Contract::Declare

Contract::Declare is a simple and lightweight system for defining typed contracts (interfaces) in Perl.

It provides a small DSL to specify method arguments and return types, with optional runtime validation.

Features

• Define strict typed interfaces (contracts) for your classes
• Optional runtime checking of method arguments and return values
• Minimalistic DSL: contract, interface, method, returns
• Integrates with Role::Tiny for easy role-based design
• No heavy dependencies, very fast

Installation

Install via CPAN:

cpanm Contract::Declare

Or manually:

perl Makefile.PL
make
make test
make install

Quick Start

package MyInterface;

use Contract::Declare;
use Standard::Types qw(Int Str);

contract 'MyInterface' => interface {
    method add_number => (Int), returns(Int);
    method get_name   => returns(Str);
};

package MyImpl;

sub new { bless {}, shift }
sub add_number { my ($self, $x) = @_; return $x + 1 }
sub get_name   { return "example" }

# Using the contract
my $impl = MyImpl->new;
my $obj  = MyInterface->new($impl);

say $obj->add_number(41);  # prints 42
say $obj->get_name;        # prints "example"

Environment Variables

| Variable | Description | |:---------|:-------------| | CONTRACT_DECLARE_CHECK_TYPES | Enables runtime validation of method arguments and return values if set to true | | CONTRACT_DECLARE_KEEP_CONTRACT | Keeps contract definitions in memory after building if set |

Example:

export CONTRACT_DECLARE_CHECK_TYPES=1

Contributing

Bug reports and pull requests are welcome!

Please submit issues and feature requests via GitHub Issues.

License

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

See the Artistic License 1.0 for details.

Author

Alexander Ponomarev (shootnix@gmail.com)

Project: GitHub Repository