[kccqzy]

That's a C99 feature, designated initializer. Hardly modern. Yes it was ported to C++ relatively late, but it happened in C++20.

[rwmj]

Don't C++ designated initializers require you to initialize in struct order? That makes them kind of annoying to use.

[manwe150]

Wouldn’t c99 also make you name the type there (looking sort of like a cast), further straying from being just kwargs? I thought this was a c++ deduction feature for it to bind the initializer to whether method could take that list