Serde rustdoc

serde/Cargo.toml

@@ -26,3 +26,6 @@ unstable-testing = ["clippy", "unstable", "std"]
 
 [dependencies]
 clippy = { version = "^0.*", optional = true }
+
+[dev-dependencies]
+serde_derive = "0.9.0-rc3"

serde/src/bytes.rs

@@ -1,4 +1,20 @@
-//! Helper module to enable serializing bytes more efficiently
+//! Wrapper types to enable optimized handling of `&[u8]` and `Vec<u8>`.
+//!
+//! Without specialization, Rust forces us to treat `&[u8]` just like any other
+//! slice and `Vec<u8>` just like any other vector. In reality this particular
+//! slice and vector can often be serialized and deserialized in a more
+//! efficient, compact representation in many formats.
+//!
+//! When working with such a format, you can opt into specialized handling of
+//! `&[u8]` by wrapping it in `bytes::Bytes` and `Vec<u8>` by wrapping it in
+//! `bytes::ByteBuf`.
+//!
+//! Rust support for specialization is being tracked in
+//! [rust-lang/rust#31844][specialization]. Once it lands in the stable compiler
+//! we will be deprecating these wrapper types in favor of optimizing `&[u8]`
+//! and `Vec<u8>` out of the box.
+//!
+//! [specialization]: https://github.com/rust-lang/rust/issues/31844
 
 use core::{ops, fmt, char, iter, slice};
 use core::fmt::Write;
@@ -6,14 +22,36 @@ use core::fmt::Write;
 use ser;
 
 #[cfg(any(feature = "std", feature = "collections"))]
-pub use self::bytebuf::{ByteBuf, ByteBufVisitor};
+pub use self::bytebuf::ByteBuf;
+
+#[cfg(any(feature = "std", feature = "collections"))]
+#[doc(hidden)] // does anybody need this?
+pub use self::bytebuf::ByteBufVisitor;
 
 #[cfg(feature = "collections")]
 use collections::Vec;
 
 ///////////////////////////////////////////////////////////////////////////////
 
-/// `Bytes` wraps a `&[u8]` in order to serialize into a byte array.
+/// Wraps a `&[u8]` in order to serialize in an efficient way. Does not support
+/// deserialization.
+///
+/// ```rust
+/// # #[macro_use] extern crate serde_derive;
+/// # extern crate serde;
+/// # use std::net::IpAddr;
+/// #
+/// use serde::bytes::Bytes;
+///
+/// # #[allow(dead_code)]
+/// #[derive(Serialize)]
+/// struct Packet<'a> {
+///     destination: IpAddr,
+///     payload: Bytes<'a>,
+/// }
+/// #
+/// # fn main() {}
+/// ```
 #[derive(Clone, Copy, Eq, Hash, PartialEq, PartialOrd, Ord)]
 pub struct Bytes<'a> {
     bytes: &'a [u8],
@@ -86,7 +124,25 @@ mod bytebuf {
     #[cfg(feature = "collections")]
     use collections::{String, Vec};
 
-    /// `ByteBuf` wraps a `Vec<u8>` and serializes as a byte array.
+    /// Wraps a `Vec<u8>` in order to serialize and deserialize in an efficient
+    /// way.
+    ///
+    /// ```rust
+    /// # #[macro_use] extern crate serde_derive;
+    /// # extern crate serde;
+    /// # use std::net::IpAddr;
+    /// #
+    /// use serde::bytes::ByteBuf;
+    ///
+    /// # #[allow(dead_code)]
+    /// #[derive(Serialize, Deserialize)]
+    /// struct Packet {
+    ///     destination: IpAddr,
+    ///     payload: ByteBuf,
+    /// }
+    /// #
+    /// # fn main() {}
+    /// ```
     #[derive(Clone, Default, Eq, Hash, PartialEq, PartialOrd, Ord)]
     pub struct ByteBuf {
         bytes: Vec<u8>,

serde/src/de/value.rs

@@ -975,16 +975,16 @@ mod private {
         }
 
         fn visit_tuple<V>(self,
-                        _len: usize,
+                          _len: usize,
-                        _visitor: V) -> Result<V::Value, Self::Error>
+                          _visitor: V) -> Result<V::Value, Self::Error>
             where V: de::Visitor
         {
             Err(de::Error::invalid_type(Unexpected::UnitVariant, &"tuple variant"))
         }
 
