Interface
Implementations of this interface are objects and MUST provide the following methods:
-
$constraint->check($value) -
Checks that the value meets the constraint. Under normal operation should return true or false to indicate a pass or failure.
Exceptions should not be thrown when a value simply fails the constraint, but may be used for other exceptional conditions. (For example, if the check requires a database lookup to determine pass or failure, but the database is unavailable.)
-
$constraint->get_message($value) -
Generates an message explaining that the value has failed the type constraint, and returns this messages as a string. This method does not need to check whether the value genuinely fails the constraint; it can assume that the check method has already been called.
Implementations
MAY
advertise that they support this interface by returning true for
$constraint->DOES("Type::API::Constraint")
.
See Also
Implementations
The following CPAN classes are known to implement Type::API::Constraint:
- Moose::Meta::TypeConstraint (and its subclasses)
- MooseX::Meta::TypeDecorator
- Mouse::Meta::TypeConstraint
- MouseX::Meta::TypeDecorator
- Specio::Constraint::Simple (and several other classes in the Specio distribution)
- Type::Tiny (and its subclasses)
Consumers
Some tools can make use of objects implementing Type::API::Constraint:
- Data::Validator
- "Experimental experimental feature: Type expressions" in Function::Parameters
- Scalar::Does
- Type::Tie
Others, such as Moose and Mouse require type constraints that implement a superset of this functionality.