 15?"

Now we need to look at the scope lookup order:

Variable Scope LEGB

• namespaces within the L:locals function, including local variables and arguments
• E:enclosing the namespace of the outer nested function, that is, adjacent to the previous layer, for example, said: FUNC2 No age variable will go to the Func find this
• G:globals Global Variables
• B:builtins the namespace of the built-in module

Cough, or first understand what is the name space?

namespace, aka name space , as the name implies is the place to store names, what name? for example, x = 1, 1 is stored in memory, so where is the variable name x stored? Namespaces are places where names X and 1 bind.

>>>=1>>>id(1)1576430608

The namespace is divided into the following 3 types:

• Locals: is a namespace within a function, including local variables and formal parameters
• GLOBALS: global variable, the namespace of the module in which the function is defined
• Builtins: Namespaces for built-in modules

Different scopes of variables are determined by the namespace in which the variable resides.

Scope is range

• Global scope: Global survival, globally valid
• Local scope: Temporary inventory, partially valid

Let's take an example to see

Level= ' L0 'N=  AdefFunc (): Level= ' L1 'N=  -    Print(Locals())# {' n ':, ' Level ': ' L1 '}    defOuter (): N=  -Level= ' L2 '        Print(Locals(), N)# {' Level ': ' L2 ', ' n ': +}        defInner (): level= ' L3 '            Print(Locals(), N)# {' Level ': ' L3 ', ' n ': +}Inner () outer () func ()

With the rules of L-E-G-->b, that is: in the local can not find, will go to local outside the local search (such as closures), and can not find the global find, and then go to the built-in function to find.

Python function scope