widget_index!() { /* proc-macro */ }Expand description
Index of a child widget
This macro is usable only within an impl_self, impl_scope! or
impl_anon! macro using the widget attribute.
Example usage: widget_index![self.a]. If a is a child widget (a field
marked with the #[widget] attribute), then this expands to the child
widget’s index (as used by Widget::get_child). Otherwise, this is an error.