what keeps a COM object alive?

[Sean Cavanaugh]

On 6/11/2013 10:38 PM, finalpatch wrote:
> A typical COM server would create a new object (derived from IUnknown),
> return it to the caller (potentially written in other languages).
> Because the object pointer now resides outside of D's managed heap, does
> that mean the object will be destroyed when the GC runs? A normal COM
> object written in C++ relies on reference counting to manage its life
> cycle but in D the ref counting seems not serving any purpose. The
> AddRef()/Release() of std.c.windows.com.ComObject maintains a ref count,
> but doesn't really use it for any thing. There's a comment in Release()
> says "let the GC reap it", but how does the GC know the object is okay
> to destroy?

COM is by definition ref counted.  In D you generally need to store a 
COM pointer in a struct and maintain the refcount with that struct 
(increment on copy, decrement in destructor, etc).  Its not too hard, as 
'alias this' usage can wrap the pointer's methods easily enough.