=pod =head1 NAME UR::Object::Type - a meta-class for any class or primitive type =head1 SYNOPSIS use UR; class MyClass { is => ['ParentClass1', 'ParentClass2'], id_by => [ id_prop1 => { is => 'Integer' }, id_prop2 => { is => 'String' }, ], has => [ property_a => { is => 'String' } property_b => { is => 'Integer', is_optional => 1 }, ], }; my $meta = MyClass->__meta__; my @parent_class_metas = $meta->parents(); # 2 meta objects, see UR::Object::Property my @property_meta = $meta->properties(); # N properties (4, +1 from UR::Object, +? from ParentClass1 and ParentClass2) $meta->is_abstract; $meta->... =head1 DESCRIPTION UR::Object::Type implements the class behind the central metadata in the UR class framework. It contains methods for introspection and manipulation of related class data. A UR::Object::Type object describes UR::Object, and also every subclass of UR::Object. =head1 INHERITANCE In addition to describing UR::Object an each of its subclasses, UR::Object::Type is _itself_ a subclass of L. This means that the same query APIs used for regular objects can be used for meta objects. UR::Object -> has-meta -> UR::Object::Type A | \ / \-----<- is-a <-------/ Further, new classes which generate a new UR::Objec::Type, also generate a new subclass for the meta-class. This means that each new class can have private meta methods, (ala Ruby). This means that extensions to a meta-class, apply to the meta-class of its derivatives. Regular Meta-Class Entity Singleton ------- ---------- Greyhound has-meta -> Greyhound::Type | | V V is-a is-a | | V V Dog has-meta -> Dog::Type | | V V is-a is-a | | V V Animal has-meta -> Animal::Type | | V V is-a is-a | | /-----------------\ V V V | UR::Object has-meta -> UR::Object::Type has-meta -/ A is-a | | \______________________/ =head1 CONSTRUCTORS =over 4 =item "class" class MyClass1 {}; class MyClass2 { is => 'MyClass1' }; class MyClass3 { is => ['Parent1','Parent2'], is_abstract => 1, is_transient => 1, has => [ qw/p1 p2 p3/ ], doc => 'woo hoo!' }; The primary constructor is not a method on this class at all. UR catches "class SOMENAME { ... }" and calls define() with the parameters. =item define my $class_obj = UR::Object::Type->define( class_name => 'MyClass', ... ); Register a class with the system. The given class_name must be unique within the application. As a side effect, a new Perl namespace will be created for the class's name, and methods will be injected into that namespace for any of the class properties. Other types of metadata objects will get created to manage the properties and relationships to other classes. See the L documentation for more information about the parameters C accepts. =item create my $class_obj = UR::Object::Type->create( class_name => 'Namespace::MyClass', ... ); Create a brand new class within an already existing UR namespace. C takes all the same parameters as C. Another side effect of create is that when the application commits its Context, a new Perl module will be created to implement the class, complete with a class definition. Applications will not normally use create(). =back =head1 PROPERTIES Each property has a method of the same name =head2 External API =over 4 =item class_name $name = $class_obj->class_name The name of the class. Class names are unique within a UR namespace and an application. This is symmetrical with $class_obj = $name->__meta__. =item properties @all = $class_obj->properties(); @some = $class_obj->properties( 'is => ['Text','Number'] 'doc like' => '%important%', 'property_name like' => 'someprefix_%', ); Access the related property meta-objects for all properties of this class. It includes the properties of any parent classes which are inherited by this class. See L for details. =item property $property_meta = $class_obj->property('someproperty'); The singular version of the above. A single argument, as usual, is treated as the remainder of the ID, and will select a property by name. =item namespace $namespace_name = $class_obj->namespace Returns the name of the class's UR namespace. =item doc $doc = $class_obj->doc A place to put general class-specific notes. =item data_source_id $ds_id = $class_obj->data_source_id The name of the external data source behind this class. Classes without data sources cannot be saved and exist only during the life of the application. data_source_id will resolve to an L id. =item table_name $table_name = $class_object->table_name For classes with data sources, this is the name of the table within that data source. This is usually a table in a relational database. At a basic level, it is a storage directive interpreted by the data_source, and may or may not related to a storage table at that level. =item is_abstract $bool = $class_obj->is_abstract A flag indicating if this is an abstract class. Abstract classes cannot have instances, but can be inherited by other classes. =item is_final $bool = $class_obj->is_final A flag indicating if this class cannot have subclasses. =item is_singleton $bool = $class_obj->is_singleton A flag indicating whether this is a singleton class. If true, the class will inherit from L. =item is_transactional $bool = $class_obj->is_transactional A flag indicating whether changes to this class's instances will be tracked. Non-transactional objecs do not change when an in-memory transaction rolls back. It is similar to the is_transient meta-property, which does the same for an individual property. =back =head2 Internal API These methods return data about how this class relates to other classes. =over 4 =item namespace_meta $ns_meta = $class_obj->namespace_meta Returns the L object with the class's namespace name. =item parent_class_names @names = $class_obj->parent_class_names Returns a list of the immediate parent classes. =item parent_class_metas @class_objs = $class_obj->parent_class_metas Returns a list of the class objects (L instances) of the immediate parent classes =item ancestry_class_names @names = $class_obj->ancestry_class_names Returns a list of all the class names this class inherits from, directly or indirectly. This list may have duplicate names if there is multiple inheritance in the family tree. =item ancestry_class_metas @class_objs = $class_obj->ancestry_class_metas Returns a list of the class objects for each inherited class. =item direct_property_names @names = $class_obj->direct_property_names Returns a list of the property names defined within this class. This list will not include the names of any properties inherited from parent classes unless they have been overridden. =item direct_property_metas @property_objs = $class_obj->direct_property_metas Returns a list of the L objects for each direct property name. =item ancestry_property_names @names = $class_obj->ancestry_property_names Returns a list