Getopt::Declare parameter variables

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

I'm using Getopt::Declare, but I also want to validate parameter values against each other, as in the following:

#!/your/perl/here

use strict;
use warnings;
use Getopt::Declare;
our $options;
 
$options = Getopt::Declare->new( <<'OPTIONS' );
  -one <one:i>    First parameter
  { defer
    { reject ( $one > $two 
        => '\$one ($one) > \$two ($two)' )
    }
  }

  -two <two:i>    Second parameter
  { defer
    { reject ( $one > $two 
        => '\$one ($one) > \$two ($two)' )
    }
  }
OPTIONS

print "one = $options->{-one}\n";
print "two = $options->{-two}\n";

__INVOKED_WITH__
perl declare.pl -one 10 -two 20

__OUTPUT__
Error: in generated parser code:
Global symbol "$two" requires explicit package name at (eval 7) line 1
+00.
Global symbol "$one" requires explicit package name at (eval 7) line 1
+44.
[download]

[Note that I've modified Declare.pm to capture the eval string in a variable before the eval, for debugging.]

The problem is that in the reject block $one is created as a my variable inside an eval string. So $two doesn't exist. And vice versa.

Is it possible to do this with Getopt::Declare?

Also, what about default values? I would prefer to preload default values, then have the reject block execute on the final result. However, the returned object doesn't exist to preload before Getopt::Declare->new().

One method is to define a validate sub in main that's called when each parameter is seen, to save the value, and do validation if possible. However, if I'm going to do that, I might as well just do this:

sub validate
{
    my $options = shift;
    $options->{-one} = 1 unless ( exists( $options->{-one} ) );
    $options->{-two} = 2 unless ( exists( $options->{-two} ) );
    
    die "Error: -one ($options->{-one}) > -two ($options->{-two}), "
      if ( $options->{-one} > $options->{-two} );
}
$options = Getopt::Declare->new( <<'OPTIONS' );
...
OPTIONS
validate( $options );
[download]

I was wondering if I was missing this functionality in Getopt::Declare. And if it's not there, what would it take to extend Getopt::Declare to take default values and an appropriate post-processing block?

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

Comment on Getopt::Declare parameter variables Select or Download Code

Replies are listed 'Best First'.
Re: Getopt::Declare parameter variables by Anonymous Monk on Aug 25, 2004 at 04:07 UTC
`#!/your/perl/here use strict; use warnings; use Getopt::Declare; unshift @ARGV, -one => 1, -two => 2 # <- defaults unless "@ARGV" =~ /(-help\|-version)/; my $options = Getopt::Declare->new(<<'SPEC'); -one <one:i> first param: (default = 1) [repeatable] {$::one = $one; defer{ die "\t -one ($::one) > -two ($::two)\n" if $::one > $::two } } -two <two:i> second param: (default = 2) [repeatable] {$::two = $two} SPEC print "one = $options->{-one}\n"; print "two = $options->{-two}\n";` [download]	[reply] [d/l]
Re^2: Getopt::Declare parameter variables by QM (Parson) on Aug 25, 2004 at 17:44 UTC
Thanks, I knew I didn't have my head on straight! There are 2 minor typos in your example, which `Getopt::Declare` makes easy to find. First, there doesn't appear to be a tab between the specifications and the descriptions (but this may be due to the cut and paste). Second, a blank line is needed between each parameter spec and the next. -QM -- Quantum Mechanics: The dreams stuff is made of	[reply] [d/l]