in reply to Re^4: Using a sting with a variable name
in thread Using a sting with a variable name

Really? That's not what I get (nor expect): 
use 5.010;

@var = qw (a b c);
$var2 = undef;
$one = '$var';
$two = '$var2';

if (defined ${"${\substr $one, 1}"}) {
    say '$var exists';
}
else {
    say '$var does not exist';
}

__END__
$var does not exist

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Re^6: Using a sting with a variable name
by ikegami (Patriarch) on May 11, 2009 at 15:47 UTC
    You're still only checking whether the variable is defined or not. The data I gave was for after you made the change you said would check for existence.
[reply]
      You really think the answer will change after adding a test for defined $one? Last time I looked, '$var' is a defined value.
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        Sorry, I used the wrong var name. What I meant is that fixing the failing case below and will cause the third to fail. 

        uuse strict;
use warnings;
no strict 'vars';

use Test::More tests => 3;

sub var_exists {
   my ($var) = @_;
   return defined ${substr $var, 1};
}

{
   no warnings 'once';
   $var1 = 'a';
   $var2 = undef;
   @var3 = qw( a b c );
}

ok(var_exists('$var1'),  'var1');
ok(var_exists('$var2'),  'var2');
ok(!var_exists('$var3'), 'var3');

        [download]
        1..3
ok 1 - var1
not ok 2 - var2
#   Failed test 'var2'
#   at a.pl line 20.
ok 3 - var3
# Looks like you failed 1 test of 3.

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