Ok so I have a blank class p class p{}; then a couple of classes such as class x : public p { void func1() }; class y : public p { void func2() }; So in code I define a pointer type p p *myP; ...In the hope that at run time I can create an X or Y such as if(casey==1) myP = new x; else mpP = new y; ok, so then how do I access members of x or y without using virtual functions in p? Because the following sure dont work. myP->func2(); How might I do this? The problem is that I'm using a blank base class, as my derived classes have nothing in common that I could make virtual. Thanks DaveC

yes :), that's a very good point.

But I was trying to create a list of unrelated classes. I know this is probably not a good idea. What would you suggest?

if you could describe the application a bit more, im sure one of the bright cookies around here will be able to give you an ideal answer [wink]

Cheers
-Danu

Really, your best solution is not creating a list of unrelated classes [smile].

Basically, if they have nothing in common, then they shouldn't be in the same inheritance hirachy, and thusly you shouldn't be creating lists of totally unrelated classes. The best solution probably is to use several lists.


Alternitivly, if all they have in common is that they must go into the list together (which is highly unusual and you should rethink your design), inheriting (or multiple-inheriting) from the "p" class you have there is probably the best solution.

Then what you probably want to look at is the dynamic_cast operator. [edit: SiCrane beat me to it - and as he says - virtual destructor may be necessary]

Ok, thanks for that.. here is a little more information.

I’m creating an asset management system, something I though would be simple at first. So I have a base class asset that is blank then I have other classes such as Texture, Mesh, Object and so on that inherit this.

Class Casset {// nothing here};
Class Ctexture : public asset { // texture stuff };
Class Cmesh : public asset { // mesh stuff };
Class Cobject : public asset { // object stuff };

I have an asset management class that checks if the asset is loaded, maintains the list of assets, returns pointers to the assets and so on. Also a Node class that forms the linked list used by the asset management class.

Class CNode
{
Casset *TheAsset;
CNode *NextNode;
int AssetID;
// all the usual linked list stuff
};

Class CAsset_Manager
{
CNode *FirstNode
Casset findAsset(int assetID);
// all the usual linked list stuff
};

The findAsset function searched all the Nodes for the assetID, if it does not exist then it gets created and added to the list.

I’ve left out a lot of code here, but I had the Asset_Manager working and all the classes were being created correctly, and destroyed. I just had not though far enough ahead to where I actually needed to access the Assets member functions.

Because the Mesh class has completely different structure to that of a Texture class.

My hope was (again without thinking about it) that I could do this.

New Casset tasset = AssetManager.findAsset(1);
tasset->”some texture member function if this is a texture”;
// does not work because Casset has no member function.

or

New Ctexture tTexture = AssetManager.findAsset(1);
tTexture->”some texture member function if this is a texture”;
// does not work because findAsset returns a Casset

hmm?