The LEGB rule of python--scope

1 Scope of variables

　　Python is a static scope, meaning that in Python, the scope of a variable derives from its position in the code, and there may be different namespaces in different locations. Namespaces are the embodiment of variable scopes.

2 LEGB meaning of the respective representatives

　　2.1 l-local
　　　　namespace within the function. Scope: The current entire function body range.

　　2.2 e-enclosing Function locals
　　　　The namespace of the outer nested function. Scope: Closure function.

　　2.3 G-global
　　　　The global namespace. Scope: Current module (file).
　　2.4 B-builtin
　　　　Built-in module namespaces. Scope: All modules (Files).

Note: There is no block-level scope in Python. Block-level scope, a variable in a code block, such as the IF and for post code.

3 LEGB Rules
The LEGB rule is to look for variables in l->e->g->b order. In other words, when a variable with the same variable name is found in a different namespace, we first look for the local variable, and if it is not found, then look for the global variable.

4 common variable types based on namespaces

　　4.1 Local Variables

　　　　A variable that is defined inside a function. Scope is inside the function. View Local Variables command: Locals ().

　　4.2 Global Variables

　　　　Outside the function, variables defined at the outermost of the file. Scope is internal to the entire file. View Global Variables Command: Globals ()

　　4.3 note
　　　　Variable access principle: from inside to outside. When the names of global variables and local variables are identical, the nearest principle is adopted.

4 Case explanation

　　The 4.1 code is as follows

1A ="G Global"                         #defines a global variable A and assigns "G global" to a2 defmyfunc ():3A ="e Local 1"                    #A local variable A is defined, and the "E Local 1" is assigned to a4 5     definner ():6A ="L Partial 2"                #A local variable A is defined, and the "E Local 1" is assigned to a7          Print("Inner printed A:", a)8 Inner ()9     Print("MyFunc printed A:", a)Ten  One  A MyFunc () - Print("__main__ printed A:"A

4.2 Code Execution Results

　　　　

　　4.3 Code results analysis

　　　　

python--LEGB rules for scopes