in reply to Re^5: Using a sting with a variable name
in thread Using a sting with a variable name

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.
  • Comment on Re^6: Using a sting with a variable name

Replies are listed 'Best First'.
Re^7: Using a sting with a variable name
by JavaFan (Canon) on May 11, 2009 at 16:36 UTC
    You really think the answer will change after adding a test for defined $one? Last time I looked, '$var' is a defined value.
[reply]
[d/l]
[select]

      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.

      [download]
[reply]
[d/l]
[select]
        From a Perl (language!) point of view, there's no difference between a package variable that hasn't been used, and a package variable which is undefined. The following, after all, is a valid Perl program; it compiles and runs: 
           print $foo;

        [download]
        it may warn, but it's valid.

        It only matters in the implementation, and in the few edge cases where you can poke into the underlaying implementation.

[reply]
[d/l]

In Section Seekers of Perl Wisdom