NAME MooseX::Types::Structured; Structured Type Constraints for Moose SYNOPSIS The following is example usage for this module. You can define a class that has an attribute with a structured type like so: package MyApp::MyClass; use Moose; use MooseX::Types::Moose qw(Str Int); use MooseX::Types::Structured qw(Dict Tuple); has name => (isa=>Dict[first_name=>Str, last_name=>Str]); Then you can instantiate this class with something like: my $instance = MyApp::MyClass->new( name=>{first_name=>'John', last_name=>'Napiorkowski'}, ); But all of these would cause an error: my $instance = MyApp::MyClass->new(name=>'John'); my $instance = MyApp::MyClass->new(name=>{first_name=>'John'}); my $instance = MyApp::MyClass->new(name=>{first_name=>'John', age=>39}); Please see the test cases for more examples. DESCRIPTION This type library enables structured type constraints. Basically, this is very similar to parameterized constraints that are built into the core Moose types, except that you are allowed to define the container's entire structure. For example, you could define a parameterized constraint like so: subtype HashOfInts, as Hashref[Int]; which would constraint a value to something like [1,2,3,...] and so one. A structured constraint like so: subtype StringFollowedByInt, as Tuple[Str,Int]; would constrain it's value to something like ['hello', 111]; These structures can be as simple or elaborate as you wish. You can even combine various structured, parameterized and simple constraints all together: subtype crazy, as Tuple[Int, Dict[name=>Str, age=>Int], ArrayRef[Int]]; Which would match "[1, {name=>'John', age=>25},[10,11,12]]". You should exercise some care as to whether or not your complex structured constraints would be better off contained by a real object as in the following example: { package MyApp::MyStruct; use Moose; has $_ for qw(name age); package MyApp::MyClass; use Moose; has person => (isa=>'MyApp::MyStruct'); } my $instance = MyApp::MyClass ->new( person=>MyApp::MyStruct->new(name=>'John', age=>39) ); This method may take some additional time to setup but will give you more flexibility. However, structured constraints are highly compatible with this method, granting some interesting possibilities for coercion. Try: subtype 'MyStruct', as 'MyApp::MyStruct'; coerce 'MyStruct', from (Dict[name=>Str, age=>Int]), via { MyApp::MyStruct->new(%$_); }, from (Dict[last_name=>Str, first_name=>Str, dob=>DateTime]), via { my $name = $_->{first_name} .' '. $_->{last_name}; my $age = DateTime->now - $_->{dob}; MyApp::MyStruct->new( name=>$name, age=>$age->years ); }; Subtyping a structured subtype You need to exercise some care when you try to subtype a structured type as in this example: subtype Person, as Dict[name=>Str, age=>iIt]; subtype FriendlyPerson, as Person[name=>Str, age=>Int, totalFriends=>Int]; This will actually work BUT you have to take care that the subtype has a structure that does not contradict the structure of it's parent. For now the above works, but I will probably clarify how this works at a future point, so it's recommended to avoid (should not realy be needed so much anyway). For now this is supported in an EXPERIMENTAL way. In the future we will probably clarify how to augment existing structured types. Coercions Coercions currently work for 'one level' deep. That is you can do: subtype Person, as Dict[name=>Str, age=>Int]; subtype Fullname, as Dict[first=>Str, last=>Str]; coerce Person, from BlessedPersonObject, via { +{name=>$_->name, age=>$_->age} }, from ArrayRef, via { +{name=>$_->[0], age=>$_->[1] }, from Dict[fullname=>Fullname, dob=>DateTime], via { my $age = $_->dob - DateTime->now; +{ name=> $_->{fullname}->{first} .' '. $_->{fullname}->{last}, age=>$age->years } }; And that should just work as expected. However, if there are any 'inner' coercions, such as a coercion on 'Fullname' or on 'DateTime', that coercion won't currently get activated. Please see the test '07-coerce.t' for a more detailed example. TYPE CONSTRAINTS This type library defines the following constraints. Tuple[@constraints] This defines an arrayref based constraint which allows you to validate a specific list of constraints. For example: Tuple[Int,Str]; ## Validates [1,'hello'] Tuple[Str|Object, Int]; ##Validates ['hello', 1] or [$object, 2] Dict [%constraints] This defines a hashref based constraint which allowed you to validate a specific hashref. For example: Dict[name=>Str, age=>Int]; ## Validates {name=>'John', age=>39} SEE ALSO The following modules or resources may be of interest. Moose, MooseX::TypeLibrary, Moose::Meta::TypeConstraint, MooseX::Meta::TypeConstraint::Structured TODO Need to clarify deep coercions, need to clarify subtypes of subtypes. AUTHOR John Napiorkowski, "" COPYRIGHT & LICENSE This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.