On Wed, May 17, 2017 at 12:14:05PM -0400, Alex Walters wrote: > Fnmath.filter works great. To remind people what it does, it takes an > iterable of strings and a pattern and returns a list of the strings that > match the pattern. And that is wonderful > > However, I often need to filter *out* the items that match the pattern (to > ignore them). In every project that I need this I end up copying the > function out of the fnmatch library and adding 'not' to the test clause.
At the cost of a slight inefficiency, you could use the pure Python equivalent given in the docs: https://docs.python.org/3/library/fnmatch.html#fnmatch.filter fnmatch.filter(names, pattern) Return the subset of the list of names that match pattern. It is the same as [n for n in names if fnmatch(n, pattern)], but implemented more efficiently. So your filter_false is: [n for n in names if not fnmatch(n, pattern)] which avoids the need for the copy-and-paste anti-pattern. Otherwise, I would support: - filter_false - or a glob symbol to reverse the sense of the test, e.g. ~ or ! as the first character; but I dislike functions that take boolean arguments to change their behaviour. It's not a 100% hard and fast rule, but in general I prefer to avoid functions that take a constant bool argument: # rather than this: function(important_args, True) function(important_args, False) # use this: function(important_args) function_false(important_args) (although there may be exceptions). -- Steve _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
