From 74266edf29c99780b33b5501fd1aae9d4251231c Mon Sep 17 00:00:00 2001
From: Gergely Nagy <ngg@users.noreply.github.com>
Date: Fri, 5 Jul 2019 09:16:26 +0200
Subject: [PATCH] replace CbFunc with Box<FnOnce()> (#351)

Since Rust 1.35, Box<FnOnce()> compiles, we can remove the workaround.
---
 examples/vpv.rs |  2 +-
 src/cursive.rs  | 28 +++++-----------------------
 src/lib.rs      |  2 +-
 3 files changed, 7 insertions(+), 25 deletions(-)

diff --git a/examples/vpv.rs b/examples/vpv.rs
index 7f63bbb..ce5f8d9 100644
--- a/examples/vpv.rs
+++ b/examples/vpv.rs
@@ -137,7 +137,7 @@ cargo run --example vpv </dev/zero >/dev/null",
             }
 
             // When we're done, shut down the application
-            cb_sink.send(Box::new(|s: &mut Cursive| s.quit())).unwrap();
+            cb_sink.send(Box::new(Cursive::quit)).unwrap();
         });
         siv.set_autorefresh(true);
     }
diff --git a/src/cursive.rs b/src/cursive.rs
index 495da61..970bd41 100644
--- a/src/cursive.rs
+++ b/src/cursive.rs
@@ -43,8 +43,8 @@ pub struct Cursive {
 
     backend: Box<dyn backend::Backend>,
 
-    cb_source: Receiver<Box<dyn CbFunc>>,
-    cb_sink: Sender<Box<dyn CbFunc>>,
+    cb_source: Receiver<Box<dyn FnOnce(&mut Cursive) + Send>>,
+    cb_sink: Sender<Box<dyn FnOnce(&mut Cursive) + Send>>,
 
     // User-provided data.
     user_data: Box<dyn Any>,
@@ -57,25 +57,7 @@ pub struct Cursive {
 pub type ScreenId = usize;
 
 /// Convenient alias to the result of `Cursive::cb_sink`.
-pub type CbSink = Sender<Box<dyn CbFunc>>;
-
-/// Asynchronous callback function trait.
-///
-/// Every `FnOnce(&mut Cursive) -> () + Send` automatically
-/// implements this.
-///
-/// This is a workaround only because `Box<FnOnce()>` is not
-/// working and `FnBox` is unstable.
-pub trait CbFunc: Send {
-    /// Calls the function.
-    fn call_box(self: Box<Self>, _: &mut Cursive);
-}
-
-impl<F: FnOnce(&mut Cursive) -> () + Send> CbFunc for F {
-    fn call_box(self: Box<Self>, siv: &mut Cursive) {
-        (*self)(siv)
-    }
-}
+pub type CbSink = Sender<Box<dyn FnOnce(&mut Cursive) + Send>>;
 
 cfg_if::cfg_if! {
     if #[cfg(feature = "blt-backend")] {
@@ -330,7 +312,7 @@ impl Cursive {
     /// let mut siv = Cursive::dummy();
     ///
     /// // quit() will be called during the next event cycle
-    /// siv.cb_sink().send(Box::new(|s: &mut Cursive| s.quit())).unwrap();
+    /// siv.cb_sink().send(Box::new(|s| s.quit())).unwrap();
     /// # }
     /// ```
     pub fn cb_sink(&self) -> &CbSink {
@@ -877,7 +859,7 @@ impl Cursive {
         // Then, handle any available callback
         while let Ok(cb) = self.cb_source.try_recv() {
             boring = false;
-            cb.call_box(self);
+            cb(self);
 
             if !self.running {
                 return true;
diff --git a/src/lib.rs b/src/lib.rs
index e75f110..4326cad 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -101,7 +101,7 @@ mod utf8;
 
 pub mod backend;
 
-pub use self::cursive::{CbFunc, CbSink, Cursive, ScreenId};
+pub use self::cursive::{CbSink, Cursive, ScreenId};
 pub use self::printer::Printer;
 pub use self::rect::Rect;
 pub use self::vec::Vec2;