Splitting implementation and interface in C++ [LWN.net]

Splitting implementation and interface in C++

Posted Feb 25, 2025 11:16 UTC (Tue) by taladar (subscriber, #68407)
In reply to: Splitting implementation and interface in C++ by farnz
Parent article: Rewriting essential Linux packages in Rust

Whenever a project is a large single library or repository the answer is usually "because the tooling makes it painful to split it up", not "there is a good reason to have a humongous pile of code".

Splitting implementation and interface in C++

Posted Feb 25, 2025 21:51 UTC (Tue) by ras (subscriber, #33059) [Link]

> the answer is usually "because the tooling makes it painful to split it up",

Or "it's faster because we can optimise".

My favourite counter example to this is LVM / DM vs ZFS, possibly because I'm a recent user of ZFS. LVM / DM / traditional file system give you similar a outcome to ZFS, albeit with a more clunky interface because "some assembly is required". The zfs CLI is nice. However by every other metric I can think of LVM / DM / ... stack wins. The stack is faster, the modular code is much easier to understand, they have less bugs (I'm tempted to far less), and you have more ways of doing the same thing.

This is surprising to me. I would have predicted to the monolithic style to win on speed at least, and are easier to extend (which evidence against "it's easier to develop that way").

I guess there is a size when the code base becomes too much for one person. At that point it should become modular, with each module maintained by different people sporting an interface that requires screaming and yelling to change. But by that time it's already a ball of mud, I guess the tooling is a convenient thing to blame for not doing the work required to split it up.