Regular expressions

[Steven D'Aprano]

On Thu, 5 Nov 2015 11:13 am, rurpy at yahoo.com wrote:

> There would be far fewer computer languages, and they would be much
> more primitive if regular expressions (and the fundamental concepts
> that they express) did not exist.

Well, that's certainly true. But only because contra-factual statements can
imply the truth of anything. If squares had seven sides, then Joseph Stalin
would have been the first woman to go to the moon on horseback.

I can't imagine a world where pattern matching doesn't exist. That's like
trying to imagine a world where arithmetic doesn't exist. But I think we
can safely say that, had nobody thought of the idea of searching for
patterns ('find me all the lines with "green" in them'), there would be far
fewer regex libraries in existence. I doubt that there would be "far fewer"
programming languages. With the possible exception of Perl, sed and awk,
I'm not aware of any languages which were specifically inspired by, and
exist primarily to apply, regular expressions, nor any languages which
*require* regexes in their implementation. Most languages are built on
parsers, not regular expressions.


> But I really wish every mention of regexes here wasn't reflexively 
> greeted with a barrage of negative comments and that lame "two problems"
> quote, especially without an answer to the poster's regex question.

I don't disagree with this. Certainly we should accept questions from people
who are simply trying to learn how to use regexes without bombarding them
with admonitions to do something different. Yes yes, I know that regexes
aren't the only tool in my tool box, but *right now* I want to learn how to
use regexes.



-- 
Steven