Path: csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail
From: Chris Angelico <rosuav@gmail.com>
Newsgroups: comp.lang.python
Subject: Re: String format - resolve placeholders names
Date: Sat, 21 Nov 2015 02:06:11 +1100
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On Sat, Nov 21, 2015 at 1:52 AM, Ervin Heged=C3=BCs <airween@gmail.com> wro=
te:
> Python has a good string formatter, eg. I can do this:
>
> s =3D "{who} likes {what}"
> d =3D {'who': "Adam", 'what': "ants"}
> s.format(**d)
>
> result:
> 'Adam likes ants'
>
> Is it possible, and if yes, how to resolve the placeholders names
> in string?
>
> There is a know method:
>
> d1 =3D {'who1': "Adam", 'what1': "ants"}
> try:
>     s.format(**d1)
> except KeyError:
>     print("keyword missing")
>
> (gives 'keyword missing' as result).
>
>
> But is there any other (direct) way, which keywords exists in
> string?

I think what you're asking for can be done using format_map with a
custom mapping object:

>>> class IdentiMap:
...     def __init__(self):
...         self.keys =3D []
...     def __getitem__(self, key):
...         self.keys.append(key)
...
>>> m =3D IdentiMap()
>>> "{who} likes {what}".format_map(m)
'None likes None'
>>> m.keys
['who', 'what']

Does that help?

ChrisA