of property names of the parent classes and their inheritance hierarchy. The list may include duplicates if a property is overridden somewhere in the hierarchy. =item ancestry_property_metas @property_objs = $class_obj->ancestry_property_metas; Returns a list of the L objects for each ancestry property name. =item all_property_names Returns a list of property names of the given class and its inheritance hierarchy. The list may include duplicates if a property is overridden somewhere in the hierarchy. =item all_property_metas @property_objs = $class_obj->all_property_metas; Returns a list of the L objects for each name returned by all_property_names. =item direct_id_property_names @names = $class_obj->direct_id_property_names Returns a list of the property names designated as "id" properties in the class definition. =item direct_id_property_metas @property_objs = $class_obj->direct_id_property_metas Returns a list of the L objects for each id property name. =item ancestry_id_property_names =item ancestry_id_property_metas =item all_id_property_names =item all_id_property_metas @names = $class_obj->ancestry_id_property_names; @property_objs = $class_obj->ancestry_id_property_metas; @names = $class_obj->all_id_property_names; @property_objs = $class_obj->all_id_property_metas; Returns the property names or L objects for either the parent classes and their inheritance hierarchy, or for the given class and all of its inheritance hierarchy. The lists may include duplicates if properties are overridden somewhere in the hierarchy. =item unique_property_set_hashref $constraints = $class_obj->unique_property_set_hashref Return a hashref describing the unique constraints on the given class. The keys of $constraint are constraint names, and the values are listrefs of property names that make up the unique constraint. =item add_unique_constraint $class_obj->add_unique_constraint($constraint_name, @property_name_list) Add a unique constraint to the given class. It is an exception if the given $constraint_name already exists as a constraint on this class or its parent classes. =item remove_unique_constraint $class_obj->remove_unique_constraint($constraint_name) Remove a unique constraint from the given class. It is an exception if the given constraint name does not exist. =item ancestry_table_names =item all_table_names @names = $class_obj->ancestry_table_names Returns a list of table names in the class's inheritance hierarchy. =item direct_column_names Returns a list of column names for each direct property meta. Classes with data sources and table names will have properties with column names. =item direct_id_column_names Returns a list of ID column names for each direct property meta. =item direct_columnless_property_names =item direct_columnless_property_metas =item ancestry_columnless_property_names =item ancestry_columnless_property_metas =item all_columnless_property_names =item all_columnless_property_metas Return lists of property meta objects and their names for properties that have no column name. =back =head1 METHODS =over 4 =item property_meta_for_name $property_obj = $class_obj->property_meta_for_name($property_name); Return the L object in the class's inheritance hierarchy with the given name. If the property name has been overridden somewhere in the hierarchy, then it will return the property object most specific to the class. =item id_property_sorter $subref = $class_obj->id_property_sorter; @sorted_objs = sort $subref @unsorted_objs; Returns a subroutine reference that can be used to sort object instances of the class. The subref is able to handle classes with multiple ID properties, and mixes of numeric and non-numeric data and data types. =item autogenerate_new_object_id This method is called whenever new objects of the given class are created through Ccreate()>, and not all of their ID properties were specified. UR::Object::Type has an implementation used by default, but other classes can override this if they need special handling. =item singular_accessor_name_for_is_many_accessor $property_name = $class_obj->singular_accessor_name_for_is_many_accessor($is_many_name); For is_many properties, returns the name of the singular accessor. Usually, this the singular version of the plural, is_many property's name. The singular accessor accepts key/value pairs as arguments, which are used to filter the results of the is_many accessor. For example, the singular for the 'cars' accessor is 'car'. Returns a false value if the given property name does not exist or is not is_many. =item iterator_accessor_name_for_is_many_accessor $iter_name = $class_obj->iterator_accessor_name_for_is_many_accessor($is_many_name); Returns the accessor name used to get the L that corresponds with the is_many accessor. For example, the iterator for the 'cars' accessor is 'car_iterator'. Returns a false value if the given property name does not exist or is not is_many. =item set_accessor_name_for_is_many_accessor $set_name = $class_obj->set_accessor_name_for_is_many_accessor($is_many_name); Returns the accessor name used to get the L that corresponds with the is_many accessor. For example, the set for the 'cars' accessor is 'car_set'. Returns a false value if the given property name does not exist or is not is_many. =item rule_accessor_name_for_is_many_accessor $rule_name = $class_obj->rule_accessor_name_for_is_many_accessor($is_many_name); Returns the accessor name used to get the L that corresponds with the is_many accessor. For example, the rule for the 'cars' accessor is '__car_rule'. Returns a false value if the given property name does not exist or is not is_many. =item arrayref_accessor_name_for_is_many_accessor $arrayref_name = $class_obj->arrayref_accessor_name_for_is_many_accessor($is_many_name); Returns the accessor name used to get the arrayref of objects that corresponds with the is_many accessor. For example, the arrayref for the 'cars' accessor is 'car_arrayref'. Returns a false value if the given property name does not exist or is not is_many. =item adder_name_for_is_many_accessor $adder_name = $class_obj->adder_name_for_is_many_accessor($is_many_name); Returns the method name used to get the adder method that corresponds with the is_many accessor. For example, the adder for the 'cars' accessor is 'add_car'. Returns a false value if the given property name does not exist or is not is_many. =item remover_name_for_is_many_accessor $remover_name = $class_obj->remover_name_for_is_many_accessor($is_many_name); Returns the method name used to get the remover method that corresponds with the is_many accessor. For example, the adder for the 'cars' accessor is 'remove_car'. Returns a false value if the given property name does not exist or is not is_many. =back =head1 SEE ALSO L, L, L, L =cut