[python]locals内置函数

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.

Note: The contents of this dictionary should not be modified; changes may not affect the values of local and free variables used by the interpreter.

内置函数locals返回的是当前状态的本地命名空间, 应该当作只读字典处理, 写入会有意外发生.

在函数中, 或者其他局部变量产生的情况下, 对其的更改可能无法保存.

def f():
    x = 10
    lc = locals()
    lc['x'] = 20
    # 'x'->20 remains on dictionary before locals() is called
    print lc
    # {'x': 20}
    locals()
    # locals dictionary is refreshed in the above call to locals()
    print lc
    # {'x': 10, 'lc': {...}}     

f()