Why do `ModifierNodeElement` implementations usually provide their own hashCode and equals implement...

# compose

[vide]

Why do ModifierNodeElement implementations usually provide their own hashCode and equals implementations? What about using a data class?

[Francesc]

they don't need the extra baggage that comes from a data class, so why have it. Also, in libraries, you should avoid data classes altogether

[vide]

So do the extra generated copy() and componentN() result in a realistically larger generated code size? I would imagine hand-writing hashcodes is also more error prone.

[vide]

I haven't heard about avoiding data classes for libraries, is there some reasoning for that?

[vide]

I'm just curious blob smile

[Francesc]

there's an article from JW, let me find it

[Francesc]

https://jakewharton.com/public-api-challenges-in-kotlin/

[Francesc]

for the other question, when you develop a library, every extra method counts

[Zach Klippenstein (he/him) [MOD]]

Internally we do use data classes for modifier nodes occasionally. They should be private classes though so it’s a very easy decision to change later on

[vide]

well that's a loadful of good arguments from Jake, thanks for the link gratitude thank you

[Zach Klippenstein (he/him) [MOD]]

Again, Modifier.Node implementations shouldn’t be public

[Valentin Gusselnikov]

So do the extra generated copy() and componentN() result in a realistically larger generated code size? I would imagine hand-writing hashcodes is also more error prone.

You can generate hashCode and equals methods https://www.jetbrains.com/help/idea/generating-code.html#generate-equals-hashcode

[shikasd]

I'd say don't worry about writing it by hand if you don't have to support ABI compatibility

[vide]

Thanks for the replies. I was wondering about this in context of this change: https://android-review.googlesource.com/c/platform/frameworks/support/+/2821836.

@Zach Klippenstein (he/him) [MOD] I'm still wondering about the approach of not publishing Modifier.Node implementations, wouldn't it be useful to have as much as possible public so that external implementations can delegate to them?

[Zach Klippenstein (he/him) [MOD]]

If you want to support delegation, then yea, but I would only do that if you really need to. Delegation is hard to do right anyway.