         fn visit_struct<V>(self,
-                        _fields: &'static [&'static str],
+                           _fields: &'static [&'static str],
-                        _visitor: V) -> Result<V::Value, Self::Error>
+                           _visitor: V) -> Result<V::Value, Self::Error>
             where V: de::Visitor
         {
             Err(de::Error::invalid_type(Unexpected::UnitVariant, &"struct variant"))

serde/src/lib.rs

@@ -1,13 +1,63 @@
-//! Serde Serialization Framework
+//! # Serde
 //!
-//! Serde is a powerful framework that enables serialization libraries to generically serialize
+//! Serde is a framework for ***ser***ializing and ***de***serializing Rust data
-//! Rust data structures without the overhead of runtime type information. In many situations, the
+//! structures efficiently and generically.
-//! handshake protocol between serializers and serializees can be completely optimized away,
-//! leaving serde to perform roughly the same speed as a hand written serializer for a specific
-//! type.
 //!
-//! For a detailed tutorial on the different ways to use serde please check out the
+//! The Serde ecosystem consists of data structures that know how to serialize
-//! [github repository](https://github.com/serde-rs/serde)
+//! and deserialize themselves along with data formats that know how to
+//! serialize and deserialize other things. Serde provides the layer by which
+//! these two groups interact with each other, allowing any supported data
+//! structure to be serialized and deserialized using any supported data format.
+//!
+//! See the Serde website https://serde.rs/ for additional documentation and
+//! usage examples.
+//!
+//! ### Design
+//!
+//! Where many other languages rely on runtime reflection for serializing data,
+//! Serde is instead built on Rust's powerful trait system. A data structure
+//! that knows how to serialize and deserialize itself is one that implements
+//! Serde's `Serialize` and `Deserialize` traits (or uses Serde's code
+//! generation to automatically derive implementations at compile time). This
+//! avoids any overhead of reflection or runtime type information. In fact in
+//! many situations the interaction between data structure and data format can
+//! be completely optimized away by the Rust compiler, leaving Serde
+//! serialization to perform roughly the same speed as a handwritten serializer
+//! for the specific selection of data structure and data format.
+//!
+//! ### Data formats
+//!
+//! The following is a partial list of data formats that have been implemented
+//! for Serde by the community.
+//!
+//! - [JSON](https://github.com/serde-rs/json), the ubiquitous JavaScript Object
+//!   Notation used by many HTTP APIs.
+//! - [Bincode](https://github.com/TyOverby/bincode), a compact binary format
+//!   used for IPC within the Servo rendering engine.
+//! - [CBOR](https://github.com/pyfisch/cbor), a Concise Binary Object
+//!   Representation designed for small message size without the need for
+//!   version negotiation.
+//! - [YAML](https://github.com/dtolnay/serde-yaml), a popular human-friendly
+//!   configuration language that ain't markup language.
+//! - [MessagePack](https://github.com/3Hren/msgpack-rust), an efficient binary
+//!   format that resembles a compact JSON.
+//! - [TOML](https://github.com/alexcrichton/toml-rs), a minimal configuration
+//!   format used by [Cargo](http://doc.crates.io/manifest.html).
+//! - [Pickle](https://github.com/birkenfeld/serde-pickle), a format common in
+//!   the Python world.
+//! - [Hjson](https://github.com/laktak/hjson-rust), a variant of JSON designed
+//!   to be readable and writable by humans.
+//! - [BSON](https://github.com/zonyitoo/bson-rs), the data storage and network
+//!   transfer format used by MongoDB.
+//! - [URL](https://github.com/nox/serde_urlencoded), the x-www-form-urlencoded
+//!   format.
+//! - [XML](https://github.com/serde-rs/xml), the flexible machine-friendly W3C
+//!   standard. *(deserialization only)*
+//! - [Envy](https://github.com/softprops/envy), a way to deserialize
+//!   environment variables into Rust structs. *(deserialization only)*
+//! - [Redis](https://github.com/OneSignal/serde-redis), deserialize values from
+//!   Redis when using [redis-rs](https://crates.io/crates/redis).
+//!   *(deserialization only)*
 
