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[Python-ideas] Fix the DRY problem (was Re: PEP 501

[Python-ideas] Fix the DRY problem (was Re: PEP 501 - i18n with marked strings)

Eric Fahlgren ericfahlgren at gmail.com
Tue Aug 11 22:32:03 CEST 2015 
From: Barry Warsaw [mailto:barry at python.org]
> But the DRY argument is much more compelling to me, and currently I think the
> best way to reduce repetition in function arguments is through sys._getframe()
> and other such nasty tricks.  I'd really much prefer to see this small annoyance
> fixed in a targeted way than add a hugely complicated new feature that reduces
> readability (IMHO).
> 
> Which is why I like the scope() and similar ideas.  Something like a built-in that

This +100.  I've been doing my own variants on the f-string for over a decade and
every time I type "sys.__getframe()" I think to myself, "There's got to be a better way..."

Here's a stripped-down example from Real Life (gah!):

>>>     def formatSolverFunction(self, s, **kwds):
>>>         localFrame = sys._getframe().f_back
>>>         localDict  = localFrame.f_locals
>>>         localDict.update(kwds)                  # Our **kwds override locals.
>>>         globalDict = localFrame.f_globals
>>> 
>>>         #-----------------------------------------------------------------------
>>>         def sub(match):
>>>             fmt = match.groups()[0].split(":", 1)
>>>             val = eval(fmt[0], globalDict, localDict)
>>> 
>>>             if isinstance(val, SimulatableObject):
>>>                 val = val.id
>>> 
>>>             if len(fmt) > 1:
>>>                 try:
>>>                     val = val.__format__(fmt[1])
>>>                 except ValueError as e:
>>>                     ... error reporting ...
>>>             return str(val)
>>> 
>>>         while True:
>>>             s, n = re.subn(r"{([\w.:]*)}", sub, s) # We don't support !s or !r.
>>>             if n == 0: break
>>>         return s
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