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

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

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.

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

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

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

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

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

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

Again, `Modifier.Node` implementations shouldn’t be public

&gt; 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.
&gt; 
You can generate `hashCode` and `equals` methods <https://www.jetbrains.com/help/idea/generating-code.html#generate-equals-hashcode|https://www.jetbrains.com/help/idea/generating-code.html#generate-equals-hashcode>

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

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

<@U0KMMQA20> 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?

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. 