> having the widest possible API and ABI, making long term maintenance harder.
For cases where it matters, C++ can do that just fine.
Look at Direct3D, DirectWrite, Media Foundation. They're written in OO C++, and they use IUnknown ABI from COM. They're not COM objects, the ABI is the only feature they took from there.
Apparently, C++ library developers don't care enough.
> you basically give up on a stable narrow interface when shipping header only.
I agree.
But in some cases, you also gain performance not achievable with stable interfaces.
It’s about tradeoffs.
I think modern C++ needs stable ABI and well-isolated modules less than it did 10-20 years ago. 20 years ago people wrote everything in C++. Now C++ lost the majority of the market to higher level and safer languages, it’s only used for components where performance really matters. For such components, runtime overhead of stable ABIs sometimes matters.
For cases where it matters, C++ can do that just fine.
Look at Direct3D, DirectWrite, Media Foundation. They're written in OO C++, and they use IUnknown ABI from COM. They're not COM objects, the ABI is the only feature they took from there.
Apparently, C++ library developers don't care enough.