They are likely referring to the scope of fine-grained specialization and compile-time codegen that is possible in modern C++ via template metaprogramming. Some types of complex optimizations common in C++ are not really expressible in Rust because the generics and compile-time facilities are significantly more limited.
As with C, there is nothing preventing anyone from writing all of that generated code by hand. It is just far more work and much less maintainable than e.g. using C++20. In practice, few people have the time or patience to generate this code manually so it doesn't get written.
Effective optimization at scale is difficult without strong metaprogramming capabilities. This is an area of real strength for C++ compared to other systems languages.
Again, can you provide an example or two? Its hard to agree or disagree without an example.
I think all C++ wild template stuff can be done via proc macros. Eg, in rust you can add #[derive(Serialize, Deserialize)] to have a highly performant JSON parser & serializer. And thats just lovely. But I might be wrong? And maybe its ugly? Its hard to tell without real examples.
Specialization isn’t stable in Rust, but is possible with C++ templates. It’s used in the standard library for performance reasons. But it’s not clear if it’ll ever land for users.
> As with C, there is nothing preventing anyone from writing all of that generated code by hand. It is just far more work and much less maintainable than e.g. using C++20.
It's also still less elegant, but compile time codegen for specialisation is part of the language (build system?) with build.rs & macros. serde makes strong use of this to generate its serialisation/deserialisation code.
As with C, there is nothing preventing anyone from writing all of that generated code by hand. It is just far more work and much less maintainable than e.g. using C++20. In practice, few people have the time or patience to generate this code manually so it doesn't get written.
Effective optimization at scale is difficult without strong metaprogramming capabilities. This is an area of real strength for C++ compared to other systems languages.