--- name: "UR::Object::Type" section: "3pm" platform: "linux" package: "libur-perl" version: "0.470+ds-3" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/UR::Object::Type" --- # UR::Object::Type(3pm) a meta-class for any class or primitive type ## NAME UR::Object::Type - a meta-class for any class or primitive type ## 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->... ``` ## 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. ## INHERITANCE In addition to describing UR::Object an each of its subclasses, UR::Object::Type is \_itself\_ a subclass of UR::Object. 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 | | \______________________/ ``` ## CONSTRUCTORS - "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. - 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 UR::Object::Type::Initializer documentation for more information about the parameters `define()` accepts. - create ``` my $class_obj = UR::Object::Type->create( class_name => 'Namespace::MyClass', ... ); ``` Create a brand new class within an already existing UR namespace. `create()` takes all the same parameters as `define()`. 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()**. ## PROPERTIES Each property has a method of the same name ### External API - 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\_\_. - 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 UR::Object::Property for details. - 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. - namespace ``` $namespace_name = $class_obj->namespace ``` Returns the name of the class's UR namespace. - doc ``` $doc = $class_obj->doc ``` A place to put general class-specific notes. - 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 UR::DataSource id. - 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. - 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. - is\_final ``` $bool = $class_obj->is_final ``` A flag indicating if this class cannot have subclasses. - is\_singleton ``` $bool = $class_obj->is_singleton ``` A flag indicating whether this is a singleton class. If true, the class will inherit from UR::Singleton. - 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. ### Internal API These methods return data about how this class relates to other classes. - namespace\_meta ``` $ns_meta = $class_obj->namespace_meta ``` Returns the UR::Namespace object with the class's namespace name. - parent\_class\_names ``` @names = $class_obj->parent_class_names ``` Returns a list of the immediate parent classes. - parent\_class\_metas ``` @class_objs = $class_obj->parent_class_metas ``` Returns a list of the class objects (UR::Object::Type instances) of the immediate parent classes - 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. - ancestry\_class\_metas ``` @class_objs = $class_obj->ancestry_class_metas ``` Returns a list of the class objects for each inherited class. - 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. - direct\_property\_metas ``` @property_objs = $class_obj->direct_property_metas ``` Returns a list of the UR::Object::Property objects for each direct property name. - 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. - ancestry\_property\_metas ``` @property_objs = $class_obj->ancestry_property_metas; ``` Returns a list of the UR::Object::Property objects for each ancestry property name. - 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. - all\_property\_metas ``` @property_objs = $class_obj->all_property_metas; ``` Returns a list of the UR::Object::Property objects for each name returned by all\_property\_names. - 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. - direct\_id\_property\_metas ``` @property_objs = $class_obj->direct_id_property_metas ``` Returns a list of the UR::Object::Property objects for each id property name. - ancestry\_id\_property\_names - ancestry\_id\_property\_metas - all\_id\_property\_names - 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 UR::Object::Property 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. - 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. - 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. - 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. - ancestry\_table\_names - all\_table\_names ``` @names = $class_obj->ancestry_table_names ``` Returns a list of table names in the class's inheritance hierarchy. - 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. - direct\_id\_column\_names Returns a list of ID column names for each direct property meta. - direct\_columnless\_property\_names - direct\_columnless\_property\_metas - ancestry\_columnless\_property\_names - ancestry\_columnless\_property\_metas - all\_columnless\_property\_names - all\_columnless\_property\_metas Return lists of property meta objects and their names for properties that have no column name. ## METHODS - property\_meta\_for\_name ``` $property_obj = $class_obj->property_meta_for_name($property_name); ``` Return the UR::Object::Property 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. - 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. - autogenerate\_new\_object\_id This method is called whenever new objects of the given class are created through `"ClassName->create()"`, 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. - 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. - 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 UR::Object::Iterator 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. - 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 UR::Object::Set 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. - 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 UR::BoolExpr 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. - 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. - 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. - 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. ## SEE ALSO UR::Object::Property, UR::Object::Iterator, UR::Object::Set, UR::BoolExpr