package MyModule;
use strict;
use warnings;

use Module::Load;

my $dd_loaded;

BEGIN {
    $dd_loaded = eval { autoload Data::Dump; 1; };
    use if ! $dd_loaded, 'Data::Dumper';
}

_mydump(\%INC);

sub _mydump{
    my ($ref) = @_;

    if ($dd_loaded){
        print "using Data::Dump dd\n";
        dd $ref;
    }
    else {
        print "using Data::Dumper\n";
        print Dumper $ref;
    }
}