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Re: [Chicken-hackers] substring
From: |
Mario Domenech Goulart |
Subject: |
Re: [Chicken-hackers] substring |
Date: |
Fri, 26 Aug 2016 18:36:01 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.4 (gnu/linux) |
Hi,
On Fri, 26 Aug 2016 16:47:11 +0200 address@hidden wrote:
>> Out of curiosity: any example where substring=? would be useful in
>> practice?
>
> Grep the egg repo, you will find some uses.
As far as I can see, two out of 733 eggs use substring=? (readline and
pathfinder). A total of five calls.
All of them, except for a suspicious one in readline, require the use of
string-length. In one of the cases, string-length is applied twice on
the same input.
> But generally speaking, it's somewhat difficult to come up with a
> metric of usefulness - the danger being (as always) being blinded by
> our own limited experience.
Agreed.
I'm not proposing doing anything with substring=?. The discussion
came up when I wrongly used substring=? in my code and thought it was
a bug. After reading and reflecting on what the documentation says, I
understand that substring=? is not buggy (although I still think it is
a bit convoluted).
> Having a substring comparison is somwhat orthogonal to substring
> extraction and not having to allocate an intermediate string just to
> compare (say) two fields may save some bytes. Not necessarily in all
> implementations, but in a sufficiently smart one...
Agreed again.
All the best.
Mario
--
http://parenteses.org/mario