Swift classes can inherit from traits #2363
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Builds on mozilla#2196, mozilla#2204 and mozilla#2297. Closes mozilla#2169.
mhammond
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| if has_callback_interface { | ||
| Ok(class_name) | ||
| } else { | ||
| Ok(format!("{class_name}Protocol")) |
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Is there a good reason why this has "Protocol" appended? IIUC, this is a Rust trait without callback interface support, so Swift can't implement it. In that case, it seems like protocol should get {class_name} which feels like a nicer name, and the class that implements the protocol should get something like{class_name}Impl. I think that's how the other languages handle it.
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This is exactly the same as kotlin which has "Interface" appended
Note that this change doesn't change the hierarchy of any existing objects, it just controls which of the 2 generated classes is used in the inheritance chain.
I'm inclined to agree that the existing hierarchy is odd in these cases, I fear that trying to change that here will accidentally introduce new regressions.
Is this also your understanding - ie, that this patch doesn't change the class hierarchy for existing types, and that doing so is something we'd need to be very careful about?
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Is this also your understanding - ie, that this patch doesn't change the class hierarchy for existing types
Yes agreed.
..and that doing so is something we'd need to be very careful about?
Maybe I have a slight difference of opinion here. I think it could be okay to make the change, since most end-users aren't going to see a difference. If they store a Foo and only use it to call methods from the protocol, it shouldn't matter if Foo is a concrete type that implements the protocol or the protocol itself.
I agree we should be careful, but maybe I'd remove the "very" part.
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Also, I think I got confused and believed that we had already made the change for other languages. If Kotlin works this way, then I think Swift should too. If we decide to change them, let's change both at the same time.
I remember looking into this when doing this for kotlin - the names smelt wrong, but I couldn't work out how to make them good. When UniFFI generates a plain-old trait, it only emits a protocol - there's no concrete implementation. So our But when we need a local impl of the trait (callback/foreign) we'd generate I don't see how to change those names? |
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awesome thanks @mhammond ! |
Builds on #2196, #2204 and #2297. Closes #2169.