use 5.008;
-our $VERSION = '0.01';
+our $VERSION = '0.02';
$VERSION = eval $VERSION;
use Moose::Util::TypeConstraints;
=head1 SYNOPSIS
-Within your L<MooseX::Types> declared library module:
+The follow is example usage.
+ package Test::MooseX::Types::Parameterizable::Synopsis;
+
+ use Moose;
use MooseX::Types::Parameterizable qw(Parameterizable);
-
- subtype Set,
- as class_type("Set::Scalar");
+ use MooseX::Types::Moose qw(Str Int ArrayRef);
+ use MooseX::Types -declare=>[qw(Varchar)];
+
+ ## Create a type constraint that is a string but parameterizes an integer
+ ## that is used as a maximum length constraint on that string, similar to
+ ## a SQL Varchar database type.
+
+ subtype Varchar,
+ as Parameterizable[Str,Int],
+ where {
+ my($string, $int) = @_;
+ $int >= length($string) ? 1:0;
+ },
+ message { "'$_' is too long" };
+
+ ## Coerce an ArrayRef to a string via concatenation.
+
+ coerce Varchar,
+ from ArrayRef,
+ via {
+ my ($arrayref, $int) = @_;
+ join('', @$arrayref);
+ };
+
+ has 'varchar_five' => (isa=>Varchar[5], is=>'ro', coerce=>1);
+ has 'varchar_ten' => (isa=>Varchar[10], is=>'ro');
+
+ ## Object created since attributes are valid
+ my $object1 = __PACKAGE__->new(
+ varchar_five => '1234',
+ varchar_ten => '123456789',
+ );
+
+ ## Dies with an invalid constraint for 'varchar_five'
+ my $object2 = __PACKAGE__->new(
+ varchar_five => '12345678', ## too long!
+ varchar_ten => '123456789',
+ );
+
+ ## varchar_five coerces as expected
+ my $object3 = __PACKAGE__->new(
+ varchar_five => [qw/aa bb/], ## coerces to "aabb"
+ varchar_ten => '123456789',
+ );
+
+See t/05-pod-examples.t for runnable versions of all POD code
+
+=head1 DESCRIPTION
+
+A L<MooseX::Types> library for creating parameterizable types. A parameterizable
+type constraint for all intents and uses is a subclass of a parent type, but
+adds additional type parameters which are available to constraint callbacks
+(such as inside the 'where' clause of a type constraint definition) or in the
+coercions.
+
+If you have L<Moose> experience, you probably are familiar with the builtin
+parameterizable type constraints 'ArrayRef' and 'HashRef'. This type constraint
+lets you generate your own versions of parameterized constraints that work
+similarly. See L<Moose::Util::TypeConstraints> for more.
- subtype UniqueInt,
- as Parameterizable[Int, Set],
+Using this type constraint, you can generate new type constraints that have
+additional runtime advice, such as being able to specify maximum and minimum
+values for an Int (integer) type constraint:
+
+ subtype Range,
+ as Dict[max=>Int, min=>Int],
where {
- my ($int, $set) = @_;
- return !$set->has($int);
+ my ($range) = @_;
+ return $range->{max} > $range->{min};
};
-
- subtype PositiveSet,
- as Set,
- where {
- my ($set) = @_;
- return !grep {$_ <0 } $set->members;
- };
-
- subtype PositiveUniqueInt,
- as UniqueInt[PositiveSet];
-
- my $set = Set::Scalar->new(1,2,3);
-
- UniqueInt([$set])->check(100); ## Okay, 100 isn't in (1,2,3)
- UniqueInt([$set])->check(-99); ## Okay, -99 isn't in (1,2,3)
- UniqueInt([$set])->check(2); ## Not OK, 2 is in (1,2,3)
-
- PositiveUniqueInt([$set])->check(100); ## Okay, 100 isn't in (1,2,3)
- PositiveUniqueInt([$set])->check(-99); ## Not OK, -99 not Positive Int
- PositiveUniqueInt([$set])->check(2); ## Not OK, 2 is in (1,2,3)
-
- my $negative_set = Set::Scalar->new(-1,-2,-3);
-
- UniqueInt([$negative_set])->check(100); ## Throws exception
-
-=head1 DESCRIPTION
-A L<MooseX::Types> library for creating parameterizable types. A parameterizable 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} > $range->{min};
- };
-
- subtype RangedInt,
- as Parameterizable[Int, Range],
- where {
- my ($value, $range) = @_;
- return ($value >= $range->{min} &&
- $value <= $range->{max});
- };
-
- RangedInt([{min=>10,max=>100}])->check(50); ## OK
- RangedInt([{min=>50, max=>75}])->check(99); ## Not OK, 99 exceeds max
-
-This throws a hard Moose exception. You'll need to capture it in an eval or
-related exception catching system (see L<TryCatch>).
