Params::ValidationCompiler - Build an optimized subroutine parameter validator once, use it forever


version 0.09


    use Types::Standard qw( Int Str );
    use Params::ValidationCompiler qw( validation_for );

        my $check = validation_for(
            params => {
                foo => { type => Int },
                bar => {
                    type     => Str,
                    optional => 1,
                baz => {
                    type    => Int,
                    default => 42,

        sub do_something {
            my %args = $check->(@_);


This is very alpha. The module name could change. Everything could change. You have been warned.

Create a customized, optimized, non-lobotomized, uncompromised, and thoroughly specialized parameter checking subroutine.


This module has two options exports, validation_for and source_for. Both of these subs accept the same options:

  • params

    An arrayref or hashref containing a parameter specification.

    If you pass an arrayref, the check will expect positional params. Each member of the arrayref represents a single parameter to validate.

    If you pass a hashref then it will expect named params. For hashrefs, the parameters names are the keys and the specs are the values.

    The spec can contain either a boolean or hashref. If the spec is a boolean, this indicates required (true) or optional (false).

    The hashref accepts the following keys:

    • type

      A type object. This can be a Moose type (from Moose or MooseX::Types), a Type::Tiny type, or a Specio type.

      If the type has coercions, those will always be used.

    • default

      This can either be a simple (non-reference) scalar or a subroutine reference. The sub ref will be called without any arguments (for now).

    • optional

      A boolean indicating whether or not the parameter is optional. By default, parameters are required unless you provide a default.

  • slurpy

    If this is a simple true value, then the generated subroutine accepts additional arguments not specified in params. By default, extra arguments cause an exception.

    You can also pass a type constraint here, in which case all extra arguments must be values of the specified type.


This returns a subroutine that implements the specific parameter checking. Pass this the arguments in @_ and it will return a hash of parameters or throw an exception. The generated subroutine accepts either a hash or a single hashref.

For now, you must shift off the invocant yourself.

This subroutine accepts an additional parameter:

  • name

    If this is given, then the generated subroutine will be named using Sub::Name. This is strongly recommended as it makes it possible to distinguish different check subroutines when profiling or in stack traces.

    Note that you must install Sub::Name yourself separately, as it is not required by this distribution, in order to avoid requiring a compiler.


This returns a two element list. The first is a string containing the source code for the generated sub. The second is a hashref of "environment" variables to be used when generating the subroutine. These are the arguments that are passed to Eval::Closure.


Bugs may be submitted through the RT bug tracker (or

I am also usually active on IRC as 'drolsky' on irc://


If you'd like to thank me for the work I've done on this module, please consider making a "donation" to me via PayPal. I spend a lot of free time creating free software, and would appreciate any support you'd care to offer.

Please note that I am not suggesting that you must do this in order for me to continue working on this particular software. I will continue to do so, inasmuch as I have in the past, for as long as it interests me.

Similarly, a donation made in this way will probably not make me work on this software much more, unless I get so many donations that I can consider working on free software full time (let's all have a chuckle at that together).

To donate, log into PayPal and send money to, or use the button at


Dave Rolsky <>


This software is Copyright (c) 2016 by Dave Rolsky.

This is free software, licensed under:

  The Artistic License 2.0 (GPL Compatible)