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Unpacking Argument Lists of Defi

Unpacking Argument Lists of Defi

作者: 淌水希恩 | 来源:发表于2019-07-26 14:55 被阅读0次

    The reverse situation occurs when the arguments are already in a list or tuple but need to be unpacked for a function call requiring separate positional arguments. For instance, the built-in range() function expects separate start and stop arguments. If they are not available separately, write the function call with the * operator to unpack the arguments out of a list or tuple:

    >>> list(range(3,6))
    [3, 4, 5]
    >>> args=[3, 6]
    >>> list(range(*args))
    [3, 4, 5]
    

    In the same fashion, dictionaries can deliver keywood arguments with the ** operator:

    >>> def parrot(voltage, state='a stiff', action='voom'):
    ... print("-- This parrot wouldn't", action, end=' ')
    ... print("if you put", voltage, "volts through it.", end=' ')
    ... print("E's", state, "!")
    ...
    >>> d = {"voltage": "four million", "state": "bleedin' demised", "action": "VOOM"}
    >>> parrot(**d)
    -- This parrot wouldn't VOOM if you put four million volts through it. E's bleedin' demised !
    

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