Making an agile version of a Windows Runtime delegate in C++/WinRT, part 3 - The Old New Thing

14 hours ago

RoGetAgileReference fails for objects implementing INoMarshal, causing CO_E_NOT_SUPPORTED exceptions even if marshaling is unnecessary.
A wrapper delegate is created that checks if the invocation context matches the original context; if so, it calls the delegate directly, otherwise throws the exception.
The implementation captures the original context using IContextCallback and compares it at invoke time.
Using a universal reference (Delegate&&) allows moving the delegate when passed as an rvalue, improving performance.
The first try is presented with a note that a further optimization will be discussed next time.

Hasty Briefsbeta