如何实现许多类似的特质方法？

Question

I am implementing the Serde Serializer trait which has a lot of methods. Many of them look quite similar (for example those for integer types just copy bytes to some buffer), so it would be nice to generate them somehow. Can I write some generic function or macro to implement many of them with one method (macro)?

I have something like this:

use serde::Serializer;
use byteorder::{WriteBytesExt, LittleEndian};

struct MySerializer {
     ...
}

impl Serializer for MySerializer {
    fn serialize_i32(&mut self, v:i32) -> Result<(), Error> {
        try!(self.buffer.write_i32::<LittleEndian>(v));
    }
    fn serialize_u8(&mut self, v:u8) -> Result<(), Error> {
        try!(self.buffer.write_u8::<LittleEndian>(v));
    }
    // many similar looking functions here
}

Answer 1

I found and example in serde/bench project:

macro_rules! impl_nums {
    ($ty:ty, $dser_method:ident, $visitor_method:ident, $reader_method:ident) => {
        #[inline]
        fn $dser_method<V>(&mut self, mut visitor: V) -> Result<V::Value>
            where V: Visitor
        {
            let value = try!(self.reader.$reader_method::<NativeEndian>());
            visitor.$visitor_method(value)
        }
    };
}

impl_nums!(u16, deserialize_u16, visit_u16, read_u16);
impl_nums!(u32, deserialize_u32, visit_u32, read_u32);
....

It looks like for now it is the best possible way to do it - concat_idents! macro is unstable, and is not very useful acording to this github issue .