View source for QtCS25 - Using Qt Quick with other programming languages

==Session Summary==

''Presentation by Vladimir and Discussion'' 
==Session Owners==

''Vladmir Minenko''

''Fabian Kosmale''

==Notes==
Roadmap see Vladimir's slides.

* .Net, Java, Rust, Swift, Python covered
* What to do about JavaScript? Needs more research
* People ask about Go
* Maybe network-based transport between Qt Quick and other language? REST, OpenAPI?

How does it actually work?? Can we have an example?

Python as example:

* Bridge exports a single funtion
* Function accepts a Python container
* Makes it available in QML, via reflection, as a singleton (or QAbstractItemModel? or some property?)
* Idea:
** Provide small library
** Use native types from respective language
** Do language-dependent magic to transform data for QML
*** Rust: procedural macros
*** Python, Java, Swift: reflection
*** C#: don't know yet (currently generating C++ code)
** expose limited subset of data to QML

How does this interact with tooling/qmlcachegen etc?

* We can't do all the type registration at run time (but how else? and what is build time even?)
* Compilation to C++ is probably not a good idea
* Optimized byte code compilation might work

What about other QML modules? Can they be used? For example QtMultimedia

* Can use everything exposed to QML
* Custom rendering probably not

What is the use case?

* Qt-owned UI with different host language
* For Python piggy-back on Qt for Python
* For Rust piggy-back to CXX-Qt
* No combining with other frameworks for now
** Embedding is a different project, for example see android

What types will be available?

* Some primitive types: string, url, numbers, etc
* No custom QQuickItem for now (that would be full bindings)
* Maybe simple QObject-derived types
* We hope that only exposing data (value types) is enough

What IDE will be used? Qt Creator or the language-specific one?

* We don't know yet
* We want to support language-native IDEs
* We need to generalize our QML tooling (not only qmlls, but also profiler or debugger)

Does data need to be copied when moving between other language and QML?

* Depends on host language
* Python has dictionaries; hopefully we can use them to back JavaScript objects in QML

Would you be able to mix e.g. Qt for Python with the python bridget?

* With python and rust, probably
* Not with swift because we don't have full bindings
* With probably yes, using QtJambi
Need to expand QML API of QtQuick to prevent the urge to use C++ API

Can you use multiple different bridges in one app?

* Nobody brought this up yet. We don't know yet.
* What about moving data from one backend language to another via QML?

What about performance?

=== Presentation Slides ===
[[File:QtCS 2025 - Qt Bridges.pdf|thumb]]
[[Category:QtCS2025]]