ConstA transition into the screen id: calling it runs the target's enter and
returns the target's handle, whose origin is the handle the edge was
taken from (none for a tab). step maps the screen's state (and the
caller's arguments) to the edge's source, ordinal skip and the target's
input. An edge that takes arguments declares their schema (a tuple) third,
so a trail can store them.
The edge is taken only while its screen is on top (an item's: while its
host is), else it dies with ScreenNotOnTopError (a defect); an input the target's schema refuses
is ScreenEdgeInputError.
The target's handle is typed by the registry, not by the handle the edge
is taken from: its origin is what can open the target
(ScreenOpenersOf, ScreenItemOpenersOf), so an action that
takes its own screen's edge (handleAction) uses this same declaration.
A transition into the screen id: calling it runs the target's enter and
returns the target's handle, whose origin is the handle the edge was
taken from (none for a tab). step maps the screen's state (and the
caller's arguments) to the edge's source, ordinal skip and the target's
input. An edge that takes arguments declares their schema (a tuple) third,
so a trail can store them.
The edge is taken only while its screen is on top (an item's: while its
host is), else it dies with ScreenNotOnTopError (a defect); an input the target's schema refuses
is ScreenEdgeInputError.
The target's handle is typed by the registry, not by the handle the edge
is taken from: its origin is what can open the target
(ScreenOpenersOf, ScreenItemOpenersOf), so an action that
takes its own screen's edge (handleAction) uses this same declaration.
The transitions of the platform's screens, typed by AndroidScreens.