Python Forum

is there a way to handle function/method keyword aliasing other than using **kwargs and coding the logic to handle it? for example i might have position= for a defined function/method but also want to allow pos= to be the same thing. what about multiple aliases? what if the caller uses more than one of them?

    putfoo(bar,position=5,pos=3)

You can do anything in python, but this is really not pythonic

def putfoo(bar, position=None, pos=None):
    pos = merge_aliases(None, position=position, pos=pos)
    print('Position is:', repr(pos))

class TooManyParameters(RuntimeError):
    pass
    
def merge_aliases(default, **kwargs):
    d = {k: v for k, v in kwargs.items() if v is not default}
    if d:
        if len(d) > 1:
            raise TooManyParameters(
                'Only one of the following parameters can be set:',
                list(d.keys()))
        else:
            return d.popitem()[1]
    else:
        return default
    
if __name__ == '__main__':
    putfoo('hello', position=7)
    putfoo('hello', pos=9)
    putfoo('hello', position= 11, pos=13)

Output:
Position is: 7
Position is: 9
Traceback (most recent call last):
  File "paillasse/multiargs.py", line 24, in <module>
    putfoo('hello', position= 11, pos=13)
  File "paillasse/multiargs.py", line 3, in putfoo
    pos = merge_aliases(None, position=position, pos=pos)
  File "paillasse/multiargs.py", line 15, in merge_aliases
    list(d.keys()))
__main__.TooManyParameters: ('Only one of the following parameters can be set:', ['pos', 'position'])