> So I created this last night:
>
> import collections
>
> class braces_fmt(str):
>
> def __mod__(self, stuff):
> if isinstance(stuff, tuple):
> return self.__class__(self.format(*stuff))
> elif isinstance(stuff, collections.Mapping):
> return self.__class__(self.format(**stuff))
> else:
> return self.__class__(self.format(stuff))
>
> The biggest issue is that ``"%s" % {'a': 42}`` substitutes the dict
> instead of throwing an error that str.format() would do with the code
> above. But what's nice about this is I think I can use this now w/ any
> library that expects % interpolation and it should basically work.
So there's no need to change modules like logging to explicitly provide support
for {}-formatting? What's not to like? ;-) Something like this perhaps should
have been added in at the same time as str.format went in.
> I don't think Paul's suggestion requires much more work to support
> string.Template, simply a subclass that implements __mod__
True.
> I guess my question is what's the point of the class if you are simply
> converting it before you pass it in to the logger? To be lazy about
> the formatting call? Otherwise you could simply call str.format() with
> your arguments before you pass the string into the logger and not have
> to wrap anything.
That's exactly the reason - to defer the formatting until it's needed.
Otherwise you can always format the string yourself,as you say, and pass it as
the single argument in the logging call - logging won't know or care if it was
passed in as a literal, or was computed by %-, {}-, $- or any other formatting
approach.
Regards,
Vinay Sajip
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