Circular Includes

slypete

Hello,

Is it possible to use the IceUtil::Handle smart pointer class for circular includes? I cannot seem to figure it out without getting a billion errors. If I use a forward declaration and then declare a smart pointer of that class in my interface, I obviously cannot since it's simply a template class and it will try to instantiate the unknown class in the header. I can probably store a pointer to the smart pointer, but I haven't tried it because that just seems very wrong.

For now as a work around, I just look up what room the player is in each time the player makes a request that requires a room. You can see that I'd much rather just store a smart pointer to the room the player is in.

I'm sure that I'm just misusing something. Can you please shed some light down on me?

Thanks a lot,
Pete

bernard

Hi Pete,

You cannot use IceUtil::Handle for circular includes, as the IceUtil::Handle needs to see the declaration of the class parameter.

If you're adventurous, you could use IceInternal::Handle, which is very similar to IceUtil::Handle but supports such cyclic includes. From Ice/Handle.h:

//
// "Handle" or "smart pointer" class for classes derived from
// IceUtil::GCShared, IceUtil::Shared, or IceUtil::SimpleShared.
//
// In constrast to IceUtil::Handle, IceInternal::Handle requires the
// declaration of the two global operations IceInternal::incRef(T*)
// and IceInternal::decRef(T*). The use of global operations allows
// this template to be used for types which are declared but not
// defined, provided that the two above mentioned operations are
// declared.
//

IceInternal::Handle is also compatible with IceUtil::Handle. However, like any IceInternal type, it's undocumented and can change at anytime.

Cheers,
Bernard

bernard

Hi Pete,

I should have double-checked this comment before copying it here , as it doesn't match the code. IceInternal::Handle needs now a single function, upCast, that upcasts a pointer to the template parameter to an IceUtil::Shared*.

Cheers,
Bernard

slypete

Thanks Bernard!

This is very useful information, and I doubt that I would have come across it myself. I'm surprised ZeroC doesn't offer this class in the public API. It surely must come up often?

Thanks again,
Pete