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feature request: a better str.endswith

John Machin sjmachin at lexicon.net
Fri Jul 18 20:02:28 EDT 2003 
mis6 at pitt.edu (Michele Simionato) wrote in message news:<2259b0e2.0307180401.5dae02f2 at posting.google.com>...
> I often feel the need to extend  the string method ".endswith" to tuple
> arguments, in such a way to automatically check for multiple endings.
> For instance, here is a typical use case:
> 
> if filename.endswith(('.jpg','.jpeg','.gif','.png')):
>     print "This is a valid image file"
> 
> Currently this is not valid Python and I must use the ugly
> 
> if filename.endswith('.jpg') or filename.endswith('.jpeg') \
>    or filename.endswith('.gif') or filename.endswith('.png'):
>     print "This is a valid image file"
> 

alternative 1:

>>> import re
>>> has_image_file_extn =
re.compile(r".*[.](jpg|jpeg|png|gif)$").match
>>> has_image_file_extn('foo.jpg')
<_sre.SRE_Match object at 0x00769F30>
>>> has_image_file_extn('foo.txt')
>>>

The above has factored out the common "." but is otherwise general for
any list of suffixes.

alternative 2:

>>> has_image_file_extn = lambda f: f.split('.')[-1] in
['jpg','jpeg','png','gif']
>>> has_image_file_extn('foo.jpg')
1
>>> has_image_file_extn('foo.txt')
0
>>>

This is of course restricted to cases where you can isolate the suffix
lexically. If the list is long and/or used frequently, then it might
be better to use a built-at-module-start-up dictionary instead.
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