Seem to be having a slight problem

class CObject; typedef std::list<CObject>::iterator ObjectPointer; ... std::vector<CObject> CObject::Objects; ... const ObjectPointer CObject::New(void) { Objects.resize(Objects.size() + 1); ObjectPointer NewObject = Objects.end()-1; <<<<<<<<<<< return NewObject; }

No constructor could take the source type, or constructor overload resolution was ambiguous Can anyone see something wrong with that line that I can''t? Thanks Chris

// Use a global list object or a store a list memeber in a classstd::list<CObject> m_vObjects;// Then create a temporary objectCObject ob;ob.member1 = 5;ob.member2 = 15;// And push back into your real listm_vObjects.push_back(ob);

Zeblar Nagrim, Lord of Chaos

Your problem is that your "pointer" is a list iterator, and your collection is a vector. These are two diffent types completely. You can''t convert between two iterators of different types of containers.

The first thing you need to decide is what container you really want--list or vector? According to your function, which seems to allocate a new object from a global store of objects, you should probably use a list.

If what you''re trying to do in the class is return an iterator to the last object, you need to do this:
ObjectPointer NewObject = Objects.end ();
return --NewObject;

The reason is that your function tries to do a random access jump by subtracting 1. You can only do iterator+N (i.e. it-1) with random access iterators, and the only things that give you that are vectors and dequeues. A list gives you a bidirectional iterator, so you are allowed to do ++it and --it (but never it-1).

That''s how to make it compile, but it won''t work very well. Your container is one of CObject, not CObject*. If you are hoping to make CObject a base class and store derived objects, you won''t be able to do it. If you wanted a polymorphic container, you must use CObject*.

Since you''re returning a const iterator, you''ll only be able to use the const methods of the iterator, which means only dereferencing a const CObject (I believe, should probably check this), which means you won''t be able to call any non-const methods of CObject.

If your intention was only to not let the client iterate over the list, why not do this instead?

CObject &CObject::New (){ // insert default object at end & return reference to it return *Objects.insert (Objects.end ());}

One-liner, good for inlining if you''ll be doing it a lot. Returns reference to the newly inserted object, not a copy of the object (which would be expensive).

Good luck.

Ack!

I''d say more than 50% of my code errors are from thoughless cut ''n paste''s.

Thanks for all the other info, I didn''t even consider the consequences of a const iterator.

Thanks again stoffel...


Zeblar : I tend to go with static databases with static New members as it hides the implementation from the clients. That way I can change the database shape (say vector\list) without touching client code. I''ve only just started using iterators yesterday, using the subscript elements until now has worked fine.

Thanks all,

Chris