widget fn ret macro

src/base/trait_fns.rs

@@ -1,5 +1,5 @@
 use super::*;
-use crate::{UIRegion, Ui, Vec2, WidgetArrLike, WidgetFn, WidgetLike};
+use crate::{UIRegion, Ui, Vec2, WidgetArrLike, WidgetFn, WidgetFnRet, WidgetLike};
 
 pub trait BaseWidget {
     fn pad(self, padding: impl Into<Padding>) -> impl WidgetLike<Widget = Regioned>;
@@ -23,19 +23,11 @@ impl<W: WidgetLike> BaseWidget for W {
 }
 
 pub trait BaseWidgetArr<const LEN: usize> {
-    fn span(
-        self,
-        dir: Dir,
-        lengths: [impl Into<SpanLen>; LEN],
-    ) -> WidgetFn<impl FnOnce(&mut Ui) -> Span, Span>;
+    fn span(self, dir: Dir, lengths: [impl Into<SpanLen>; LEN]) -> WidgetFnRet!(Span);
 }
 
 impl<const LEN: usize, Wa: WidgetArrLike<LEN>> BaseWidgetArr<LEN> for Wa {
-    fn span(
-        self,
-        dir: Dir,
-        lengths: [impl Into<SpanLen>; LEN],
-    ) -> WidgetFn<impl FnOnce(&mut Ui) -> Span, Span> {
+    fn span(self, dir: Dir, lengths: [impl Into<SpanLen>; LEN]) -> WidgetFnRet!(Span) {
         let lengths = lengths.map(Into::into);
         WidgetFn(move |ui| Span {
             dir,

src/layout/widget.rs

@@ -59,9 +59,17 @@ pub trait WidgetLike {
 /// A function that returns a widget given a UI.
 /// Useful for defining trait functions on widgets that create a parent widget so that the children
 /// don't need to be IDs yet
+pub trait WFn<W> = FnOnce(&mut Ui) -> W;
 pub struct WidgetFn<F: FnOnce(&mut Ui) -> W, W>(pub F);
 pub struct WidgetIdFn<F: FnOnce(&mut Ui) -> WidgetId<W>, W>(pub F);
 
+macro_rules! WidgetFnRet {
+    ($W:ident) => {
+        WidgetFn<impl FnOnce(&mut Ui) -> $W, $W>
+    };
+}
+pub(crate) use WidgetFnRet;
+
 pub trait _WidgetFn<W: Widget> {
     fn call(ui: &mut Ui) -> W;
 }