A Note on the RWFactory
The RWDEFINITION_MACROs can appear as the following:
RW_DEFINE_COLLECTABLE_CLASS_BY_ID(USER_MODULE, className, numericID)
or, using a string ID:
RW_DEFINE_COLLECTABLE_CLASS_BY_NAME(USER_MODULE, className, stringID)
In the .cpp file for the bus example, the macros appear like this:
RW_DEFINE_COLLECTABLE_CLASS_BY_ID(USER_MODULE, Bus, 200)
and:
RW_DEFINE_COLLECTABLE_CLASS_BY_NAME(USER_MODULE, Client, "a client")
Because you use these macros, a program can allow a new instance of your class to be created given only its RWClassID:
Bus* newBus = (Bus*)theFactory->create(200);
or its RWStringID:
Client* aClient = (Client*)theFactory->create("a client");
The pointer
theFactory is a global pointer that points to a one-of-a-kind global instance of class
RWFactory, used to hold information about all
RWCollectable classes that have instances in the executable. The
create() method of
RWFactory is used internally by the polymorphic persistence machinery to create a new instance of a persisted object whose type is not known at run time. You will not normally use this capability in your own source code, because the use of
RWFactory is generally transparent to the user. See the
../sourceproref:index.htmlSourcePro C++ API Reference Guide for more details on
RWFactory.