use module with parameter variable

QM has asked for the wisdom of the Perl Monks concerning the following question:

Just thought I'd share this gotcha I encountered while trying to use Getopt::Declare. [This is not specific to G::D, but occurs with any module taking variable parameters.]

#!/your/perl/here
use strict;
use warnings;

my $options;
my $string;

BEGIN 
{
    $string = <<'HERE';

    -one <one:i>    First parameter
    
HERE
}

use Getopt::Declare $string => $options;   ### <<< BONK!

print "one = $options->{-one}\n";
[download]

To use this form of G::D, $string and $options must exist (such as with my), and $string must be defined, such as through a BEGIN (before the compiler sees use Getopt::Declare).

To avoid this, at least with G::D, use the following instead:

use Getopt::Declare;
$options = Getopt::Declare->new($string);
[download]

You can use a banana to drive a nail, but you'll need to precondition the nail, or the banana, or both.

-QM
--
Quantum Mechanics: The dreams stuff is made of

Comment on use module with parameter variable Select or Download Code

Replies are listed 'Best First'.
Re: use module with parameter variable by revdiablo (Prior) on Aug 19, 2004 at 16:53 UTC
Another alternative is to use require instead of use: `BEGIN { require Getopt::Declare; import Getopt::Declare $string => $options; }` [download]	[reply] [d/l]
Re^2: use module with parameter variable by QM (Parson) on Aug 19, 2004 at 21:49 UTC
I must be missing the point: `BEGIN { require Getopt::Declare; import Getopt::Declare $string => $options; }` [download] This implies that `$string` is defined in an earlier `BEGIN`, doesn't it? -QM -- Quantum Mechanics: The dreams stuff is made of	[reply] [d/l] [select]
Re^3: use module with parameter variable by revdiablo (Prior) on Aug 19, 2004 at 21:57 UTC
`$string` could be defined inside the `BEGIN` block, or the `BEGIN` block could be left out altogether. I only included it in my example out of sheer reflex. :-) Here's another example that might be more useful: `my $options; my $string = <<'HERE'; -one <one:i> First parameter HERE require Getopt::Declare; import Getopt::Declare $string => $options;` [download]	[reply] [d/l] [select]