>>>> template = 'I am %s, and he %s last %s.'
>>>> values = ('coding', "coded', 'week')
>>>> formatted = template % values
>>>> formatted
> 'I am coding, and he coded last week.'
>>>> deformat(formatted, template)
> ('coding', 'coded', 'week')
>
> expanded (for better visual):
>>>> deformat('I am coding, and he coded last week.', 'I am %s, and he %s last
>>>> %s.')
> ('coding', 'coded', 'week')
>
> It would return a tuple of strings, since it has no way of telling what
> the original type of each item was.
>
> Any input? I've looked through the documentation of the string module
> and re module, did a search of the documentation and a search of this
> group, and come up empty-handed.
Yes, in the trivial case you provide, it can be done fairly
easily using the re module:
>>> import re
>>> template = 'I am %s, and he %s last %s.'
>>> values = ('coding', 'coded', 'week')
>>> formatted = template % values
>>> unformat_re = re.escape(template).replace('%s', '(.*)')
>>> # unformat_re = unformat_re.replace('%i', '([0-9]+)')
>>> r = re.compile(unformat_re)
>>> r.match(formatted).groups()
('coding', 'coded', 'week')
Thing's get crazier when you have things like
>>> answer ='format values into a string'
>>> template = 'The formatting string %%s is used to %s' % answer
or
>>> template = 'The value is %0*.*f'
>>> values = (10, 4, 3.14159)
>>> formatted = template % values
>>> formated
'The value is 00003.1415'
or
>>> template = 'Dear %(name)s, Thank you for the %(gift)s. It
was very %(adj).' % {'name': 'Grandma', 'gift': 'sweater', 'adj':
'nice'}
Additionally, things go a little tangled when the replacement
values duplicate matters in the template. Should the unformatting
of "I am tired, and he didn't last last All Saint's Day" be
parsed as ('tired', "didn't last", "All Saint's Day") or
('tired', "didn't", "last All Saint's Day"). The /intent/ is
likely the former, but getting a computer to understand intent is
a non-trivial task ;)
Just a few early-morning thoughts...
-tkc
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