# phpman > perldoc > Specio::Constraint::Structurable

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

## VERSION
    version 0.47

## SYNOPSIS
        my $tuple = t('Tuple');

        my $tuple_of_str_int = $tuple->parameterize( of => [ t('Str'), t('Int') ] );

## DESCRIPTION
    This class implements the API for structurable types like "Dict", "Map"< and "Tuple".

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

    *   parameterization_args_builder

        This is a subroutine that takes the values passed to "of" and returns a hash of named
        arguments. These arguments will then be passed into the "structured_constraint_generator" or
        "structured_inline_generator".

        This should also do argument checking to make sure that the argument passed are valid. For
        example, the "Tuple" type turns the arrayref passed to "of" into a hash, along the way
        checking that the caller did not do things like interleave optional and required elements or
        mix optional and slurpy together in the definition.

        This parameter is required.

    *   name_builder

        This is a subroutine that is called to generate a name for the structured type when it is
        created. This will be called as a method on the "[Specio::Constraint::Structurable](https://www.chedong.com/phpMan.php/perldoc/Specio%3A%3AConstraint%3A%3AStructurable/markdown)" object.
        It will be passed the hash of arguments returned by the "parameterization_args_builder".

        This parameter is required.

    *   structured_constraint_generator

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

        It will be called as a method on the type and will be passed the hash of arguments returned
        by the "parameterization_args_builder".

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

        This parameter or the "structured_inline_generator" parameter is required.

    *   structured_inline_generator

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

        It will be called as a method on the [Specio::Constraint::Structured](https://www.chedong.com/phpMan.php/perldoc/Specio%3A%3AConstraint%3A%3AStructured/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.

        The remaining arguments will be the parameter hash returned by the
        "parameterization_args_builder".

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

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

        This parameter or the "structured_constraint_generator" parameter is required.

  $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::Structured](https://www.chedong.com/phpMan.php/perldoc/Specio%3A%3AConstraint%3A%3AStructured/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.