CppCon
7 HN recommenders · recommended in 13 months, 2017–2022
1:31:14 · 53K views · Sep 28, 2017
Titus Winters' CppCon 2017 talk argues for C++ and Google's Abseil to be maintained as a live at head language, relying on testing and automated tooling rather than never changing or promising no compatibility. It covers Hyrum's law and the limits of semantic versioning.
Recommended whenever versioning, semver, monorepos and backward compatibility are debated, for its nuanced treatment of dependencies.
14 comments from Hacker News
> If you go listen to Google people talk about dependency/version management. It's like they think it's global lock vs inconsistency. Monorepo or chaos. This false choice irks me. I watched this talk: this video I’d say this is a much more nuanced look at dependencies & versioning. We all know these days that something like semantic versioning is not enough, because it is too easy to depend on behavior which the developers of your dependencies did not expect you to depend on. So you need something more powerful than just having a bunch of developers get together and agree not to break each others’ code. Bazel is a part of that solution—if you can analyze and understand the dependencies in a project, and do so in a very automatic and reliable way, you can provide people with tools tools for updating downstream code when upstream code changes. I think people are focusing too much on Bazel as only a build system and not as part of a platform for building developer tooling, and people are focusing too much on Bazel’s original incarnation as a build system for a massive monorepo. I think there’s also a reality that we must deal with that is—as software gets larger and more complex, and as we have more dependencies, relying on version pinning for stability is losing ground as a technique for making our software more reliable. We have many more dependencies in our software now, so just subscribing to a mail feed of all of the version bumps in the libraries you use would be enough to dr
> You are totally correct that to achieve the same performance, correctness, and overall master level "green"ness in a multirepo system you would have to either define or detect dependencies and dependent repos, build the entire affected chain, and test the result. That part is much easier in monorepo. You also would need to do that as an atomic operation (in the mono-repo + especially with a commit queue you're building on the atomicity of git). Having to unwinding that transaction if you aren't atomic can get you into a big mess at larger scales. Here's a good related talk: C++ as a "Live at Head" language: this video by Titus Winters (from Google).
Usually that problem is dealt with combination of: * Automation. * Ability to change other people's code safely, possibly gated by code review approval. Cultural and technical (e.g. unit tests must exist and be maintained) barriers may apply. * Making incremental changes that are backward compatible (at least until you migrated all clients so you can cleanup later) I recommend this talk this video (even if the scope is broader than your question) (ex-googler)
For another perspective on “semver is a lie,” see the “Live at Head” talk from Titus Winters of the Google core C++ team. this video TL;DW: By Hyrum’s law, at sufficient scale, there’s no such thing as a non-breaking change (including changing comments). Embrace that, and test sufficiently that you can always take the latest dependency but detect when it breaks.
There is a great talk by their C++ dev team about how a build everything from source, mono repo really helps with C++ change enablement this video Personally, I’d have to agree that at a minimum a mono repo per distinct product role (server side in one mono repo, desktop software in one mono repo) is immensely valuable.