add from! macro

crates/tek/src/core.rs

@@ -10,3 +10,13 @@ pub use self::{
     input::Handle,
     output::Render
 };
+
+/// Prototypal case of implementor macro.
+/// Saves 4loc per data pats.
+#[macro_export] macro_rules! from {
+    (|$self:ident: $Source:ty| $Target:ty = $cb:expr) => {
+        impl From<$Source> for $Target {
+            fn from (state: $Source) -> Self { $cb }
+        }
+    };
+}

crates/tek/src/tui/arranger_mode_v.rs

@@ -5,17 +5,11 @@ pub struct ArrangerVColSep {
     scenes_w: u16,
     sep_fg: Color,
 }
-
-impl From<&ArrangerTui> for ArrangerVColSep {
-    fn from (state: &ArrangerTui) -> Self {
-        Self {
+from!(|source:&ArrangerTui|ArrangerVColSep = Self {
     cols:     track_widths(state.tracks()),
     scenes_w: 3 + ArrangerScene::longest_name(state.scenes()) as u16,
     sep_fg:   TuiTheme::separator_fg(false),
-        }
-    }
-}
-
+});
 render!(<Tui>|self: ArrangerVColSep|render(move|to: &mut TuiOutput|{
     let style = Some(Style::default().fg(self.sep_fg));
     Ok(for x in self.cols.iter().map(|col|col.1) {
@@ -145,8 +139,18 @@ pub struct ArrangerVHead<'a> {
     timebase: &'a Arc<Timebase>,
     current:  &'a Arc<Moment>,
 }
+from!(<'a>|state: &'a ArrangerTui|ArrangerVHead<'a>, { // A
+    tracks:   &state.tracks,
+    cols:     track_widths(state.tracks()),
+    focused:  true,
+    selected: state.selected,
+    scenes_w: 3 + ArrangerScene::longest_name(state.scenes()) as u16,
+    header_h: 3,
+    timebase: state.clock().timebase(),
+    current:  &state.clock().playhead,
+});
 
-impl<'a> From<&'a ArrangerTui> for ArrangerVHead<'a> {
+impl<'a> From<&'a ArrangerTui> for ArrangerVHead<'a> { // B
     fn from (state: &'a ArrangerTui) -> Self {
         Self {
             tracks:   &state.tracks,