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From: Janis Papanagnou <janis_papanagnou+ng@hotmail.com>
Newsgroups: comp.unix.shell,comp.unix.programmer,comp.lang.misc
Subject: Re: Command Languages Versus Programming Languages
Date: Fri, 22 Nov 2024 12:14:32 +0100
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On 20.11.2024 18:50, Rainer Weikusat wrote:
> Janis Papanagnou <janis_papanagnou+ng@hotmail.com> writes:
> 
>> Personally I think that writing bulky procedural stuff for something
>> like [0-9]+ can only be much worse, and that further abbreviations
>> like \d+ are the better direction to go if targeting a good interface.
>> YMMV.
> 
> Assuming that p is a pointer to the current position in a string, e is a
> pointer to the end of it (ie, point just past the last byte) and -
> that's important - both are pointers to unsigned quantities, the 'bulky'
> C equivalent of [0-9]+ is
> 
> while (p < e && *p - '0' < 10) ++p;
> 
> That's not too bad. And it's really a hell lot faster than a
> general-purpose automaton programmed to recognize the same pattern
> (which might not matter most of the time, but sometimes, it does).

Okay, I see where you're coming from (and especially in that simple
case).

Personally (and YMMV), even here in this simple case I think that
using pointers is not better but worse - and anyway isn't [in this
form] available in most languages; in other cases (and languages)
such constructs get yet more clumsy, and for my not very complex
example - /[0-9]+(ABC)?x*foo/ - even a "catastrophe" concerning
readability, error-proneness, and maintainability.

If that is what the other poster meant I'm fine with your answer;
there's no need to even consider abandoning regular expressions
in favor of explicitly codified parsing.

Janis

PS: And thanks for answering on behalf of the other poster whom I
see in his followups just continuing his very personal style.