Python內建函數locals

英文文檔：

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.

說明：

　　1. 函數功能返回當前範圍內的局部變數和其值組成的字典，與globals函數類似(返回全域變數)

>>> locals(){'__package__': None, '__loader__': , '__doc__': None, '__name__': '__main__', '__builtins__': , '__spec__': None}>>> a = 1>>> locals() # 多了一個key為a值為1的項{'__package__': None, '__loader__': , 'a': 1, '__doc__': None, '__name__': '__main__', '__builtins__': , '__spec__': None}

　　2. 可用於函數內。

>>> def f():    print('before define a ')    print(locals()) #範圍內無變數    a = 1    print('after define a')    print(locals()) #範圍內有一個a變數，值為1    >>> f>>> 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()) # 範圍內無變數    a = 1    print('after define a')    print(locals()) # 範圍內有一個a變數，值為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的值未變    >>> f()before define a {}after define a{'a': 1}b["a"]:  1change locals valueb["a"]:  2a is  1>>>

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