> work nicely with win32 is probably less effort

Gonna be very hard to do. For the last 15+ years COM is essential part of WinAPI, and too many things in Rust conflict with COM: ownership, OOP, virtual tables, inheritance, they all too different.

Not just in Rust, in all languages, actually. You only have 2 good choices for complex platform-dependent windows development: either C++, or a microsoft's language with COM support embedded deep in the runtime, like VB6 or VBScript or .NET.

> too many things in Rust conflict with COM

Do they? COM in its essence defines two things:

1. A binary ABI for interoperability of components written in whatever language. 2. Reference-counting mechanism and "casting" mechanism (IUnknown).

MS has an article that shows how to build a COM component from the ground-up using only plain C structs containing function pointers (which is how vtables are implemented anyway: array of function pointers). What you think of inheritance can be implemented with a struct containing nested structs of function pointers. Etc.

It's not insurmountable, e.g., PyWin32 has utilities for both consuming and implementing COM components.

> COM in its essence defines two things

COM is quite a lot of things. Also threading model, date-time-currency formats, late binding/dynamic dispatch/scripting, type info both runtime and design time, IPC, RPC, security, and more.

> What you think of inheritance can be implemented with a struct containing nested structs of function pointers

What I think of inheritance in the context of COM is called “aggregation” and it’s more complex than that.

> It's not insurmountable

It’s not, but you’ll spend ~2x more time doing that compared to C++, and ~4x more time compared to VBScript or .NET.

Update: that 2x-4x is for implementation. For consumption C++ and .NET are close, but anything else is more complex due to FFI in between. C++ or VBScript don’t need FFI, .NET runtime is designed around many key parts of COM e.g. they have reused HRESULT’s and type info format.

Delphi, JavaScript, Python and C++ Builder as well.

I think Delphi and C++ Builder were only good enough while WinAPI meant “C API”.

JavaScript is OK for platform-independent development with electron. For platform-specific i.e. WinRT not that good, .NET is just better, and MS put the JS libraries in maintenance mode: https://github.com/winjs/winjs

Python was never good. I’ve tried using winapi through C interop a few times, didn’t like it at all despite what I did wasn’t even too complex.

Delphi and C++ Builder have first class support for COM and UWP. In fact, both had better COM support before VB migrated from VBX to COM with VB 6.0.

JavaScript has first class support on UWP. Of course WinJS is in maintenance BB mode. The future of JavaScript on UWP are PWA apps, with direct access to UWP APIs, no more need for WinJS, which was a Windows 8 library.

Python has supported COM with help from PyWin32 since ages. Hardly any different from VBScript.

> first class support for COM and UWP

When I search “Delphi DirectX”, I only find some Russian website last updated in 2009 and offering Direct3D 10.1 bindings. The newest one is 12, the oldest supported is 11.2.

When I search “Delphi Media Foundation” it’s better, finds bindings updated 4 years ago.

These COM-based technologies are among reasons why I sometimes still pick C++ even for new projects.

Also, in both cases just bindings are not enough, the frameworks are complex, need code samples, stackoverflow community, sometimes books, etc. There’re tons of resources on using these from C++, many from C#, very few for the rest of the languages.

> JavaScript has first class support on UWP

Win32 GDI also has first class support on Win10, just because it’s supported doesn’t mean it will go anywhere. I have doubts MS will continue with that support, they haven’t achieved much and need to do something else, e.g. include CEF in the OS.

> Hardly any different from VBScript.

The difference is that VBScript _is_ COM. All VBScript variables are VARIANT, all strings are VARIANT of VT_BSTR type, and all objects are IDispatch. The interop is not required, COM is already native to the runtime. I can write a COM server in a page long text file with *.wsc extension and VBScript inside, register it with regsvr32.exe, and consume from any language, e.g. `#import "progid:..."` in VC++. I’m not sure you can do same in Python.

So I talk about COM, and you move the goal posts about DirectX in particular, that only implements a subset of COM, which requires writing wrappers by hand, including in .NET, hence Managed DirectX, XNA and SharpDX projects.

Apparently you missed the news regarding PWAs in Windows and its support for native UWP. Again, WinJS got dropped, because it was tied to the Windows 8 programming model, which got improved on Windows 8.1, only to be replaced by UWP on Windows 10.

Win32 GDI actually has "we wish you were all using Win2D and DirectDraw" support on Windows 10.

Here are some examples of automating Excel with Python, http://pbpython.com/windows-com.html, hardly any different from using VBA.

> you move the goal posts about DirectX in particular

In my first comment I wrote that COM became an essential part of WinAPI. Excel runs on Windows but it’s not Windows. DirectX on the other hand is in OS kernel, mayor parts are dxgkrnl.sys. Same applies to media foundation, Windows shell and clipboard, WMI, and many other OS components.

> which requires writing wrappers by hand, including in .NET, hence Managed DirectX, XNA and SharpDX projects.

Right, and all except SharpDX are first-party i.e. made by MS. MS made even more wrappers, WPF, Direct2D and UWP are also manually written wrappers around D3D 9 or 11.

How many wrappers MS made for Delphi or C++ builder?

> you missed the news regarding PWAs in Windows and its support for native UWP

I’m a bit skeptical about the technology.

> examples of automating Excel with Python

Simple IDispatch not that hard even in pure C. It’s more advanced things that require better support for COM: servers, events-callbacks, data structures like arrays and dictionaries, etc.

Rust works great on Windows. I use it every day. Is there anything specifically you had in mind that needs to be improved? Off the top of my head there is some tooling work that needs to be done, but cargo and rustup handle compiling, versioning, and dependency management flawlessly imo.

Person you're replying to probably means the win32 API, i.e. writing GUI applications for windows in Rust.

Rust is still miles away from providing any useful COM/UWP tooling.

I'm sure Rust works great :) But vcpkg was made by Microsoft and I suspect is rather easy to get working on that platform. On the other hand, I've used conan and had no problem e.g. getting FFmpeg working. And, thanks to conan's awesomeness, I can even make it work with clang on windows -- so that e.g. I can use all the latest c++17 features on a library like Boost.Hana and range-v3 (of Eric Niebler fame).

I have high hopes for C++ modules. Seems like that could be a good catalyst for a standard C++ package manager.