With what you look to be trying, try this:

# Takes a package name, loads the associated module.
sub load_module {
  my $pkg = shift;
  my $file = $pkg;
  $file =~ s/::/\//g;
  $file .= ".pm";
  require $file;
}

# Then at the start of your code, assuming you already
# processed the module_name into $module
load_module($module);
my $parser = $module->new();
# Proceed...
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If you go this approach you should understand the basics of Perl's OO support. You should definitely understand bless, have read perltoot, etc.