Way to pair serialize_with and deserialize_with into one attribute

[dtolnay]

#[serde(serialize_with = "url_serde::serialize",
        deserialize_with = "url_serde::deserialize")]

This gets tedious because you almost always want these paired. Can we deduplicate into one attribute?

#[serde(with = "url_serde")]

[oli-obk]

So the use = "type" would require type to implement both Serialize and Deserialize (barring further attributes like deserialize_default)?

[dtolnay]

I haven't thought about how it would work yet.

I think the way you are suggesting is you give the attribute a path to a wrapper type:

struct Url(url::Url);
impl Serialize for Url { ... }
impl Deserialize for Url { ... }

A different approach that would be more similar to serialize_with and deserialize_with would be to give the attribute a path to a module containing ser and de functions:

mod url {
    fn serialize<S>(...) { ... }
    fn deserialize<D>(...) { ... }
}

Right now I am leaning toward the module approach because it means that simple wrapper libraries like url_serde can be used just with #[serde(use = "url_serde")].

[oli-obk]

Oh, your idea is much more general, since it also supports the case where the "wrapper type" is not a wrapper type at all, but e.g. some random type from another crate.

[dtolnay]

@nox my mod proposal would work with hyper_serde out of the box without any code change on your end.

 #[derive(Serialize, Deserialize)]
 struct MyStruct {
-    #[serde(deserialize_with = "hyper_serde::deserialize",
-            serialize_with = "hyper_serde::serialize")]
+    #[serde(with = "hyper_serde")]
     headers: Headers,
 }

Any concerns or suggestions?

[dtolnay]

I released this in 0.9.8.