[KyleJ61782]

I concur with the description of the Delphi implementation, as I've navigated it numerous times myself. I guess I don't understand the author's negative tone with regard to the C++/Delphi implementation. There's going to be overhead with any choice made and C++ and Delphi made the choice to sacrifice memory usage for speed. Furthermore, the only part that really scales with the number of objects is the extra vtable pointer for each implemented interface in each newly constructed object. Hardly a significant overhead in today's memory-prolific computing environment. Also, pointer fixup thunks and unconditional jumps are easy to speculatively handle.

[latk]

The author is interested in PL design, and thinks that while C++ style object implementations are great at offering compatibility with certain systems or interfaces, other approaches allow for far nicer semantics in a greenfield programming language.

For example, fat pointers make it possible to implement interfaces for existing types. I have experienced that as game-changing in Haskell, Go, Rust.

I also disagree that any memory usage can be handwaved as “no longer relevant today”. Electron, or garbage collection: perhaps. But object size affects cache pressure, and cache utilization is critical to performance. C++ is typically good at keeping objects small, except when it comes to multiple inheritance.

[KyleJ61782]

Honest question: do you have a real-world example that indicates that the extra pointers added due to multiple inheritance actually results in performance degradation due to extra cache pressure?