QtCS2024 Breaking The Monolith

Notes

• Should we split qtbase even further than it is? Core separate from Gui
• Should add-on modules support require only the last Qt LTS?
• Whatever we do, we shouldn't lose our consistency in quality
  • Compiler, platform requirements, C++ level, etc.
• Danger: incompatible versions, if "max versions" exist
• Danger: fragmentation of contributors' attentions
  • Right now, we are "all in" for every release and we are all invested in all modules' quality

Bring back Qt Solutions - source-only releases

• Source-compatibility only and mostly
• Should be easy to integrate into existing projects (used to be just a .pri file, for qmake)
• Issue is discoverability - Qt Market Place?

Installation and packaging

• Maintanance tool should support installing things
  • But shouldn't make things more confusing!
  • Different version numbers going out-of-sync would be confusing
• C++ doesn't have a good way outside of this, which makes things difficult for users
  • This needs to be investigated first

Look at what the KDE Frameworks split and how the process went, pros and cons

• Splitting too-fine-grained has a drawbacks, for users who need more than just a few
• Dependencies become non-obvious
• Left-over modules that become dumping ground because they weren't cleaned up
• All modules still released in-sync

Use of private API is extensive in Qt between libraries

• Too convenient, also difficult to change now without BC break
• Intra-module dependencies may be OK, inter-module ones with different release cycles are not
• Create an intermediate class between public and private API ("protected" API)
  • Not as well documented
  • Documented as meta-stable: stable for only a period of time, but may change beyond that

Is it fine right now?

• Runtime dependencies are mostly ok already (no deploying of QtWidgets in Android apps for example)
• Splitting further out or having different release cycles may be counter-productive
• Does allow us to immediately use new APIs in all modules
  • No waiting for the new content to have been present in the last LTS
  • But isn't this what stable user applications already face?
• But may be required for some modules, for other reasons
  • qtwebengine is an example

Use the feature system more

• Allow depopulating some libraries for constrained systems