determining if a void* points to a valid Object

[Luís Marques]

Sean Kelly wrote:
> It would be a horrible hack, but you might be able to test whether the 
> location reserved for the vtbl ptr points to a location where vtbls are 
> known to reside.  The ABI might be of help here: 
> http://www.digitalmars.com/d/abi.html  You will have to ask Walter or do 
> some sleuthing to sort out how to determine this address range, however.

http://www.digitalmars.com/d/abi.html tells us:

An object consists of:

offset 	contents
0       pointer to vtable
4       monitor
8... 	non-static members

So if the NotDObject struct was defined as { void *isobject = null; ... 
} then we could look at isobject and if was not null it would be a D 
Object. Or can a D Object not have a vtable? That is, could the "pointer 
to vtable" be null? Even if that was the case I could add dummy virtual 
methods to my classes...

Btw: I guess this ABI is 32 bit only :/

Thanks Sean!

Luís