Question about compose.foundation: why is `DefaultFlingBehavior` private? To extend it I need to cop...

# compose

[vide]

Question about compose.foundation: why is DefaultFlingBehavior private? To extend it I need to copy/paste code to my own codebase which is suboptimal 😕

[chanjungskim]

How do you customize it?

[vide]

I'm adding some normalization to the fling speed. It would be easy to call super.performFling() with a modified initial velocity

[Albert Chang]

You don't need to. You can easily do something like this:

@Composable
fun rememberMyFlingBehavior(): FlingBehavior {
    val defaultFlingBehavior = ScrollableDefaults.flingBehavior()
    return remember(defaultFlingBehavior) {
        object : FlingBehavior {
            override suspend fun ScrollScope.performFling(initialVelocity: Float): Float =
                with(defaultFlingBehavior) { performFling(adjustedVelocity) }
        }
    }
}

[Albert Chang]

"Composition over inheritance" is a principle used everywhere in compose.

[vide]

now I feel really dumb 😅

[vide]

thanks for reminding me of this style!

[chanjungskim]

I found a similar answer in stackoverflow: https://stackoverflow.com/questions/72444556/swipe-sensitivity-for-horizontalpager-in-compose

[chanjungskim]

"Composition over inheritance" seems difficult to come up in my head.

[vide]

I was implementing this but actually not so sure about the simplicity anymore. It seems like I don't really understand the kotlin syntax here... why is the with function necessary?

[Albert Chang]

Because performFling() function has a receiver type and that's how you call a member function with receiver.

[vide]

this is relevant reading for anyone else wondering about this: I didn't really know you could even do this! https://kotlinlang.org/docs/extensions.html#declaring-extensions-as-members

[vide]

Is there even any other way to do this without using with? Calling a member function with receiver?

[Albert Chang]

You can also use defaultFlingBehavior.run { performFling(velocity) }.

[chanjungskim]

Is this https://en.wikipedia.org/wiki/Composition_over_inheritance the same concept?