 #![doc(html_root_url="https://docs.serde.rs")]
 #![cfg_attr(not(feature = "std"), no_std)]
@@ -45,6 +95,7 @@ mod macros;
 pub mod bytes;
 pub mod de;
 #[cfg(feature = "std")]
+#[doc(hidden)]
 pub mod iter;
 pub mod ser;
 #[cfg_attr(feature = "std", doc(hidden))]

serde/src/macros.rs

@@ -124,28 +124,70 @@ macro_rules! forward_to_deserialize_helper {
     };
 }
 
-/// Helper to forward `Deserializer` methods to `Deserializer::deserialize`.
+// Super explicit first paragraph because this shows up at the top level and
-/// Every given method ignores all arguments and forwards to `deserialize`.
+// trips up people who are just looking for basic Serialize / Deserialize
-/// Note that `deserialize_enum` simply returns an `Error::invalid_type`; a
+// documentation.
-/// better approach is tracked in [serde-rs/serde#521][1].
+//
+/// Helper macro when implementing the `Deserializer` part of a new data format
+/// for Serde.
 ///
-/// ```rust,ignore
+/// Some `Deserializer` implementations for self-describing formats do not care
+/// what hint the `Visitor` gives them, they just want to blindly call the
+/// `Visitor` method corresponding to the data they can tell is in the input.
+/// This requires repetitive implementations of all the `Deserializer` trait
+/// methods.
+///
+/// ```rust
+/// # #[macro_use] extern crate serde;
+/// # use serde::de::{value, Deserializer, Visitor};
+/// # pub struct MyDeserializer;
+/// # impl Deserializer for MyDeserializer {
+/// #     type Error = value::Error;
+/// #     fn deserialize<V>(self, _: V) -> Result<V::Value, Self::Error>
+/// #         where V: Visitor
+/// #     { unimplemented!() }
+/// #
+/// #[inline]
+/// fn deserialize_bool<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+///     where V: Visitor
+/// {
+///     self.deserialize(visitor)
+/// }
+/// #     forward_to_deserialize! {
+/// #         usize u8 u16 u32 u64 isize i8 i16 i32 i64 f32 f64 char str string
+/// #         unit option seq seq_fixed_size bytes byte_buf map unit_struct
+/// #         newtype_struct tuple_struct struct struct_field tuple enum ignored_any
+/// #     }
+/// # }
+/// # fn main() {}
+/// ```
+///
+/// The `forward_to_deserialize!` macro implements these simple forwarding
+/// methods so that they forward directly to `Deserializer::deserialize`. You
+/// can choose which methods to forward.
+///
+/// ```rust
+/// # #[macro_use] extern crate serde;
+/// # use serde::de::{value, Deserializer, Visitor};
+/// # pub struct MyDeserializer;
 /// impl Deserializer for MyDeserializer {
+/// #   type Error = value::Error;
 ///     fn deserialize<V>(self, visitor: V) -> Result<V::Value, Self::Error>
 ///         where V: Visitor
 ///     {
 ///         /* ... */
+/// #       let _ = visitor;
+/// #       unimplemented!()
 ///     }
 ///
 ///     forward_to_deserialize! {
-///         bool usize u8 u16 u32 u64 isize i8 i16 i32 i64 f32 f64 char str string
+///         bool usize u8 u16 u32 u64 isize i8 i16 i32 i64 f32 f64 char str
-///         unit option seq seq_fixed_size bytes map unit_struct newtype_struct
+///         string unit option seq seq_fixed_size bytes byte_buf map unit_struct
-///         tuple_struct struct struct_field tuple enum ignored_any
+///         newtype_struct tuple_struct struct struct_field tuple enum ignored_any
 ///     }
 /// }
+/// # fn main() {}
 /// ```
-///
-/// [1]: https://github.com/serde-rs/serde/issues/521
 #[macro_export]
 macro_rules! forward_to_deserialize {
     ($($func:ident)*) => {

serde/src/ser/impls.rs

@@ -1,9 +1,3 @@
-//! Implementations for all of Rust's builtin types. Tuples implement the `Serialize` trait if they
-//! have at most 16 fields. Arrays implement the `Serialize` trait if their length is 32 or less.
-//! You can always forward array serialization to slice serialization, which works for any length.
-//! Long tuples are best replaced by tuple structs, for which you can use `derive(Serialize)`. In
-//! that case the number of fields is irrelevant.
-
 #[cfg(feature = "std")]
 use std::borrow::Cow;
 #[cfg(all(feature = "collections", not(feature = "std")))]
@@ -772,7 +766,7 @@ impl Serialize for path::Path {
     {
         match self.to_str() {
             Some(s) => s.serialize(serializer),
-            None => Err(Error::custom("Path contains invalid UTF-8 characters")),
+            None => Err(Error::custom("path contains invalid UTF-8 characters")),
         }
     }
 }

