What about allocators in C++ STL (Standard Template Library)? Honestly, I have been reading & writing C++ for a squillion years, and (1) I have never used an allocator myself, and (2) never seen anyone else use it. (Granted, I have not seen a huge number of enterprise C++ code bases.)
they are very awkward to use in the current STL, they are part of the template definition. Back in the day EASTL did allocators much better but it never became a thing.
