[Python-ideas] Make fnmatch.filter accept a tuple of patterns

[Stephen J. Turnbull]

Chris Angelico writes:
 > On Sat, Nov 3, 2018 at 4:49 AM Stephen J. Turnbull
 > <turnbull.stephen.fw at u.tsukuba.ac.jp> wrote:
 > > Andre Delfino writes:

 > >  > Frequently, while globbing, one needs to work with multiple
 > >  > extensions. I’d like to propose for fnmatch.filter to handle a
 > >  > tuple of patterns (while preserving the single str argument
 > >  > functionality, alas str.endswith),

 > > This is one of those famous 3-line functions, though:
 > >
 > >     import fnmatch
 > >     def multifilter(names, *patterns):
 > >         result = []
 > >         for p in patterns:
 > >             result.extend(fnmatch.filter(names, p))
 > >         return result
 > >
 > > It's a 3-line function in 5 lines, OK, but still.

 > And like many "hey it's this easy" demonstrations, that isn't quite
 > identical, as a single file can match multiple patterns

Sure.  I would have written it with set.union() on general principles
except I forgot how to say "union", didn't feel like looking it up,
and wanted to keep the def as close to 3 lines as I could without
being obfuscated (see below).  I wonder how many people would fall
into the trap I did.  (I don't consider myself a great programmer, but
maybe that's all the more reason for this?  Not-so-great minds think
alike? :-)

I was really more interested in the second question, though.  Why
invent yet another interface when we already have one that is
well-known and more powerful?

P.S.   I can't resist.  This is horrible, but:

def multifilter(names, *patterns):
    return list(set().union(*[fnmatch.filter(names, p) for p in patterns]))

Who even needs a function? ;-)