Attribute::Params::Validate(3) Define validation through subroutine attributes


version 1.13


use Attribute::Params::Validate qw(:all);
# takes named params (hash or hashref)
# foo is mandatory, bar is optional
sub foo : Validate( foo => 1, bar => 0 )
# takes positional params
# first two are mandatory, third is optional
sub bar : ValidatePos( 1, 1, 0 )
# for some reason Perl insists that the entire attribute be on one line
sub foo2 : Validate( foo => { type => ARRAYREF }, bar => { can => [ 'print', 'flush', 'frobnicate' ] }, baz => { type => SCALAR, callbacks => { 'numbers only' => sub { shift() =~ /^\d+$/ }, 'less than 90' => sub { shift() < 90 } } } )
# note that this is marked as a method. This is very important!
sub baz : Validate( foo => { type => ARRAYREF }, bar => { isa => 'Frobnicator' } ) method


The Attribute::Params::Validate module allows you to validate method or function call parameters just like Params::Validate does. However, this module allows you to specify your validation spec as an attribute, rather than by calling the "validate" routine.

Please see Params::Validate for more information on how you can specify what validation is performed.


This module exports everything that Params::Validate does except for the "validate" and "validate_pos" subroutines.


  • Validate

    This attribute corresponds to the "validate" subroutine in Params::Validate.

  • ValidatePos

    This attribute corresponds to the "validate_pos" subroutine in Params::Validate.


If you are using this module to mark methods for validation, as opposed to subroutines, it is crucial that you mark these methods with the ":method" attribute, as well as the "Validate" or "ValidatePos" attribute.

If you do not do this, then the object or class used in the method call will be passed to the validation routines, which is probably not what you want.


You must put all the arguments to the "Validate" or "ValidatePos" attribute on a single line, or Perl will complain.



This software is Copyright (c) 2014 by Dave Rolsky and Ilya Martynov.

This is free software, licensed under:

  The Artistic License 2.0 (GPL Compatible)