-
- RangedInt([{min=>99, max=>10}])->check(10); ## Not OK, not a valid Range!
+ subtype RangedInt,
+ as Parameterizable[Int, Range],
+ where {
+ my ($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
+
+The type parameter must be valid against the type constraint given. If you pass
+an invalid value this throws a hard Moose exception. You'll need to capture it
+in an eval or related exception catching system (see L<TryCatch> or <Try::Tiny>.)
+For example the following would throw a hard error (and not just return false)
+
+ RangedInt([{min=>99, max=>10}])->check(10); ## Not OK, not a valid Range!
If you can't accept a hard exception here, you'll need to test the constraining
values first, as in:
- my $range = {min=>99, max=>10};
- if(my $err = Range->validate($range)) {
- ## Handle #$err
- } else {
- RangedInt($range)->check(99);
- }
-
+ my $range = {min=>99, max=>10};
+ if(my $err = Range->validate($range)) {
+ ## Handle #$err
+ } else {
+ RangedInt($range)->check(99);
+ }
+
Please note that for ArrayRef or HashRef parameterizable 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); ## Exception, not a valid Range!
+ 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); ## Exception, 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.
-Also not that if you 'chain' parameterization results with a method call like:
+Also note that if you 'chain' parameterization results with a method call like:
- TypeConstraint([$ob])->method;
-
+ TypeConstraint([$ob])->method;
+
You need to have the "(...)" around the ArrayRef in the Type Constraint
-parameters. This seems to have something to do with the precendent level of
-"->". Patches or thoughts welcomed. You only need to do this in the above
-case which I imagine is not a very common case.
+parameters. You can skip the wrapping parenthesis in the most common cases,
+such as when you use the type constraint in the options section of a L<Moose>
+attribute declaration, or when defining type libraries.
==head2 Subtyping a Parameterizable type constraints
required type parameter type constraint, or if re-parameterizing, the new
type constraints are a subtype of the parent. For example:
- subtype RangedInt,
- as Parameterizable[Int, Range],
- where {
- my ($value, $range) = @_;
- return ($value >= $range->{min} &&
- $value =< $range->{max});
- };
+ subtype RangedInt,
+ as Parameterizable[Int, Range],
+ where {
+ my ($value, $range) = @_;
+ return ($value >= $range->{min} &&
+ $value =< $range->{max});
+ };
Example subtype with additional constraints:
- subtype PositiveRangedInt,
- as RangedInt,
- where {
- shift >= 0;
- };
-
-Or you could have done the following instead:
-
- ## Subtype of Int for positive numbers
- subtype PositiveInt,
- as Int,
- where {
- my ($value, $range) = @_;
- return $value >= 0;
- };
-
- ## subtype Range to re-parameterize Range with subtypes
- subtype PositiveRange,
- as Range[max=>PositiveInt, min=>PositiveInt];
-
- ## create subtype via reparameterizing
- subtype PositiveRangedInt,
- as RangedInt[PositiveRange];
+ subtype PositiveRangedInt,
+ as RangedInt,
+ where {
+ shift >= 0;
+ };
+
+In this case you'd now have a parameterizable type constraint called which
+would work like:
+
+ Test::More::ok PositiveRangedInt([{min=>-10, max=>75}])->check(5);
+ Test::More::ok !PositiveRangedInt([{min=>-10, max=>75}])->check(-5);
+
+Of course the above is somewhat counter-intuitive to the reader, since we have
+defined our 'RangedInt' in such as way as to let you declare negative ranges.
+For the moment each type constraint rule is apply without knowledge of any
+other rule, nor can a rule 'inform' existing rules. This is a limitation of
+the current system. However, you could instead do the following:
+
+
+ ## Subtype of Int for positive numbers
+ subtype PositiveInt,
+ as Int,
+ where {
+ my ($value, $range) = @_;
+ return $value >= 0;
+ };
+
+ ## subtype Range to re-parameterize Range with subtypes
+ subtype PositiveRange,
+ as Range[max=>PositiveInt, min=>PositiveInt];
+
+ ## create subtype via reparameterizing
+ subtype PositiveRangedInt,
+ as RangedInt[PositiveRange];
+
+This would constrain values in the same way as the previous type constraint but
+have the bonus that you'd throw a hard exception if you try to use an incorrect
+range:
+
+ Test::More::ok PositiveRangedInt([{min=>10, max=>75}])->check(15); ## OK
+ Test::More::ok !PositiveRangedInt([{min=>-10, max=>75}])->check(-5); ## Dies
Notice how re-parameterizing the parameterizable type 'RangedInt' works slightly
differently from re-parameterizing 'PositiveRange' Although it initially takes
two type constraint values to declare a parameterizable type, should you wish to
-later re-parameterize it, you only use a subtype of the second type parameter
-(the parameterizable type constraint) since the first type constraint sets the parent
-type for the parameterizable type. In other words, given the example above, a type
-constraint of 'RangedInt' would have a parent of 'Int', not 'Parameterizable' 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 Parameterizable Int
- subtype NameBetween18and35Age,
- as NameAge[
- Str,
- PositiveRangedInt[min=>18,max=>35],
- ];
-
-One caveat is that you can't stick an unparameterized parameterizable type inside a
-structure, such as L<MooseX::Types::Structured> since that would require the
-ability to convert a 'containing' type constraint into a parameterizable type, which
-is a capacity we current don't have.
