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by hajimemash 2095 days ago
How have you written backend code in Swift, were you able to use it in places you would normally use e.g. C++?

I'm asking because I like Obj-C/Swift, and am wondering if it's possible through some clang/LLVM magic to be able to code Obj-C/Swift in environments that expect C or C++, for example like in Qt. Like, could I have a traditionally C++ app (Qt app) but have most of my code be in another LLVM-compatible language.
2 comments
ratww 2095 days ago
> Like, could I have a traditionally C++ app (Qt app) but have most of my code be in another LLVM-compatible language

It is possible! I mix Swift and Rust in my day job. I use the C ABI to interface between the two. The Swift layer is very thin and pretty much just a bridge between Rust and Cocoa/UIKit/Metal, but there's nothing stopping you from doing the opposite.

If you're going to bridge Swift with Qt, the sanest way is to use Objective-C++ to wrap Qt calls and call it from Swift.

However keep in mind that the Swift experience in other Operating Systems might not be as good as in Macs. That's why I went with Rust for this project. But things might have changed in the meantime!

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hajimemash 2095 days ago
That sounds really cool.

I did some searching to see people's experiences substituting other languages for C++ through LLVM, and didn't find much other than samples of translated calls.

Given that there would be a big benefit to this (not having to learn a new language, less manual memory management), are there good reasons this isn't way more common?

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ratww 2095 days ago
I thought it was pretty common?

If you use the C ABI you can just link a bunch of object files together.

Rust people are doing it a lot for graphics/game stuff, and there's lots of production MacOS apps mixing ObjC/Swift (because they're transitioning), or consuming C/C++. Of course in this case it's mostly Xcode doing the magic, but behind the scenes it's just calling clang.

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julius_set 2095 days ago
There’s a very vibrant backend community for Swift, Vapor is growing and used in production for a lot of companies.

https://vapor.codes

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