Re: Check for variable without leaving a trace

make your own solution:

use Data::Dumper;

print Dumper  \%hash;

print safe_defined(\%hash,"test","test2");

print Dumper  \%hash;


sub safe_defined
{
        my ($h,@keys) = @_;
        for(@keys)
        {
                return 0 unless defined $h->{$_};
                $h = $h->{$_};
        }
        return 1;
}
[download]

UPDATE: On a second thought, you should really use exists to test if a key exists on a hash, just change the defined keyword on the sub.

Comment on Re: Check for variable without leaving a trace Download Code

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Re^2: Check for variable without leaving a trace by educated_foo (Vicar) on Dec 09, 2009 at 14:47 UTC
This isn't what I'm trying to do. I want to check whether a program has used the variable `%hash` without creating it. You used to be able to do this with defined, but someone thought it would be a good idea to deprecate that. `exists $::{hash}` can tell you whether one or more of `$h, &h, %h, @h` is defined, but not which.	[reply] [d/l] [select]
Re^3: Check for variable without leaving a trace by Fox (Pilgrim) on Dec 09, 2009 at 16:03 UTC
hm, now I get it. but I think not even perl can tell that ( $h was used and %h was not, for example)	[reply]
Re^4: Check for variable without leaving a trace by educated_foo (Vicar) on Dec 09, 2009 at 16:34 UTC
It mostly can (or at least could before 5.11), using defined: `main @> $test = 1 1 main @> defined $test 1 main @> defined %test '' main @> %test2 = 1,2 1 2 main @> defined $test2 '' main @> defined %test2 1 main @> %test3 = () undef main @> defined %test3 '' main @> defined $test3 ''` [download] It doesn't detect an empty hash, but that's good enough for me.	[reply] [d/l]
Re^5: Check for variable without leaving a trace by Fox (Pilgrim) on Dec 09, 2009 at 17:07 UTC