From: "Andrej Borsenkow" <borsenkow.msk@sni.de>
To: "ZSH workers mailing list" <zsh-workers@sunsite.auc.dk>
Subject: Speed of ZSH
Date: Fri, 21 May 1999 12:11:59 +0400 [thread overview]
Message-ID: <001a01bea361$994a2140$21c9ca95@mow.siemens.ru> (raw)
I recently needed to do a quick prototyping, and selected zsh just for the
easy programming. The task was: I get a file with records of length 2040
characters and need to extract several (~100) fixed width fields and write
them out separated by tabs. I had a list of fields in the form n1-n2, so I
just vi'ed them :-) to get $line[n1,n2].
The problems I got were:
1. I found, that it is near to impossible to ``read'' line without breaking
it on IFS. ``read -k'' did not work :-( After some play I found, that
unsetting IFS helps - not very nice. How useful would it be to add a flag
that says "read entire line in scalar variable without splitting"?
2. It is impossible to ``print'' arguments separated by user defined string
(only NL or NUL). I had to make an array out of fields, and then print it
with explicit join:
fields=( $line[n1,n2] ...)
print ${(j/\t/)fields}
(Aside: how useful would it be to add flag to ``print'' to define
separator?)
After doing it I found, that ZSH needs several seconds for a file with 28
records! That is really too much for such a simple task. I suspect, the
reason is constant reallocation of memory when first array is created
(remember, it has about 100 elements) and then when it is joined.
If anybody interested, I could recompile with profiling.
I don't use zsh-mem mostly because I don't understand, what it actually is
:-)
/andrej
next reply other threads:[~1999-05-21 8:12 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-05-21 8:11 Andrej Borsenkow [this message]
1999-05-21 10:18 ` Bart Schaefer
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