--- /dev/null
+package MooseX::Dependent;
+
+use 5.008;
+
+use strict;
+use warnings;
+
+our $VERSION = '0.01';
+our $AUTHORITY = 'cpan:JJNAPIORK';
+
+=head1 NAME
+
+MooseX::Dependent - Dependent L<MooseX::Types> constraints and L<Moose> attributes
+
+=head1 SYNOPSIS
+
+Given some L<MooseX::Types> declared as:
+
+ package MyApp::Types;
+
+ use MooseX::Types::Moose qw(Object, Int);
+ use MooseX::Dependent::Types qw(Dependent);
+ use Moosex::Types -declare => [qw(Set UniqueID)];
+
+ subtype Set,
+ as Object,
+ where {
+ shift->can('find');
+ };
+
+ subtype UniqueID,
+ as Dependent[Int, Set],
+ where {
+ my ($int, $set) = @_;
+ return $set->find($int) ? 0:1;
+ };
+
+Assuming 'Set' is a class that creates and manages sets of values (lists of
+unique but unordered values) with a method '->find($n)', which returns true when
+$n is a member of the set and which you instantiate like so:
+
+ my $set_obj = Set->new(1,2,3,4,5); ## 1..5 are member of Set $set_obj'
+
+You can then use this $set_obj as a parameter on the previously declared type
+constraint 'UniqueID'. This $set_obj become part of the constraint (you can't
+actually use the constraint without it.)
+
+ UniqueID[$set_obj]->check(1); ## Not OK, since one isn't unique in $set_obj
+ UniqueID[$set_obj]->check(100); ## OK, since 100 isn't in the set.
+
+Additionally, you can use these dependent types on your L<Moose> based classes
+and set the dependency target to the value of another attribute or method:
+
+ TDB: Following is tentative
+
+ package MyApp::MyClass;
+
+ use Moose;
+ use MooseX::Dependent (or maybe a role, or traits...?)
+ use MooseX::Types::Moose qw();
+ use MyApp::Types qw(UniqueID Set);
+
+ has people => (is=>'ro', isa=>Set, required=>1);
+ has id => (is=>'ro', isa=>UniqueID, required=>1);
+
+Please see the test cases for more examples.
+
+=head1 DESCRIPTION
+
+A dependent type is a type constraint whose validity is dependent on a second
+value. You defined the dependent type constraint with a primary type constraint
+(such as 'Int') a 'constraining' value type constraint (such as a 'Set' object)
+and a coderef (such as a 'where' clause in your type constraint declaration)
+which will compare the incoming value to be checked with a value that conforms
+to the constraining type constraint.
+
+Once created, you can use dependent types directly, or in your L<Moose> based
+attributes and methods (if you are using L<MooseX::Declare>). Attribute traits
+are available to make it easy to assign the dependency to the value of another
+attribute or another method.
+
+=head1 TYPE CONSTRAINTS
+
+All type constraints are defined in L<MooseX::Dependent::Types>. Please see
+that class for more documentation and examples of how to create type constraint
+libraries using dependent types.
+
+=cut
+
+=head1 ATTRIBUTE TRAITS
+
+ TBD
+
+=head1 SEE ALSO
+
+L<Moose>, L<Moose::Meta::TypeConstraints>, L<MooseX::Types>
+
+=head1 AUTHOR
+
+John Napiorkowski, C<< <jjnapiork@cpan.org> >>
+
+=head1 COPYRIGHT & LICENSE
+
+This program is free software; you can redistribute it and/or modify
+it under the same terms as Perl itself.
+
+=cut
+
+1;
-package MooseX::Types::Dependent;
+package MooseX::Dependent::Types;
use 5.008;
use Moose::Util::TypeConstraints;
-use MooseX::Meta::TypeConstraint::Dependent;
-use MooseX::Types -declare => [qw(Depending)];
+use MooseX::Dependent::Meta::TypeConstraint::Parameterizable;
+use MooseX::Types -declare => [qw(Dependent)];
our $VERSION = '0.01';
our $AUTHORITY = 'cpan:JJNAPIORK';
=head1 NAME
-MooseX::Types::Dependent - L<MooseX::Types> constraints that depend on values.
+MooseX::Dependent::Types - L<MooseX::Types> constraints that depend on values.
=head1 SYNOPSIS
- subtype UniqueInt,
- as Depending[
- Int,
- sub {
- shift->exists(shift) ? 0:1;
- },
- Set,
- ];
-
- subtype UniqueInt,
- as Depending {
- shift->exists(shift) ? 0:1;
- } [Int, Set];
-
-Please see the test cases for more examples.