serde/src/ser/mod.rs

@@ -1,14 +1,97 @@
-//! Generic serialization framework.
+//! Generic data structure serialization framework.
-//! # For Developers who want to serialize objects
-//! Implement the `Serialize` trait for the type of objects you want to serialize. Call methods of
-//! the `serializer` object. For which methods to call and how to do so, look at the documentation
-//! of the `Serializer` trait.
 //!
-//! # For Serialization Format Developers
+//! The two most important traits in this module are `Serialize` and
-//! Implement the `Serializer` trait for a structure that contains fields that enable it to write
+//! `Serializer`.
-//! the serialization result to your target. When a method's argument is an object of type
+//!
-//! `Serialize`, you can either forward the serializer object (`self`) or create a new one,
+//!  - **A type that implements `Serialize` is a data structure** that can be
-//! depending on the quirks of your format.
+//!    serialized to any data format supported by Serde, and conversely
+//!  - **A type that implements `Serializer` is a data format** that can
+//!    serialize any data structure supported by Serde.
+//!
+//! # The Serialize trait
+//!
+//! Serde provides `Serialize` implementations for many Rust primitive and
+//! standard library types. The complete list is below. All of these can be
+//! serialized using Serde out of the box.
+//!
+//! Additionally, Serde provides a procedural macro called `serde_derive` to
+//! automatically generate `Serialize` implementations for structs and enums in
+//! your program. See the [codegen section of the manual][codegen] for how to
+//! use this.
+//!
+//! In rare cases it may be necessary to implement `Serialize` manually for some
+//! type in your program. See the [Implementing `Serialize`][impl-serialize]
+//! section of the manual for more about this.
+//!
+//! Third-party crates may provide `Serialize` implementations for types that
+//! they expose. For example the `linked-hash-map` crate provides a
+//! `LinkedHashMap<K, V>` type that is serializable by Serde because the crate
+//! provides an implementation of `Serialize` for it.
+//!
+//! # The Serializer trait
+//!
+//! `Serializer` implementations are provided by third-party crates, for example
+//! [`serde_json`][serde_json], [`serde_yaml`][serde_yaml] and
+//! [`bincode`][bincode].
+//!
+//! A partial list of well-maintained formats is given on the [Serde
+//! website][data-formats].
+//!
+//! # Implementations of Serialize provided by Serde
+//!
+//!  - **Primitive types**:
+//!    - bool
+//!    - isize, i8, i16, i32, i64
+//!    - usize, u8, u16, u32, u64
+//!    - f32, f64
+//!    - char
+//!    - str
+//!    - &T and &mut T
+//!  - **Compound types**:
+//!    - [T]
+//!    - [T; 0] through [T; 32]
+//!    - tuples up to size 16
+//!  - **Common standard library types**:
+//!    - String
+//!    - Option\<T\>
+//!    - Result\<T, E\>
+//!    - PhantomData\<T\>
+//!  - **Wrapper types**:
+//!    - Box\<T\>
+//!    - Rc\<T\>
+//!    - Arc\<T\>
+//!    - Cow\<'a, T\>
+//!  - **Collection types**:
+//!    - BTreeMap\<K, V\>
+//!    - BTreeSet\<T\>
+//!    - BinaryHeap\<T\>
+//!    - HashMap\<K, V, H\>
+//!    - HashSet\<T, H\>
+//!    - LinkedList\<T\>
+//!    - VecDeque\<T\>
+//!    - Vec\<T\>
+//!    - EnumSet\<T\> (unstable)
+//!    - Range\<T\> (unstable)
+//!    - RangeInclusive\<T\> (unstable)
+//!  - **Miscellaneous standard library types**:
+//!    - Duration
+//!    - Path
+//!    - PathBuf
+//!    - NonZero\<T\> (unstable)
+//!  - **Net types**:
+//!    - IpAddr
+//!    - Ipv4Addr
+//!    - Ipv6Addr
+//!    - SocketAddr
+//!    - SocketAddrV4
+//!    - SocketAddrV6
+//!
+//! [codegen]: https://serde.rs/codegen.html
+//! [impl-serialize]: https://serde.rs/impl-serialize.html
+//! [serde_json]: https://github.com/serde-rs/json
+//! [serde_yaml]: https://github.com/dtolnay/serde-yaml
+//! [bincode]: https://github.com/TyOverby/bincode
+//! [data-formats]: https://serde.rs/#data-formats
 
