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

In reply to Getopt::Declare parameter variables by QM

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