writeable

writeable is a utility crate of the [ICU4X] project.

It includes [Writeable], a core trait representing an object that can be written to a sink implementing std::fmt::Write. It is an alternative to std::fmt::Display with the addition of a function indicating the number of bytes to be written.

Writeable improves upon std::fmt::Display in two ways:

1. More efficient, since the sink can pre-allocate bytes.
2. Smaller code, since the format machinery can be short-circuited.

Examples

```rust use std::fmt; use writeable::assertwriteableeq; use writeable::LengthHint; use writeable::Writeable;

struct WelcomeMessage<'s> { pub name: &'s str, }

impl<'s> Writeable for WelcomeMessage<'s> { fn writeto(&self, sink: &mut W) -> fmt::Result { sink.writestr("Hello, ")?; sink.writestr(self.name)?; sink.writechar('!')?; Ok(()) }

fn writeable_length_hint(&self) -> LengthHint {
    // "Hello, " + '!' + length of name
    LengthHint::exact(8 + self.name.len())
}

}

let message = WelcomeMessage { name: "Alice" }; assertwriteableeq!(&message, "Hello, Alice!");

// Types implementing Writeable are recommended to also implement fmt::Display. // This can be simply done by redirecting to the Writeable implementation: writeable::impldisplaywithwriteable!(WelcomeMessage<'>); ```

More Information

For more information on development, authorship, contributing etc. please visit ICU4X home page.