Identifier

Description

The Identifier is a construct to identify the class of an object. All classes derived from OrxonoxClass have an Identifier, representing the class in the running game. The Identifier additionally stores all objects of its class in a list, knows the name of the class, can have a ClassFactory, knows all parents and children, stores config-values and shell-functions and provides several other functionalities.

You can get the Identifier of a given class with the macro Class(classname). If you only know the string, so if the class isn't hardcoded, use the macro ID("classname"). You have to include CoreIncludes.h to use the macros.

A new class that wants an Identifier must use a macro (RegisterObject(classname) or RegisterRootObject(interfacename)) from CoreIncludes. Read the related Wiki-page for more informations.

Identifiers can be compared by using functions like isA(…) or isChildOf(…) to retrieve informations about the class-hierarchy.

You can't create an Identifier directly, because it's an abstract class. There only exist ClassIdentifiers, but you can't create them too, because they have private constructors. Identifiers are created by IdentifierDistributor?, a helper class to warrant the uniqueness of an Identifier for a class.

The SubclassIdentifier is a class, that can store and act like an Identifier, but has a given base-class. Read the related Wiki-page for more informations.

Functions

• Macro: (Include CoreIncludes.h to use this)
  • Identifier* myidentifier = Class(BaseObject);
  • Identifier* myidentifier = ID("BaseObject");

• Comparison:
  • myidentifier→isA(other): Compares the Identifier (myidentifier) with another Identifier (other). If myidentifier represents exactly the same or an inheriting class, the function returns true.
  • myidentifier→isExactlyA(other): If myidentifier and other represent both the same class, the function returns true.
  • myidentifier→isChildOf(other): If the class represented by myidentifier is a child of the class represented by other, the function returns true.
  • myidentifier→isDirectChildOf(other): Like isChildOf(…), but the class represented by myidentifier must be inherited directly without other classes between (class myidentifierclass : public otherclass).
  • myidentifier→isParentOf(other): If the class represented by myidentifier is a parent of the class represented by other, meaning the other class is a child, the function returns true.
  • myidentifier→isDirectParentOf(other): Like isParentOf(…), but the class represented by myidentifier must be a direct parent without other classes between (class otherclass : public myidentifierclass).

• Fabricate:
  • fabricate() returns a new object of the class represented by the Identifier (see ClassFactory).

• Name:
  • getName() returns the name of the represented class.

• Class-hierarchy: You can retrieve lists and iterators (begin and end) of:
  • parents: getParents(), getParentsBegin(), getParentsEnd()
  • directParents: getDirectParents(), getDirectParentsBegin(), getDirectParentsEnd()
  • children: getChildren(), getChildrenBegin(), getChildrenEnd()
  • directChildren: getDirectChildren(), getDirectChildrenBegin(), getDirectChildrenEnd()

Examples

The following examples use the class-tree below.

Identifier* myidentifier = Class(A1);            // Assigns the Identifier of A1

myidentifier->isA(Class(BaseObject));            // returns true
myidentifier->isA(Class(A1));                    // returns true
myidentifier->isA(Class(A1B1));                  // returns false
myidentifier->isA(Class(A2));                    // returns false
Class(A3)->isA(Class(Interface1));               // returns true

Class(A1B1)->isChildOf(Class(BaseObject));       // returns true
Class(A1B1)->isChildOf(Class(A1));               // returns true

Class(A1B1)->isDirectChildOf(Class(BaseObject)); // returns false
Class(A1B1)->isDirectChildOf(Class(A1));         // returns true

// Assigns the Identifier of the class with name "A2"
std::string name = "A2";
Identifier* other = ID(name);

// Creates a new instance of A1
BaseObject* newobject = Class(A1)->fabricate();

// Creates a new instance of A1 and casts it to Interface1
Identifier* myidentifier = Class(A3);
Interface1* newobject = (Interface1)(myidentifier->fabricate());

Identifier* myidentifier = Class(BaseObject);
for (std::list<const Identifier*>::const_iterator it = myidentifier->getDirectChildrenBegin(); it != myidentifier->getDirectChildrenEnd(); ++it)
  cout << (*it)->getName() << std::endl;

/*
returns all direct children of BaseObject:
A1
A2
A3
*/

Networking

Because Identifiers use pointers, they are not qualified for networking. It's possible to just send the classname and use the Factory, but this is expensive. That's why there's a network ID.

The network ID is an unsigned integer. You can retrieve an Identifier with a given network ID by using the macro ID(int) (include CoreIncludes.h to use it). It's not determined which network ID belongs to which Identifier. This changes from version to version and from system to system, depending on the number of existing classes and the code executed before main(). So ID(5) might be different on each client. That's why the server has to synchronize the network ID's.

You can retrieve the network ID of an Identifier with getNetworkID().
You can set the network ID of an Identifier with setNetworkID(int).

After changing the network ID of an Identifier to newid, there might be two Identifiers with the ID newid. ID(newid) will then return the changed Identifier and not the old one.

Read the Wiki-page of Factory to get more informations about how to iterate through all Identifiers.

Technical informations

—-to come—-