Changes between Initial Version and Version 1 of code/howto/Identifier

Timestamp:

Oct 10, 2008, 1:37:07 AM (17 years ago)

Author:

landauf

Comment:

—

code/howto/Identifier

@@ +1 @@
+= HowTo: Identifiers =
+[[TracNav(TracNav/TOC_Development)]]
+[[TOC]]
+
+== Description ==
+'''Important''': Identifiers are only available to classes in the class hierarchy. Read [wiki:howto/ClassHierarchy this] for more information.
+
+The Identifier is a construct used to identify a class at runtime. It is also a container for several class-related stuff, but this is not topic of this page. Read [wiki:Identifier this] for more detailed information.
+
+This page explains how to work with Identifiers.
+
+== Get the Identifier of a class ==
+To get the Identifier belonging to a class, just use '''Class('''''ClassName''''')''':
+{{{
+Identifier* identifier = Class(MyClass);
+}}}
+
+It's also possible to get the Identifier of a class by using a string:
+{{{
+Identifier* identifier = ClassByString("MyClass");
+}}}
+
+== Get the Identifier of an object ==
+If you want to know to which class an object belongs, just use '''getIdentifer()''':
+
+{{{
+BaseObject* object = getSomeObject();
+
+Identifer* identifier = object->getIdentifier();
+}}}
+
+Now how do you get information about this class? For example the name? Just call '''getName()''' on the Identifier:
+{{{
+std::cout << "The object is a " << identifier->getName() << std::endl;
+}}}
+
+The output of this code might be: "The object is a WorldEntity".
+
+== Compare classes ==
+If you want to know if an object is an instance of a class inheriting from a given class (or it's the class itself), use '''isA('''''identifier''''')''':
+{{{
+BaseObject* object = getSomeObject();
+
+bool isAMyClass = object->getIdentifier()->isA(Class(MyClass));
+
+if (isAMyClass)
+    std::cout << "Object is a MyClass!" << std::endl;
+}}}
+
+You can do this even shorter:
+{{{
+object->isA(Class(MyClass));
+}}}
+
+Apart from isA(...), there are other comparision functions:
+ * isExactlyA
+ * isChildOf
+ * isDirectChildOf
+ * isParentOf
+ * isDirectParentOf
+
+Read [wiki:Identifier#Comparison this] for more information.
+