Python-based namespaces and scopes, function nesting

First, the name space

1, definition: storage of the name and value of the binding relationship

2. Namespaces are divided into: built-in namespaces, global namespaces, local namespaces

Built-in namespaces: The Python interpreter comes with its own name, and the Python interpreter starts to generate

Global namespaces: File-level-defined names are stored with the global namespace, which is generated when a Python file executes

Local namespaces: Define names inside functions, local namespaces only take effect when functions are called, and end of function calls are invalidated

3. Order of loading: Load order of the three: built-in namespaces--global namespace--local namespace

4. Order of values: Built-in namespace, global namespace, local namespace 7

## max=10#def func (): #x =1## max=20#print (max)###func ()#max=10##def func (): #x =1#max=20## Print (max)#func ()###print (max)### x=0#def f1 ():## x=1#def f2 ():## x=2#def f3 ():## x=3#print (x)#f3 ()#F2 ()##F1 ()

Second, scope

1. Scope:

Global scope: The name of the built-in namespace and the global namespace are global, can be referenced anywhere in the entire file, and are globally valid

Local scope: The name of the local namespace is local, and can only be referenced within the function, locally valid

#x=1#def foo ():#def f2 ():#print (x)#F2 ()#def Bar ():#print (x)##foo ()#Bar ()#def f1 ():#x=1#def f2 (): #f2 =value## x=2#print (x)#F2 ()#F1 ()x=1deffunc (): x=2defF1 ():Pass    #Print (dir (Globals () [' __builtins__ ']) #全局作用域name    #print (Locals ()) #局部作用域namefunc ()Print(Globals () isLocals ())

2, the action sequence is: local scope "" "" The global scope

Three, function nesting

1. Nested Definitions of functions

 def   F1 ():  def   F2 ():  def   F3 ():  print  ( " from f3  "  )  print  ("  from f2   " " F3 ()  print  ( " 
   
    from F1  
     " 
    ) F2 () 
     #   print (F1)  F1 () 
   

2. Nested calls to functions

def max2 (x, y     ): if x > y:        return  x     Else:        return y def max4 (a,b,c,d):    res1#    #  at    #  to    return Res3 Print (Max4 (11,23,-7,31))

Python-based namespaces and scopes, function nesting