 #[cfg(feature = "std")]
 use std::error;
@@ -20,52 +103,146 @@ use core::cell::RefCell;
 
 use core::fmt::Display;
 
-pub mod impls;
+mod impls;
 
 ///////////////////////////////////////////////////////////////////////////////
 
-/// `Error` is a trait that allows a `Serialize` to generically create a
+/// Trait used by `Serialize` implementations to generically construct errors
-/// `Serializer` error.
+/// belonging to the `Serializer` against which they are currently running.
 pub trait Error: Sized + error::Error {
-    /// Raised when there is a general error when serializing a type.
+    /// Raised when a `Serialize` implementation encounters a general error
+    /// while serializing a type.
+    ///
+    /// The message should not be capitalized and should not end with a period.
+    ///
+    /// For example, a filesystem `Path` may refuse to serialize itself if it
+    /// contains invalid UTF-8 data.
+    ///
+    /// ```rust
+    /// # use serde::ser::{Serialize, Serializer, Error};
+    /// # struct Path;
+    /// # impl Path { fn to_str(&self) -> Option<&str> { unimplemented!() } }
+    /// impl Serialize for Path {
+    ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    ///         where S: Serializer
+    ///     {
+    ///         match self.to_str() {
+    ///             Some(s) => s.serialize(serializer),
+    ///             None => Err(Error::custom("path contains invalid UTF-8 characters")),
+    ///         }
+    ///     }
+    /// }
+    /// ```
     fn custom<T: Display>(msg: T) -> Self;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
-/// A trait that describes a type that can be serialized by a `Serializer`.
+/// An implementation of this trait is a **data structure** that can be
+/// serialized into any data format supported by Serde.
+///
+/// Serde provides `Serialize` implementations for many Rust primitive and
+/// standard library types. The complete list is [here][ser]. All of these can
+/// be serialized using Serde out of the box.
+///
+/// Additionally, Serde provides a procedural macro called `serde_derive` to
+/// automatically generate `Serialize` implementations for structs and enums in
+/// your program. See the [codegen section of the manual][codegen] for how to
+/// use this.
+///
+/// In rare cases it may be necessary to implement `Serialize` manually for some
+/// type in your program. See the [Implementing `Serialize`][impl-serialize]
+/// section of the manual for more about this.
+///
+/// Third-party crates may provide `Serialize` implementations for types that
+/// they expose. For example the `linked-hash-map` crate provides a
+/// `LinkedHashMap<K, V>` type that is serializable by Serde because the crate
+/// provides an implementation of `Serialize` for it.
+///
+/// [ser]: https://docs.serde.rs/serde/ser/index.html
+/// [codegen]: https://serde.rs/codegen.html
+/// [impl-serialize]: https://serde.rs/impl-serialize.html
 pub trait Serialize {
-    /// Serializes this value into this serializer.
+    /// Serialize this value into the given Serde serializer.
+    ///
+    /// See the [Implementing `Serialize`][impl-serialize] section of the manual
+    /// for more information about how to implement this method.
+    ///
+    /// [impl-serialize]: https://serde.rs/impl-serialize.html
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
         where S: Serializer;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
-/// A trait that describes a type that can serialize a stream of values into the underlying format.
+/// An implementation of this trait is a **data format** that can serialize any
+/// data structure supported by Serde.
 ///
-/// # For `Serialize` Developers
+/// The role of this trait is to define the serialization half of the Serde data
-/// Non-aggregate types like integers and strings can be serialized directly by calling the
+/// model, which is a way to categorize every Rust data structure into one of 30
-/// appropriate function. For Aggregate types there's an initial `serialize_T` method that yields
+/// possible types. Each method of the `Serializer` trait corresponds to one of
-/// a State object that you should not interact with. For each part of the aggregate there's a
+/// the types of the data model.
-/// `serialize_T_elt` method that allows you to pass values or key/value pairs. The types of the
-/// values or the keys may change between calls, but the serialization format may not necessarily
-/// accept it. The `serialize_T_elt` method also takes a mutable reference to the state object.
-/// Make sure that you always use the same state object and only the state object that was returned
-/// by the `serialize_T` method. Finally, when your object is done, call the `serialize_T_end`
-/// method and pass the state object by value
 ///
-/// # For Serialization Format Developers
+/// Implementations of `Serialize` map themselves into this data model by
-/// If your format has different situations where it accepts different types, create a
+/// invoking exactly one of the `Serializer` methods.
-/// `Serializer` for each situation. You can create the sub-`Serializer` in one of the aggregate
+///
-/// `serialize_T` methods and return it as a state object. Remember to also set the corresponding
+/// The types that make up the Serde data model are:
-/// associated type `TState`. In the `serialize_T_elt` methods you will be given a mutable
+///
-/// reference to that state. You do not need to do any additional checks for the correctness of the
+///  - 15 primitive types:
-/// state object, as it is expected that the user will not modify it. Due to the generic nature
+///    - bool
-/// of the `Serialize` impls, modifying the object is impossible on stable Rust.
+///    - isize, i8, i16, i32, i64
+///    - usize, u8, u16, u32, u64
+///    - f32, f64
+///    - char
+///    - string
+///  - byte array - [u8]
+///  - option
+///    - either none or some value
+///  - unit
+///    - unit is the type of () in Rust
+///  - unit_struct
+///    - for example `struct Unit` or `PhantomData<T>`
+///  - unit_variant
+///    - the `E::A` and `E::B` in `enum E { A, B }`
+///  - newtype_struct
+///    - for example `struct Millimeters(u8)`
+///  - newtype_variant
+///    - the `E::N` in `enum E { N(u8) }`
+///  - seq
+///    - a dynamically sized sequence of values, for example `Vec<T>` or
+///      `HashSet<T>`
+///  - seq_fixed_size
+///    - a statically sized sequence of values for which the size will be known
+///      at deserialization time without looking at the serialized data, for
+///      example `[u64; 10]`
+///  - tuple
+///    - for example `(u8,)` or `(String, u64, Vec<T>)`
+///  - tuple_struct
+///    - for example `struct Rgb(u8, u8, u8)`
+///  - tuple_variant
+///    - the `E::T` in `enum E { T(u8, u8) }`
+///  - map
+///    - for example `BTreeMap<K, V>`
+///  - struct
+///    - a key-value pairing in which the keys will be known at deserialization
+///      time without looking at the serialized data, for example `struct S { r:
+///      u8, g: u8, b: u8 }`
+///  - struct_variant
+///    - the `E::S` in `enum E { S { r: u8, g: u8, b: u8 } }`
+///
+/// Many Serde serializers produce text or binary data as output, for example
+/// JSON or Bincode. This is not a requirement of the `Serializer` trait, and
+/// there are serializers that do not produce text or binary output. One example
+/// is the `serde_json::value::Serializer` (distinct from the main `serde_json`
+/// serializer) that produces a `serde_json::Value` data structure in memory as
+/// output.
 pub trait Serializer {
-    /// Trickery to enforce correct use of the `Serialize` trait. Every
+    /// The output type produced by this `Serializer` during successful
-    /// `Serializer` should set `Ok = ()`.
+    /// serialization. Most serializers that produce text or binary output
+    /// should set `Ok = ()` and serialize into an `io::Write` or buffer
+    /// contained within the `Serializer` instance. Serializers that build
+    /// in-memory data structures may be simplified by using `Ok` to propagate
+    /// the data structure around.
     type Ok;
 
