[Python-ideas] Short form for keyword arguments and dicts
Terry Reedy
tjreedy at udel.edu
Mon Jun 24 20:03:58 CEST 2013
On 6/24/2013 12:23 PM, Andrew McNabb wrote:
> Another use case where this would come in handy is with string
> formatting:
>
>>>> print('{spam} and {eggs}'.format(spam=spam, eggs=eggs))
>
> I've seen people use an awful workaround for this:
>
>>>> print('{spam} and {eggs}'.format(locals()))
That should be
print('{spam} and {eggs}'.format(**locals()))
Why do you see an intended usage as an 'awful workaround'?
If it is the inefficiency of unpacking and repacking a dict, that could
be fixed. One possibility is for ** to just pass the mapping when the
function only reads it, as is the case with .format (but how to know?).
A direct solution for .format is to add a keyword-only mapping
parameter:
print('{spam} and {eggs}'.format(map=locals()))
or mapping= names= or reps= (replacements) or strs= (strings) or dic= or
???=.
> While it looks a little magical, the proposed syntax would be an
> improvement (especially when there are many arguments):
>
>>>> print('{spam} and {eggs}'.format(=spam, =eggs))
It looks pretty hideous to me ;-).
And it still has repetition ;-).
--
Terry Jan Reedy
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