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Named arguments in Perl5. Sorta.

by broquaint (Abbot)
on Oct 04, 2005 at 16:11 UTC ( #497312=snippet: print w/ replies, xml ) Need Help??

Description: Given a list of pairs the variable names matching the keys will automagically be assigned to the corresponding values.

I'd had it in the back of my mind that this could be achieved fairly simply, as demonstrated below, but as you can see it's not the most robust of methods. I'll CPAN-ify it if anyone wants a rather more sensible version of the code, and I'm sure documentation and tests wouldn't go amiss too.

Update: This code can now be found on CPAN going under the guise of Params::Named.

use strict;
use warnings;

use PadWalker 'peek_sub';
use List::Util 'first';

## Map named arguments to variables of those names.
sub getargs {
  my %args = do { package DB; () = caller 1; @DB::args };
  my $vals = peek_sub \&{(caller 1)[3]};
  my %res  = map { $_ => $args{substr($_, 1)} }
             grep exists $args{substr($_, 1)}, keys %$vals;
  my %map  = map {
    my $orig_arg  = \$_;
    my($ref_name) = first { $orig_arg == $vals->{$_} } keys %$vals;
    $ref_name => $orig_arg;
  } @_;

  ${ $map{$_} } = $res{$_}
    for keys %res;

  return \%res;
}

## Basic test of getargs();
sub foo {
  getargs my($this, $that, $theother);
  print "this is: $this\nthat is: $that\nand the other is: $theother\n
+";
}

## Have these pairs mapped to variables of the same name.
foo this     => "an argument",
    that     => "used to refer to things",
    theother => "is something else altogether";
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