Pure CppWinRT Out-Of-Proc COM Server without WRL Demo

Features

1. Automatic shutdown
2. WinRT-as-COM Server registration based on variadic template instead of marcro
3. No WRL (rightfully so)

Quick Start

1. Open solution in VS
2. Launch Server. It should stay opened
3. Launch client while server is running by right-clicking client project -> Debug -> Start new instance
4. Observe server shuts down

Motivation

There has been ask for out-of-proc, non-DLL COM server support with pure cppwinrt for a long time. The above screenshot comes from microsoft/cppwinrt#601. Many people expressed interest, but that thread went nowhere.

Expectedly, cppwinrt wants to maintain its focus on only projection/consumption/authoring. IMO that is a good call. But that doesn't change the fact that this ask is left unfulfiled. And people always have to go back to WRL as it just works™️.

This sample demonstrates how with simple additions, out of proc cppwinrt COM server without WRL is possible.

This sample has two goals:

1. Make these classes into WIL (Windows Implementation Library). The API might need some tweak but the concept works.
2. Update all IExploerCommand and IWidgetProvider sample to use only cppwinrt + WIL instead of WRL. Let WRL stay in the past.

Subsequently, I hope that powertoys etc would pick up the momentum and migrate to cppwinrt + WIL for its IExplorerCommand context menu implementation.

How it works

1. cppwinrt expose a configuration WINRT_CUSTOM_MODULE_LOCK that allows users to hook into the module lock mechanism
2. Write a custom module lock which, (a) notifies when module count reaches 0, and (b) provides customization point for the notification
3. cppwinrt also provides winrt::no_module_lock so that class factory implementation can be omitted from module object count
4. Write variadic functions that take in authored type and register class factory recursively