I used extensions with multiple receivers for adding context inside data-structures. Example: I have a layout-algorithm for a grid that takes sections: in

I used extensions with multiple receivers for adding context inside data-structures. Example: I have a layout-algorithm for a grid that takes sections: interface Section { val title: String fun something() } Then I have the grid-algorithm. Inside I store expanded/collapsed state for each section. When I use a member-extension with both receivers I can write that pretty conveniently: class GridLayout(sections: List<Section>) { /* the state */ val expandedSections = mutableSetOf<Section>() /* the extensions I need in this context */ val Section.isExpanded get() = this@Section in expandedSections fun Section.expand() = expandedSections += this@Section fun compute() { ... if (!section1.isExpanded) { section2.expand() } ... } }