Easiest way to do it is to check how many parameters you're being passed, or work from the other end. 
sub verify{
  my $optional;
  $optional = (@_ == 2) ? shift : "default value";
  my $ref = shift;
  ...
}

[download]
or 
sub verify{
  my $ref = pop;
  my $optional = pop; #becomes undef if only one param
}

[download]

In reply to Re: Optional parameter before reference by Eimi Metamorphoumai
in thread Optional parameter before reference by Neutron Jack

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