Syntax for Pointer to Class

[Q. Schroll]

On Friday, 25 January 2019 at 20:31:29 UTC, H. S. Teoh wrote:
> On Fri, Jan 25, 2019 at 08:12:33PM +0000, Q. Schroll via 
> Digitalmars-d-learn wrote:
>> Say I have a class C and I want a pointer to a C handle.
>
> Note that taking the address of `C` will actually give you a 
> pointer to the reference, not the pointer to the class instance 
> itself.

I know. This is precisely the thing I asked for: A pointer to a 
handle. I called it handle for exactly this reason.

> For that to be valid, you'll need to store your class reference 
> somewhere first, since it's invalid to take the address of an 
> rvalue

Yes. `&new C(...)` looked to wrong for me to even consider trying.

> 	C c = new C(...);
> 	C* ptrToRef = &c;

So the answer is no. At least not that simple.

> Be warned that the pointer will become invalid when the 
> reference `c` goes out of scope, even if the object itself is 
> still live (via another reference), because the pointer is 
> pointing to the class reference rather than the actual object.

That's kind of obvious if you get remembered, but thanks. I 
wasn't considering this as I wanted the handle to live on the 
heap anyway --- the same way for a struct `S`, the pointer 
pointed to by `S** ptr = new S*(new S(...));` lies on the heap.

I'll use

     C* ptr = &[ new C(...) ][0];

for now. It looks ugly, but it does the job.