# info > Specio::Constraint::Parameterizable

## [Specio::Constraint::PaUsertContributedSpecio::Constraint](https://www.chedong.com/phpMan.php/perldoc/Specio%3A%3AConstraint%3A%3APaUsertContributedSpecio%3A%3AConstraint/markdown)::[Parameterizable(3pm)](https://www.chedong.com/phpMan.php/man/Parameterizable/3pm/markdown)

## NAME
       [Specio::Constraint::Parameterizable](https://www.chedong.com/phpMan.php/perldoc/Specio%3A%3AConstraint%3A%3AParameterizable/markdown) - A class which represents
       parameterizable constraints

## VERSION
       version 0.47

## SYNOPSIS
           my $arrayref = t('ArrayRef');

           my $arrayref_of_int = $arrayref->parameterize( of => t('Int') );

## DESCRIPTION
       This class implements the API for parameterizable types like "ArrayRef"
       and "Maybe".

## API
       This class implements the same API as [Specio::Constraint::Simple](https://www.chedong.com/phpMan.php/perldoc/Specio%3A%3AConstraint%3A%3ASimple/markdown), with
       a few additions.

   [Specio::Constraint::Parameterizable](https://www.chedong.com/phpMan.php/perldoc/Specio%3A%3AConstraint%3A%3AParameterizable/markdown)->new(...)
       This class's constructor accepts two additional parameters:

       o   parameterized_constraint_generator

           This is a subroutine that generates a new constraint subroutine
           when the type is parameterized.

           It will be called as a method on the type and will be passed a
           single argument, the type object for the type parameter.

           This parameter is mutually exclusive with the
           "parameterized_inline_generator" parameter.

       o   parameterized_inline_generator

           This is a subroutine that generates a new inline generator
           subroutine when the type is parameterized.

           It will be called as a method on the
           [Specio::Constraint::Parameterized](https://www.chedong.com/phpMan.php/perldoc/Specio%3A%3AConstraint%3A%3AParameterized/markdown) object when that object needs to
           generate an inline constraint. It will receive the type parameter
           as the first argument and the variable name as a string as the
           second.

           This probably seems fairly confusing, so looking at the examples in
           the [Specio::Library::Builtins](https://www.chedong.com/phpMan.php/perldoc/Specio%3A%3ALibrary%3A%3ABuiltins/markdown) code may be helpful.

           This parameter is mutually exclusive with the
           "parameterized_constraint_generator" parameter.

   $type->parameterize(...)
       This method takes two arguments. The "of" argument should be an object
       which does the [Specio::Constraint::Role::Interface](https://www.chedong.com/phpMan.php/perldoc/Specio%3A%3AConstraint%3A%3ARole%3A%3AInterface/markdown) role, and is
       required.

       The other argument, "declared_at", is optional. If it is not given,
       then a new [Specio::DeclaredAt](https://www.chedong.com/phpMan.php/perldoc/Specio%3A%3ADeclaredAt/markdown) object is creating using a call stack
       depth of 1.

       This method returns a new [Specio::Constraint::Parameterized](https://www.chedong.com/phpMan.php/perldoc/Specio%3A%3AConstraint%3A%3AParameterized/markdown) object.

## SUPPORT
       Bugs may be submitted at
       <<https://github.com/houseabsolute/Specio/issues>>.

       I am also usually active on IRC as 'autarch' on "irc://irc.perl.org".

## SOURCE
       The source code repository for Specio can be found at
       <<https://github.com/houseabsolute/Specio>>.

## AUTHOR
       Dave Rolsky <<autarch@urth.org>>

## COPYRIGHT AND LICENSE
       This software is Copyright (c) 2012 - 2021 by Dave Rolsky.

       This is free software, licensed under:

         The Artistic License 2.0 (GPL Compatible)

       The full text of the license can be found in the LICENSE file included
       with this distribution.

perl v5.32.0                      [2021Specio::Constraint](https://www.chedong.com/phpMan.php/perldoc/2021Specio%3A%3AConstraint/markdown)::[Parameterizable(3pm)](https://www.chedong.com/phpMan.php/man/Parameterizable/3pm/markdown)