     /// The error type when some error occurs during serialization.
@@ -99,75 +276,99 @@ pub trait Serializer {
     /// content of the struct variant.
     type SerializeStructVariant: SerializeStructVariant<Ok=Self::Ok, Error=Self::Error>;
 
-    /// Serializes a `bool` value.
+    /// Serialize a `bool` value.
     fn serialize_bool(self, v: bool) -> Result<Self::Ok, Self::Error>;
 
-    /// Serializes an `isize` value. If the format does not differentiate
+    /// Serialize an `isize` value.
-    /// between `isize` and `i64`, a reasonable implementation would be to cast
+    ///
-    /// the value to `i64` and forward to `serialize_i64`.
+    /// If the format does not differentiate between `isize` and `i64`, a
+    /// reasonable implementation would be to cast the value to `i64` and
+    /// forward to `serialize_i64`.
     fn serialize_isize(self, v: isize) -> Result<Self::Ok, Self::Error>;
 
-    /// Serializes an `i8` value. If the format does not differentiate between
+    /// Serialize an `i8` value.
-    /// `i8` and `i64`, a reasonable implementation would be to cast the value
+    ///
-    /// to `i64` and forward to `serialize_i64`.
+    /// If the format does not differentiate between `i8` and `i64`, a
+    /// reasonable implementation would be to cast the value to `i64` and
+    /// forward to `serialize_i64`.
     fn serialize_i8(self, v: i8) -> Result<Self::Ok, Self::Error>;
 