-
-=head1 DEFINITIONS
-
-The following is a list of terms used in this documentation.
-
-=head2 Dependent Type Constraint
-
-=head2 Check Value
+Within your L<MooseX::Types> declared library module:
-=head2 Constraining Type Constraint
-
-=head2 Constraining Value
+ use MooseX::Dependent::Types qw(Dependent);
+
+ subtype UniqueID,
+ as Dependent[Int, Set],
+ where {
+ my ($int, $set) = @_;
+ return $set->find($int) ? 0:1;
+ };
=head1 DESCRIPTION
-A dependent type is a type constraint whose validity is dependent on a second
-value. You defined the dependent type constraint with a primary type constraint
-(such as 'Int') a 'constraining' value type constraint (such as a Set object)
-and a coderef which will compare the incoming value to be checked with a value
-that conforms to the constraining type constraint. Typically there should be a
-comparision operator between the check value and the constraining value
-
-=head2 Subtyping a Dependent type constraints
-
-TDB: Need discussion and examples.
-
+A L<MooseX::Types> library for creating dependent types. A dependent type
+constraint for all intents and uses is a subclass of a parent type, but adds a
+secondary type parameter which is available to constraint callbacks (such as
+inside the 'where' clause) or in the coercions.
+
+This allows you to create a type that has additional runtime advice, such as a
+set of numbers within which another number must be unique, or allowable ranges
+for a integer, such as in:
+
+ subtype Range,
+ as Dict[max=>Int, min=>Int],
+ where {
+ my ($range) = @_;
+ return $range->{max} > $range->{min};
+ };
+
+ subtype RangedInt,
+ as Dependent[Int, Range],
+ where {
+ my ($value, $range) = @_;
+ return ($value >= $range->{min} &&
+ $value =< $range->{max});
+ };
+
+ RangedInt[{min=>10,max=>100}]->check(50); ## OK
+ RangedInt[{min=>50, max=>75}]->check(99); ## Not OK, 99 exceeds max
+ RangedInt[{min=>99, max=>10}]->check(10); ## Not OK, not a valid Range!
+
+Please note that for ArrayRef or HashRef dependent type constraints, as in the
+example above, as a convenience we automatically ref the incoming type
+parameters, so that the above could also be written as:
+
+ RangedInt[min=>10,max=>100]->check(50); ## OK
+ RangedInt[min=>50, max=>75]->check(99); ## Not OK, 99 exceeds max
+ RangedInt[min=>99, max=>10]->check(10); ## Not OK, not a valid Range!
+
+This is the preferred syntax, as it improve readability and adds to the
+conciseness of your type constraint declarations. An exception wil be thrown if
+your type parameters don't match the required reference type.
+
+==head2 Subtyping a Dependent type constraints
+
+When subclassing a dependent type you must be careful to match either the
+required type parameter type constraint, or if re-parameterizing, the new
+type constraints are a subtype of the parent. For example:
+
+ subtype RangedInt,
+ as Dependent[Int, Range],
+ where {
+ my ($value, $range) = @_;
+ return ($value >= $range->{min} &&
+ $value =< $range->{max});
+ };
+
+Example subtype with additional constraints:
+
+ subtype PositiveRangedInt,
+ as RangedInt,
+ where {
+ shift >= 0;
+ };
+
+Or you could have done the following instead (example of re-paramterizing)
+
+ ## Subtype of Int for positive numbers
+ subtype PositiveInt,
+ as Int,
+ where {
+ shift >= 0;
+ };
+
+ ## subtype Range to re-parameterize Range with subtypes
+ subtype PositveRange,
+ as Range[max=>PositiveInt, min=>PositiveInt];
+
+ ## create subtype via reparameterizing
+ subtype PositiveRangedInt,
+ as RangedInt[PositveRange];
+
+Notice how re-parameterizing the dependent type 'RangedInt' works slightly
+differently from re-parameterizing 'PositiveRange'? Although it initially takes
+two type constraint values to declare a dependent type, should you wish to
+later re-parameterize it, you only use a subtype of the second type parameter
+(the dependent type constraint) since the first type constraint sets the parent
+type for the dependent type. In other words, given the example above, a type
+constraint of 'RangedInt' would have a parent of 'Int', not 'Dependent' and for
+all intends and uses you could stick it wherever you'd need an Int.
+
+ subtype NameAge,
+ as Tuple[Str, Int];
+
+ ## re-parameterized subtypes of NameAge containing a Dependent Int
+ subtype NameBetween18and35Age,
+ as NameAge[
+ Str,
+ PositiveRangedInt[min=>18,max=>35],
+ ];
+
+One caveat is that you can't stick an unparameterized dependent type inside a
+structure, such as L<MooseX::Types::Structured> since that would require the
+ability to convert a 'containing' type constraint into a dependent type, which
+is a capacity we current don't have.
