Sam Brain


Params::Validate::Array - provide an alternative version of Param::Validate's validate() function which will return parameters as a list.


Version 0.03


This module's validate() function is a replacement for the Params::Validate module's validate() function, returning the arguments as a list, and not a hash as Params::Validate::validate() does.

This replacement validate() requires the argument descriptor to be an array reference, not a hash reference as in Params::Validate::validate().


  use Params::Validate::Array qw(SCALAR ARRAYREF validate ...);

  sub foo1 {
    my ($a, $b, $c) = validate( @_,
              # note the arrayref, not a hashref as in Params::Validate
              [ a => 1,   #  types of a, b, & c are 
                b => 0,   #+ unspecified. a is mandatory,
                c => 0,   #+ b & c optional

    print "a = $a\n";
    print "b = ", $b // "undefined", "\n";
    print "c = ", $c // "undefined", "\n";

  foo1(a => 'hello', c => 'there');
  # prints:
  #  a = hello
  #  b = undefined
  #  c = there

  foo1(b => 1, c => 'foo');
  # throws error:
  #   "Mandatory parameter 'a' missing in call to main::foo1 ..."


  sub foo2 {
    my ($x, $y) = validate( @_,
          # arrayref, not hashref
          [ x => {type => HASHREF, optional => 1},  #  hashref 'x' is optional,
            y => {type => SCALAR                },  #+ scalar 'y' mandatory

    $x->{$y} = 'foo'
      if defined $x;

Note that if this module's validate() function is called with a hashref argument descriptor, the behaviour reverts to that of Params::Validate::validate():

  use Params::Validate::Array qw(SCALAR HASHREF validate);

  sub foo3 {
    my %arg = validate( @_,
              # Note hashref
              { x => {type => HASHREF, optional => 1}, 
                y => {type => SCALAR                },

    print "y arg is ", $arg{y}, "\n";


Params::Validate::Array exports everything that Params::Validate does, including validate() and validate_pos() by default. The functions validate_with() and validation_options() as well as constants SCALAR, ARRAYREF, etc are also available for export. See Params::Validate for details.

Only the behaviour of validate() is changed, and only when the argument descriptor is an arrayref. All other routines are identical to those in Params::Validate (Except for validation_options() which will increment any stack_skip => ... argument to hide the extra layer of call stack).


my @args = validate(@_, [ descriptor ]);

In contrast to the validate() subroutine in Params::Validate, which is called as:

  my %args = validate(@_, { ... } );

(where the hashref argument {...} is a descriptor for the subroutine arguments to be validated), the Params::Validate::Array::validate() subroutine in this package is called as

  my ($arg1, $arg2, ...) = validate(@_, [ ... ] );

where the contents of the descriptor [...] are identical to those in the hashref descriptor {...} of the Params::Validate call.

In fact Params::Validate::Array::validate() is little more than a wrapper, and uses Params::Validate::validate() to do all the hard work.


Sam Brain, <samb at>


Please report any bugs or feature requests to bug-test at, or through the web interface at I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.


Thanks to Dave Rolsky for the Params::Validate and MooseX::Params::Validate modules, whose perl code and test suites I plagiarized shamelessly for this module.


Copyright 2011 Sam Brain.

This program is free software; you can redistribute it and/or modify it under the terms of either: the GNU General Public License as published by the Free Software Foundation; or the Artistic License.

See for more information.