comments

Signed-off-by: Yoshua Wuyts <yoshuawuyts@gmail.com>

src/io/write/mod.rs

@@ -234,6 +234,9 @@ extension_trait! {
         where
             Self: Unpin,
         {
+            // In order to not have to implement an async version of `fmt` including private types
+            // and all, we convert `Arguments` to a `Result<Vec<u8>>` and pass that to the Future.
+            // Doing an owned conversion saves us from juggling references.
             let mut string = String::new();
             let res = std::fmt::write(&mut string, fmt)
                 .map(|_| string.into_bytes())

src/io/write/write_fmt.rs

@@ -17,7 +17,6 @@ impl<T: Write + Unpin + ?Sized> Future for WriteFmtFuture<'_, T> {
     type Output = io::Result<()>;
 
     fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
-
         // Process the interal Result the first time we run.
         if self.buffer.is_none() {
             match self.res.take().unwrap() {
@@ -26,15 +25,16 @@ impl<T: Write + Unpin + ?Sized> Future for WriteFmtFuture<'_, T> {
             };
         }
 
+        // Get the types from the future.
         let Self { writer, amt, buffer, .. } = &mut *self;
         let mut buffer = buffer.as_mut().unwrap();
 
+        // Copy the data from the buffer into the writer until it's done.
         loop {
             if buffer.is_empty() {
                 futures_core::ready!(Pin::new(&mut **writer).poll_flush(cx))?;
                 return Poll::Ready(Ok(()));
             }
-
             let i = futures_core::ready!(Pin::new(&mut **writer).poll_write(cx, &mut buffer))?;
             if i == 0 {
                 return Poll::Ready(Err(io::ErrorKind::WriteZero.into()));