+
=head2 Coercions
-TBD: Need discussion and example of coercions working for both the
-constrainted and dependent type constraint.
+ TBD: Need discussion and example of coercions working for both the
+ constrainted and dependent type constraint.
+
+ subtype OlderThanAge,
+ as Dependent[Int, Dict[older_than=>Int]],
+ where {
+ my ($value, $dict) = @_;
+ return $value > $dict->{older_than} ? 1:0;
+ };
+
+Which should work like:
+
+ OlderThanAge[{older_than=>25}]->check(39); ## is OK
+
+ coerce OlderThanAge,
+ from Tuple[Int, Int],
+ via {
+ my ($int, $int);
+ return [$int, {older_than=>$int}];
+ };
=head2 Recursion
Newer versions of L<MooseX::Types> support recursive type constraints. That is
you can include a type constraint as a contained type constraint of itself.
Recursion is support in both the dependent and constraining type constraint. For
-example:
+example, if we assume an Object hierarchy like Food -> [Grass, Meat]
+
+ TODO: DOES THIS EXAMPLE MAKE SENSE?
+
+ subtype Food,
+ as Dependent[Food, Food],
+ where {
+ my ($value, $allowed_food_type) = @_;
+ return $value->isa($allowed_food_type);
+ };
+
+ my $grass = Food::Grass->new;
+ my $meat = Food::Meat->new;
+ my $vegetarian = Food[$grass];
+
+ $vegetarian->check($grass); ## Grass is the allowed food of a vegetarian
+ $vegetarian->check($meat); ## BANG, vegetarian can't eat meat!
=head1 TYPE CONSTRAINTS
This type library defines the following constraints.
-=head2 Depending[$dependent_tc, $codref, $constraining_tc]
-
-Create a subtype of $dependent_tc that is constrainted by a value that is a
-valid $constraining_tc using $coderef. For example:
-
- subtype GreaterThanInt,
- as Depending[
- Int,
- sub {
- my($constraining_value, $check_value) = @_;
- return $constraining_value > $check_value ? 1:0;
- },
- Int,
- ];
+=head2 Dependent[ParentTypeConstraint, DependentValueTypeConstraint]
-Note that the coderef is passed the constraining value and the check value as an
-Array NOT an ArrayRef.
+Create a subtype of ParentTypeConstraint with a dependency on a value that can
+pass the DependentValueTypeConstraint. If DependentValueTypeConstraint is empty
+we default to the 'Any' type constraint (see L<Moose::Util::TypeConstraints>).
-This would create a type constraint that takes an integer and checks it against
-a second integer, requiring that the check value is greater. For example:
-
- GreaterThanInt->check([5,10]); ## Fails, 5 is less than 10
- GreaterThanInt->check(['a',10]); ## Fails, 'a' is not an Int.
- GreaterThanInt->check([5,'b']); ## Fails, 'b' is not an Int either.
- GreaterThanInt->check([10,5]); ## Success, 10 is greater than 5.
-
-=head1 EXAMPLES
-
-Here are some additional example usage for structured types. All examples can
-be found also in the 't/examples.t' test. Your contributions are also welcomed.
-
-TBD
+This creates a type constraint which must be further parameterized at later time
+before it can be used to ->check or ->validate a value. Attempting to do so
+will cause an exception.
=cut
Moose::Util::TypeConstraints::get_type_constraint_registry->add_type_constraint(
- MooseX::Meta::TypeConstraint::Dependent->new(
- name => "MooseX::Types::Dependent::Depending" ,
+ MooseX::Dependent::Meta::TypeConstraint::Parameterizable->new(
+ name => 'MooseX::Dependent::Types::Dependent',
parent => find_type_constraint('ArrayRef'),
constraint_generator=> sub {
my ($dependent_val, $callback, $constraining_val) = @_;
)
);
-=head1 SEE ALSO
-
-The following modules or resources may be of interest.
-
-L<Moose>, L<MooseX::Types>, L<Moose::Meta::TypeConstraint>,
-L<MooseX::Meta::TypeConstraint::Dependent>
-
-=head1 TODO
-
-Here's a list of stuff I would be happy to get volunteers helping with:
-
-=over 4
-
-=item Examples
-
-Examples of useful code with both POD and ideally a test case to show it
-working.
-
-=back
-
=head1 AUTHOR
John Napiorkowski, C<< <jjnapiork@cpan.org> >>
projects / gitmo/MooseX-Dependent.git / commitdiff