Hello LloydRice,

What you are trying to do is quite possible:

use strict;
use warnings;

#my $scale  = 42;
my $myscale = init_myscale(1);

print "\$myscale = >$myscale<\n";

sub init_myscale
{
    my ($default) = @_;

    no strict   qw( vars );
    no warnings qw( uninitialized );

    return eval $scale ? $scale : $default;
}
[download]

Output:

23:16 >perl 2018_SoPW.pl
$myscale = >1<

23:18 >
[download]

But, as haukex and LanX have said, the fact that you want to do this strongly suggests that there is a flaw in your design.

Update: return eval $scale ? $scale : $default; should be return eval defined $scale ? $scale : $default; to catch the case where $scale exists but has a false value ($state = 0). Note that this approach can’t be used to catch the case where $state exists but has the value of undef.

Hope that helps,