This was an explicit design intent from early days of C++. I remember discussing Lisp's macro capabilities with Stroustrup back in the early 90s and him saying he had always wanted to have that in C++ and templating was the first step.

Shame it took so long to actually arrive.

Which reveals the problem D has finding any relevant niche, as the community cannot decide into which direction to head into.

Java and C# also have acquired many capabilities that for 10 years were a plus from D over them.