* Can I do without "eval" here?
@ 2006-03-14 9:03 Com MN PG P E B Consultant 3
2006-03-14 9:16 ` DervishD
0 siblings, 1 reply; 4+ messages in thread
From: Com MN PG P E B Consultant 3 @ 2006-03-14 9:03 UTC (permalink / raw)
To: zsh-users Mailinglist
Maybe just a matter of style, but here is a (simplified) version of a
problem which
I have solved, but where I am not satisfied with the solution ...
Assume I have a command CMD which can be called in the following ways:
CMD -x FILENAME
CMD -y 'this is some string with alphanumerics and spaces' FILENAME
I call this CMD from a skript MYSCRIPT. If the skript is called with 1
parameter, I use the second form and put the
parameter into the argument of my -y option. If MYSCRIPT is called
without parameters, I use the -x option.
For sake of simplicity, we can assume that the FILENAME is always
hardcoded. That is, if someone calls
MYSCRIPT without any arguments, i.e.
MYSCRIPT
it should execute
CMD -x foo
But if MYSCRIPT is called like this:
MYSCRIPT "bar baz"
it should execute
CMD -y 'bar baz' foo
Here is my solution (which I ask you to improve):
#!/bin/zsh
if [[ $# -eq 0 ]]
then
options=-x
else
options="-y '$1'"
fi
eval CMD $options foo
The 'eval' is necessary here, because if I write just
CMD $options foo
CMD would see for example -y 'bar baz' as first argument, and not just
-y.
What I don't like in this example, is the usage of eval. Although it is
harmless in this particular case,
the filename 'foo', which is hardcoded here, comes in as a parameter too
in my real application, and
this means that it undergoes one level of evaluation too, which would
yield wrong results when it contains,
say, a $ character.
Of course one might argued that when you are thinking of filenames with
$, you are doomed anyway, but
still I'm not a big fan of using 'eval' anyway, so I wonder whether this
can be done without eval
too....
Ronald
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Can I do without "eval" here?
2006-03-14 9:03 Can I do without "eval" here? Com MN PG P E B Consultant 3
@ 2006-03-14 9:16 ` DervishD
2006-03-14 9:22 ` Michal Politowski
0 siblings, 1 reply; 4+ messages in thread
From: DervishD @ 2006-03-14 9:16 UTC (permalink / raw)
To: Com MN PG P E B Consultant 3; +Cc: zsh-users Mailinglist
Hi Ronald :)
* Com MN PG P E B Consultant 3 <mn-pg-p-e-b-consultant-3.com@siemens.com> dixit:
> What I don't like in this example, is the usage of eval. Although
> it is harmless in this particular case, the filename 'foo', which
> is hardcoded here, comes in as a parameter too in my real
> application, and this means that it undergoes one level of
> evaluation too, which would yield wrong results when it contains,
> say, a $ character.
Try this:
eval whatevercommand \''$file'\'
As for doing the same without eval, it can be done, too, by
setting the sh_word_split option and tweaking, or simply with this:
options=("-x")
(($#)) && options=("-y" "$1")
CMD $options[1] $options[2] foo
If "foo" comes from a parameter, just use that parameter instead
of "foo".
I haven't tested the solution, so it may need some refinement,
but it should do.
Raúl Núñez de Arenas Coronado
--
Linux Registered User 88736 | http://www.dervishd.net
http://www.pleyades.net & http://www.gotesdelluna.net
It's my PC and I'll cry if I want to... RAmen!
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Can I do without "eval" here?
2006-03-14 9:16 ` DervishD
@ 2006-03-14 9:22 ` Michal Politowski
2006-03-14 9:42 ` DervishD
0 siblings, 1 reply; 4+ messages in thread
From: Michal Politowski @ 2006-03-14 9:22 UTC (permalink / raw)
To: zsh-users Mailinglist
On Tue, 14 Mar 2006 10:16:19 +0100, DervishD wrote:
[...]
> options=("-x")
> (($#)) && options=("-y" "$1")
> CMD $options[1] $options[2] foo
There is no need to split the array manually.
CMD $options foo
will do.
--
Michał Politowski
Talking has been known to lead to communication if practiced carelessly.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2006-03-14 9:41 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2006-03-14 9:03 Can I do without "eval" here? Com MN PG P E B Consultant 3
2006-03-14 9:16 ` DervishD
2006-03-14 9:22 ` Michal Politowski
2006-03-14 9:42 ` DervishD
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