Value isn't encodable/decodable

[euclio]

I'm (slowly) working on #40, and I'm running into a problem with representing heterogenous lists (for arguments). I've resorting to using Vec<Value> as a struct field. However, since Value isn't encodable, it's difficult to serialize it as part of a larger struct.

[3Hren]

It's a bit tricky to implement. I'll try to implement for serde.

[Mange]

Would this make it possible to handle something similar to this example from serde_json?

//#![feature(custom_derive, plugin)]
//#![plugin(serde_macros)]

extern crate serde_json;

use serde_json::Value;

fn main() {
    let data: Value = serde_json::from_str("{\"foo\": 13, \"bar\": \"baz\"}").unwrap();
    println!("data: {:?}", data);
    // data: {"bar":"baz","foo":13}
    println!("object? {}", data.is_object());
    // object? true

    let obj = data.as_object().unwrap();
    let foo = obj.get("foo").unwrap();

    println!("array? {:?}", foo.as_array());
    // array? None
    println!("u64? {:?}", foo.as_u64());
    // u64? Some(13u64)

    for (key, value) in obj.iter() {
        println!("{}: {}", key, match *value {
            Value::U64(v) => format!("{} (u64)", v),
            Value::String(ref v) => format!("{} (string)", v),
            _ => format!("other")
        });
    }
    // bar: baz (string)
    // foo: 13 (u64)
}

E.g. deserializing some generic MessagePack data, or have I misunderstood this issue?
There does not seem to exist any messagepack library for rust that handles this case yet, AFAIK.

[3Hren]

You can deserialize the bytearray into a msgpack::Value and then work with it as usual ADT.

This issue is about implementing serde::Serialize/Deserialize for rmp::Value.

[SuperFluffy]

It would be fantastic if we could get this. serde_json does something similar, giving in particular a structure like Object(BTreeMap<String, Value>), which makes it very convenient to construct non-heterogeneous structures (by which I mean something like {"foo": T, "bar": U}.

[3Hren]

Please check this as there is the first look on serialization support for Value. If everything is ok, I'm going to implement deserization too.

Unfortunately, it's required to wrap Value to be able to impl external trait.

[euclio]

@3Hren Have you experimented with implementing Deserialize for Value?

[3Hren]

@euclio have no time for this issue, sorry :( Still, the code should be almost the same as in #73.

[3Hren]

Now after I've moved Value from rmp into rmpv crate it is possible to natively serialize/deserialize values using serde (cargo test features=with-serde).

https://github.com/3Hren/msgpack-rust/blob/master/rmpv/src/ext.rs