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Shortcut for if(defined($var) && $var ne "") ? vikimun 04-06-2008
Posted by vikimun on April 6, 2008, 2:53 am
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 Is there shorter equivalent of if(defined($var) && $var ne "")
that doesn't fall for the "0" case, and doesn't produce warning with -
w ?

Thanks
V.M.

Posted by Johann Kappacher on April 6, 2008, 4:34 am
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 vikimun@gmail.com wrote:
> Is there shorter equivalent of if(defined($var) && $var ne "")
> that doesn't fall for the "0" case, and doesn't produce warning with -
> w ?
>
> Thanks
> V.M.
Hmm,

if (length $var) ....

--jk

Posted by Johann Kappacher on April 6, 2008, 4:41 am
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Sorry,

it will produce warnings if it is not initialized.
If you want to avoid warnings you must use defined().

perl 5.10 introduces the defined-or Operator.
=> This is your solution.

--jk

Posted by Johann Kappacher on April 6, 2008, 1:47 pm
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Johann Kappacher wrote:
> Sorry,
>
> it will produce warnings if it is not initialized.
> If you want to avoid warnings you must use defined().
>
> perl 5.10 introduces the defined-or Operator.
> => This is your solution.
>
> --jk

... but no, you need a defined-and operator!
I give up, this exercise is futile!

Posted by Chris Mattern on April 6, 2008, 12:50 pm
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> Is there shorter equivalent of if(defined($var) && $var ne "")
> that doesn't fall for the "0" case, and doesn't produce warning with -
> w ?
>
> Thanks
> V.M.

I tried this test program:

#!/usr/bin/perl

use warnings;
use strict;

my $var;

if (defined($var) && $var ne "") {
print "$var\n";
}

It didn't produce any warnings. When I put in "my $var = 0;",
it printed "0", just like it should. I don't understand
your question. If by "shorter" you mean getting rid of the
defined() test, then, no, you can't get rid of that. If you
aren't sure if $var is going to be defined, you have to test
for it before trying to use it.

--
Christopher Mattern

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