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Python内置函数(39)——locals

时间:2016-11-04 23:20:45      阅读:332      评论:0      收藏:0      [点我收藏+]

 英文文档:

locals()

Update and return a dictionary representing the current local symbol table. Free variables are returned by locals() when it is called in function blocks, but not in class blocks.

 

说明:

  1. 函数功能返回当前作用域内的局部变量和其值组成的字典,与globals函数类似(返回全局变量)

>>> locals()
{__package__: None, __loader__: <class _frozen_importlib.BuiltinImporter>, __doc__: None, __name__: __main__, __builtins__: <module builtins (built-in)>, __spec__: None}

>>> a = 1

>>> locals() # 多了一个key为a值为1的项
{__package__: None, __loader__: <class _frozen_importlib.BuiltinImporter>, a: 1, __doc__: None, __name__: __main__, __builtins__: <module builtins (built-in)>, __spec__: None}

  2. 可用于函数内。

>>> def f():
    print(before define a )
    print(locals()) #作用域内无变量
    a = 1
    print(after define a)
    print(locals()) #作用域内有一个a变量,值为1

    
>>> f
<function f at 0x03D40588>
>>> f()
before define a 
{} 
after define a
{a: 1}

  3. 返回的字典集合不能修改。

>>> def f():
    print(before define a )
    print(locals()) # 作用域内无变量
    a = 1
    print(after define a)
    print(locals()) # 作用域内有一个a变量,值为1
    b = locals()
    print(b["a"]: ,b[a]) 
    b[a] = 2 # 修改b[‘a‘]值
    print(change locals value)
    print(b["a"]: ,b[a])
    print(a is ,a) # a的值未变

    
>>> f()
before define a 
{}
after define a
{a: 1}
b["a"]:  1
change locals value
b["a"]:  2
a is  1
>>> 

 

Python内置函数(39)——locals

原文:http://www.cnblogs.com/sesshoumaru/p/6031726.html

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