IssueTracker

A LayoutModifierNode that delegates to a LayoutModifierNode cannot easily delegate the measurement / placement logic, which makes it difficult to build complex nodes. This makes it easy to accidentally break things if you add LayoutModifierNode to a delegating node that already delegated to a LayoutModifierNode.

Similarly, it is also unsupported to delegate to multiple LayoutModifierNodes if the delegating node is not also a LayoutModifierNode. https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:compose/ui/ui/src/commonMain/kotlin/androidx/compose/ui/node/DelegatingNode.kt;l=187

We discussed that we might be able to provide some API like:

fun LayoutModifierNode.then(DelegatableNode): LayoutModifierNode

To allow for limited control over multiple LayoutModifierNodes, where you just control the layout order as if they were separate nodes in the chain.

Example usage:

class A : LayoutModifierNode, Modifier.Node {
  val b = delegate(B())
  val c = delegate(C())
  val layout = b.then(c)
  override fun MeasureScope.measure(...) = layout.measure(...)
}