# perldoc > Specio::Constraint::Parameterizable

## 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:

    *   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.

    *   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.