[Python-ideas] Complicate str methods
mistersheik at gmail.com
Wed Feb 7 16:53:25 EST 2018
On Saturday, February 3, 2018 at 8:10:38 PM UTC-5, Steven D'Aprano wrote:
> On Sun, Feb 04, 2018 at 10:54:53AM +1100, Chris Angelico wrote:
> > Picking up this one as an example, but this applies to all of them:
> > the transformation you're giving here is dangerously flawed. If there
> > are any regex special characters in the strings, this will either bomb
> > with an exception, or silently do the wrong thing. The correct way to
> > do it is (at least, I think it is):
> > re.match("|".join(map(re.escape, strings)), testme)
> > With that gotcha lurking in the wings, I think this should not be
> > cavalierly dismissed with "just 'import re' and be done with it".
> This is not Perl and "just use a regex" is not a close fit to the
> culture of Python.
> Regexes are a completely separate mini-language, and one which is the
> opposite of Pythonic. Instead of "executable pseudo-code", regexes are
> excessively terse and cryptic once you get past the simple examples.
> Doing anything complicated using regexes is painful.
> Even Larry Wall has criticised regex syntax for choosing poor defaults
> and information density. (Rarely used symbols get a single character,
> while frequently needed symbols are coded as multiple characters, so
> Perlish syntax has the worst of both worlds: too terse for casual users,
> too verbose for experts, hard to maintain for everyone.)
> Any serious programmer should have at least a passing familiarity with
> regexes. They are ubiquitous, and useful, especially as a common
> mini-language for user-specified searching.
> But I consider regexes to be the fall-back for when Python doesn't
> support the kind of string matching operation I need, not the primary
> solution. I would never write:
> re.match('start', text)
> re.search('spam', text)
> will do. I think this proposal to add more power to the string methods
> is worth some serious consideration.
Completely agree with the sentiment. I don't know about this proposal, but
complicated regular expressions are never a good solution even when they
are the best solution.
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