-    /// Serializes an `i16` value. If the format does not differentiate between
+    /// Serialize an `i16` value.
-    /// `i16` and `i64`, a reasonable implementation would be to cast the value
+    ///
-    /// to `i64` and forward to `serialize_i64`.
+    /// If the format does not differentiate between `i16` and `i64`, a
+    /// reasonable implementation would be to cast the value to `i64` and
+    /// forward to `serialize_i64`.
     fn serialize_i16(self, v: i16) -> Result<Self::Ok, Self::Error>;
 
-    /// Serializes an `i32` value. If the format does not differentiate between
+    /// Serialize an `i32` value.
-    /// `i32` and `i64`, a reasonable implementation would be to cast the value
+    ///
-    /// to `i64` and forward to `serialize_i64`.
+    /// If the format does not differentiate between `i32` and `i64`, a
+    /// reasonable implementation would be to cast the value to `i64` and
+    /// forward to `serialize_i64`.
     fn serialize_i32(self, v: i32) -> Result<Self::Ok, Self::Error>;
 
-    /// Serializes an `i64` value.
+    /// Serialize an `i64` value.
     fn serialize_i64(self, v: i64) -> Result<Self::Ok, Self::Error>;
 
-    /// Serializes a `usize` value. If the format does not differentiate between
+    /// Serialize a `usize` value.
-    /// `usize` and `u64`, a reasonable implementation would be to cast the
+    ///
-    /// value to `u64` and forward to `serialize_u64`.
+    /// If the format does not differentiate between `usize` and `u64`, a
+    /// reasonable implementation would be to cast the value to `u64` and
+    /// forward to `serialize_u64`.
     fn serialize_usize(self, v: usize) -> Result<Self::Ok, Self::Error>;
 
-    /// Serializes a `u8` value. If the format does not differentiate between
+    /// Serialize a `u8` value.
-    /// `u8` and `u64`, a reasonable implementation would be to cast the value
+    ///
-    /// to `u64` and forward to `serialize_u64`.
+    /// If the format does not differentiate between `u8` and `u64`, a
+    /// reasonable implementation would be to cast the value to `u64` and
+    /// forward to `serialize_u64`.
     fn serialize_u8(self, v: u8) -> Result<Self::Ok, Self::Error>;
 
-    /// Serializes a `u16` value. If the format does not differentiate between
+    /// Serialize a `u16` value.
-    /// `u16` and `u64`, a reasonable implementation would be to cast the value
+    ///
-    /// to `u64` and forward to `serialize_u64`.
+    /// If the format does not differentiate between `u16` and `u64`, a
+    /// reasonable implementation would be to cast the value to `u64` and
+    /// forward to `serialize_u64`.
     fn serialize_u16(self, v: u16) -> Result<Self::Ok, Self::Error>;
 
-    /// Serializes a `u32` value. If the format does not differentiate between
+    /// Serialize a `u32` value.
-    /// `u32` and `u64`, a reasonable implementation would be to cast the value
+    ///
-    /// to `u64` and forward to `serialize_u64`.
+    /// If the format does not differentiate between `u32` and `u64`, a
+    /// reasonable implementation would be to cast the value to `u64` and
+    /// forward to `serialize_u64`.
     fn serialize_u32(self, v: u32) -> Result<Self::Ok, Self::Error>;
 
-    /// `Serializes a `u64` value.
+    /// Serialize a `u64` value.
     fn serialize_u64(self, v: u64) -> Result<Self::Ok, Self::Error>;
 
-    /// Serializes an `f32` value. If the format does not differentiate between
+    /// Serialize an `f32` value.
-    /// `f32` and `f64`, a reasonable implementation would be to cast the value
+    ///
-    /// to `f64` and forward to `serialize_f64`.
+    /// If the format does not differentiate between `f32` and `f64`, a
+    /// reasonable implementation would be to cast the value to `f64` and
+    /// forward to `serialize_f64`.
     fn serialize_f32(self, v: f32) -> Result<Self::Ok, Self::Error>;
 
-    /// Serializes an `f64` value.
+    /// Serialize an `f64` value.
     fn serialize_f64(self, v: f64) -> Result<Self::Ok, Self::Error>;
 
-    /// Serializes a character. If the format does not support characters,
+    /// Serialize a character.
-    /// it is reasonable to serialize it as a single element `str` or a `u32`.
+    ///
+    /// If the format does not support characters, it is reasonable to serialize
+    /// it as a single element `str` or a `u32`.
     fn serialize_char(self, v: char) -> Result<Self::Ok, Self::Error>;
 