-
+later re-parameterize it, you only use a subtype of the extra type parameter
+(the parameterizable type constraints) since the first type constraint sets the
+parent type for the parameterizable type.
+
+In other words, given the example above, a type constraint of 'RangedInt' would
+have a parent of 'Int', not 'Parameterizable' and for all intends and uses you
+could stick it wherever you'd need an Int.
+
=head2 Coercions
Parameterizable types have some limited support for coercions. Several things must
be kept in mind. The first is that the coercion targets the type constraint
-which is being made parameterizable, Not the parameterizable type. So for example if you
+which is being made parameterizable, Not the parameterized type. So for example if you
create a Parameterizable type like:
- subtype RequiredAgeInYears,
- as Int;
+ subtype RequiredAgeInYears,
+ as Int;
- subtype PersonOverAge,
- as Parameterizable[Person, RequiredAgeInYears]
- where {
- my ($person, $required_years_old) = @_;
- return $person->years_old > $required_years_old;
- }
+ subtype PersonOverAge,
+ as Parameterizable[Person, RequiredAgeInYears]
+ where {
+ my ($person, $required_years_old) = @_;
+ return $person->years_old > $required_years_old;
+ }
This would validate the following:
-
- my $person = Person->new(age=>35);
- PersonOverAge([18])->check($person);
-
+
+ my $person = Person->new(age=>35);
+ PersonOverAge([18])->check($person);
+
You can then apply the following coercion
- coerce PersonOverAge,
- from Dict[age=>int],
- via {Person->new(%$_)},
- from Int,
- via {Person->new(age=>$_)};
-
+ coerce PersonOverAge,
+ from Dict[age=>int],
+ via {Person->new(%$_)},
+ from Int,
+ via {Person->new(age=>$_)};
+
This coercion would then apply to all the following:
- PersonOverAge([18])->check(30); ## via the Int coercion
- PersonOverAge([18])->check({age=>50}); ## via the Dict coercion
+ PersonOverAge([18])->check(30); ## via the Int coercion
+ PersonOverAge([18])->check({age=>50}); ## via the Dict coercion
However, you are not allowed to place coercions on parameterizable types that have
had their constraining value filled, nor subtypes of such. For example:
- coerce PersonOverAge[18],
- from DateTime,
- via {$_->years};
-
+ coerce PersonOverAge[18],
+ from DateTime,
+ via {$_->years};
+
That would generate a hard exception. This is a limitation for now until I can
devise a smarter way to cache the generated type constraints. However, I doubt
it will be a significant limitation, since the general use case is supported.
Lastly, the constraining value is available in the coercion in much the same way
it is available to the constraint.
- ## Create a type constraint where a Person must be in the set
- subtype PersonInSet,
- as Parameterizable[Person, PersonSet],
- where {
- my ($person, $person_set) = @_;
- $person_set->find($person);
- }
-
- coerce PersonInSet,
- from HashRef,
- via {
- my ($hashref, $person_set) = @_;
- return $person_set->create($hash_ref);
- };
+ ## Create a type constraint where a Person must be in the set
+ subtype PersonInSet,
+ as Parameterizable[Person, PersonSet],
+ where {
+ my ($person, $person_set) = @_;
+ $person_set->find($person);
+ }
+
+ coerce PersonInSet,
+ from HashRef,
+ via {
+ my ($hashref, $person_set) = @_;
+ return $person_set->create($hash_ref);
+ };
=head2 Recursion
- TBD
+ TBD - Need more tests.
=head1 TYPE CONSTRAINTS
MooseX::Meta::TypeConstraint::Parameterizable->new(
name => 'MooseX::Types::Parameterizable::Parameterizable',
parent => find_type_constraint('Any'),
- constraint => sub {1},
+ constraint => sub {1},
)
);
projects / gitmo/MooseX-Dependent.git / blobdiff