Why is Abi hidden in the docs?

[estokes]

I'm a somewhat new user of this crate, and I've just finished using it to build an RTD server for Excel. One major thing that tripped me up during that process is that I had to extract the IDispatch interface for a callback object from a VARIANT that Excel passed me (the IRTDUpdateEvent object). In the union type of VARIANT_0_0_0 it's a RawPointer, and it took me quite a while, and a trip to the source code, to figure out that I needed to call Com::IDispatch::from_abi(ptr) in order to get a proper IDispatch interface from this RawPointer. So I guess I have two questions.

• Am I doing something wrong? It does work, but maybe that's luck and I'm missing something huge. If I'm doing it wrong, then how am I supposed to get an IDispatch from a VARIANT?
• If I'm not doing it wrong, then why hide from me that IDispatch implements Abi? If there is some good reason it must remain hidden, then maybe a helper function in VARIANT_0_0_0 that gets an IDispatch directly instead of a RawPointer?

[kennykerr]

The Abi trait is hidden as it is a low-level implementation detail needed for certain generic scenarios within the windows crate but should not be used directly. It's little more than a transmute though and I'd suggest you simply transmute yourself if you're casting from a pointer. The VARIANT struct is very difficult to use directly and really needs a hand-written wrapper. #539

[estokes]

Casting the pointer, my initial solution, caused a crash. I guess I need to read exactly what abi does in the case of an interface and figure out what it does differently.

[estokes]

In any case if you're planning to build a wrapper for VARIANT that solves my issue. Thanks!