RWFactory

Module:  Essential Tools Module   Group:  RWCollectable Classes

RWFactoryRWSet

• Local Index
• Synopsis
• Description
• Persistence
• Example
• Public Constructors
• Public Destructor
• Public Operator
• Public Member Functions

Members

addFunction() classID() create()

getFunction() operator<=() removeFunction()

RWFactory() stringID() ~RWFactory()

typedef unsigned short  RWClassID;
typedef RWCollectable*  (*RWuserCreator)();
#include <rw/factory.h>
RWFactory* theFactory;

Class RWFactory can create an instance of an RWCollectable object, given a class ID. It does this by maintaining a table of class IDs and associated "creator functions." A creator function has prototype:

RWCollectable*  aCreatorFunction();

This function should create an instance of a particular class. For a given RWClassID tag, the appropriate function is selected, invoked and the resultant pointer returned. Because any object created this way is created off the heap, you are responsible for deleting it when done.

There is a one-of-a-kind global RWFactory which can be accessed using getRWFactory(). It is guaranteed to have creator functions in it for all of the classes referenced by your program. See also the section in the User's Guide about RWFactory.

None

#include <iostream>

#include <rw/tools/ctdatetime.h>
#include <rw/factory.h>
#include <rw/rwbag.h>

int main ()
{
    std::cout << "This program creates an RWBag using theFactory.\n";

    // Dummy access to RWBag interface to stimulate 
    // the registration of RWBag with the factory.
    RWBag ().clear ();

    // Create the RWBag instance - use the special rwCreateFromFactory.
    RWBag* ptr = (RWBag*)(rwCreateFromFactory (__RWBAG));
    if (0 == ptr) {
        std::cout << "RWBag instance creation failed.\n";
        return 1;
    }

    std::cout << "RWBag instance has been created.\n";

    // Insert today's date
    ptr->insert (new RWCollectableDateTime (RWCollectableDateTime::setCurrentTime));
    std::cout << "RWBag instance contains an instance of RWCollectableDateTime.\n";

    // First delete members ...
    ptr->clearAndDestroy();                 
    std::cout << "RWBag instance content cleared.\n";
 
    // ... then the bag itself.
    delete ptr;
    std::cout << "RWBag instance deleted.\n";

    return 0;
}

Program output:

This program creates an RWBag using theFactory.
RWBag instance has been created.
RWBag instance contains an instance of RWCollectableDateTime.
RWBag instance content cleared.
RWBag instance deleted.

RWFactory();

Construct an RWFactory.

~RWFactory();

Calls clearAndDestroy(), which is inherited from RWSet.

bool
operator<=(const RWFactory& h);

Returns true if self is a subset of h, that is, every element of self has a counterpart in h which isEqual. This operator is included to fix an inconsistency in the C++ language. It is not explicitly present unless you are compiling with an implementation of the C++ Standard Library. It would normally be inherited from RWSet.

Note: If you inherit from RWFactory in the presence of the C++ Standard Library, we recommend that you override this operator and explicitly forward the call. Overload resolution in C++ will choose the standard library provided global operators over inherited class members. These global definitions are not appropriate for set-like partial orderings.

void
addFunction(RWuserCreator uc, RWClassID id);

Adds to the RWFactory the global function pointed to by uc, which creates an instance of an object with RWClassID id.

void
addFunction(RWuserCreator uc, RWClassID id,RWStringID sid);

Adds to the RWFactory the global function pointed to by uc, which creates an instance of an object with RWClassID id and RWStringID sid.

RWClassID
classID(RWStringID) const;

Looks up the RWClassID associated with sid and returns it. If there is no such association, returns __RWUNKNOWN.

RWCollectable*
create(RWClassID id) const;

Allocates a new instance of the class with RWClassID id off the heap and returns a pointer to it. Returns nil if id does not exist. Because this instance is allocated off the heap, you are responsible for deleting it when done.

RWCollectable*
create(RWString sid) const;

Allocates a new instance of the class with RWStringID sid off the heap and returns a pointer to it. Returns nil if sid does not exist. Because this instance is allocated off the heap, you are responsible for deleting it when done.

RWuserCreator
getFunction(RWClassID id) const;

Returns from the RWFactory a pointer to the global function associated with RWClassID id. Returns nil if id does not exist.

RWuserCreator
getFunction(RWStringID sid) const;

Returns from the RWFactory a pointer to the global function associated with RWStringID sid. Returns nil if sid does not exist.

void
removeFunction(RWClassID id);

Removes from the RWFactory the global function associated with RWClassID id. If id does not exist in the factory, no action is taken.

void
removeFunction(RWStringID sid);

Removes from the RWFactory the global function associated with RWStringID sid. If sid does not exist in the factory, no action is taken.

RWStringID
stringID(RWClassID id) const;

Looks up the RWStringID associated with id and returns it. If there is no such association, returns RWStringID("NoID").

© Copyright Rogue Wave Software, Inc. All Rights Reserved.
Rogue Wave and SourcePro are registered trademarks of Rogue Wave Software, Inc. in the United States and other countries. All other trademarks are the property of their respective owners.
Contact Rogue Wave about documentation or support issues.