Attribute::Params::Validate - Define validation through subroutine attributes


version 1.21


  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 )
      # insert code here

  # takes positional params
  # first two are mandatory, third is optional
  sub bar : ValidatePos( 1, 1, 0 )
      # insert code here

  # 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 } } } )
      # insert code here

  # note that this is marked as a method.  This is very important!
  sub baz : Validate( foo => { type => ARRAYREF }, bar => { isa => 'Frobnicator' } ) method
      # insert code here


This module is currently unmaintained. I do not recommend using it. It is a failed experiment. If you would like to take over maintenance of this module, please contact me at

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.


Please submit bugs and patches to the CPAN RT system at or via email at




Dave Rolsky <>


This software is Copyright (c) 2015 by Dave Rolsky.

This is free software, licensed under:

  The Artistic License 2.0 (GPL Compatible)