-    /// Serializes a `&str`.
+    /// Serialize a `&str`.
     fn serialize_str(self, value: &str) -> Result<Self::Ok, Self::Error>;
 
+    /// Serialize a chunk of raw byte data.
+    ///
     /// Enables serializers to serialize byte slices more compactly or more
     /// efficiently than other types of slices. If no efficient implementation
     /// is available, a reasonable implementation would be to forward to
-    /// `serialize_seq`. If forwarded, the implementation looks usually just like this:
+    /// `serialize_seq`. If forwarded, the implementation looks usually just
-    /// ```rust
+    /// like this:
+    ///
+    /// ```rust,ignore
     /// let mut seq = self.serialize_seq(Some(value.len()))?;
     /// for b in value {
     ///     seq.serialize_element(b)?;
@@ -176,19 +377,40 @@ pub trait Serializer {
     /// ```
     fn serialize_bytes(self, value: &[u8]) -> Result<Self::Ok, Self::Error>;
 
-    /// Serializes a `()` value. It's reasonable to just not serialize anything.
+    /// Serialize a `None` value.
+    fn serialize_none(self) -> Result<Self::Ok, Self::Error>;
+
+    /// Serialize a `Some(T)` value.
+    fn serialize_some<T: ?Sized + Serialize>(
+        self,
+        value: &T,
+    ) -> Result<Self::Ok, Self::Error>;
+
+    /// Serialize a `()` value.
     fn serialize_unit(self) -> Result<Self::Ok, Self::Error>;
 
-    /// Serializes a unit struct value. A reasonable implementation would be to
+    /// Serialize a unit struct like `struct Unit` or `PhantomData<T>`.
-    /// forward to `serialize_unit`.
+    ///
+    /// A reasonable implementation would be to forward to `serialize_unit`.
     fn serialize_unit_struct(
         self,
         name: &'static str,
     ) -> Result<Self::Ok, Self::Error>;
 
-    /// Serializes a unit variant, otherwise known as a variant with no
+    /// Serialize a unit variant like `E::A` in `enum E { A, B }`.
-    /// arguments. A reasonable implementation would be to forward to
+    ///
-    /// `serialize_unit`.
+    /// The `name` is the name of the enum, the `variant_index` is the index of
+    /// this variant within the enum, and the `variant` is the name of the
+    /// variant.
+    ///
+    /// A reasonable implementation would be to forward to `serialize_unit`.
+    ///
+    /// ```rust,ignore
+    /// match *self {
+    ///     E::A => serializer.serialize_unit_variant("E", 0, "A"),
+    ///     E::B => serializer.serialize_unit_variant("E", 1, "B"),
+    /// }
+    /// ```
     fn serialize_unit_variant(
         self,
         name: &'static str,
@@ -196,19 +418,32 @@ pub trait Serializer {
         variant: &'static str,
     ) -> Result<Self::Ok, Self::Error>;
 
-    /// Allows a tuple struct with a single element, also known as a newtype
+    /// Serialize a newtype struct like `struct Millimeters(u8)`.
-    /// struct, to be more efficiently serialized than a tuple struct with
+    ///
-    /// multiple items. A reasonable implementation would be to forward to
+    /// Serializers are encouraged to treat newtype structs as insignificant
-    /// `serialize_tuple_struct` or to just serialize the inner value without wrapping.
+    /// wrappers around the data they contain. A reasonable implementation would
+    /// be to forward to `value.serialize(self)`.
+    ///
+    /// ```rust,ignore
+    /// serializer.serialize_newtype_struct("Millimeters", &self.0)
+    /// ```
     fn serialize_newtype_struct<T: ?Sized + Serialize>(
         self,
         name: &'static str,
         value: &T,
     ) -> Result<Self::Ok, Self::Error>;
 
-    /// Allows a variant with a single item to be more efficiently serialized
+    /// Serialize a newtype variant like `E::N` in `enum E { N(u8) }`.
-    /// than a variant with multiple items. A reasonable implementation would be
+    ///
-    /// to forward to `serialize_tuple_variant`.
+    /// The `name` is the name of the enum, the `variant_index` is the index of
+    /// this variant within the enum, and the `variant` is the name of the
+    /// variant. The `value` is the data contained within this newtype variant.
+    ///
+    /// ```rust,ignore
+    /// match *self {
+    ///     E::N(ref n) => serializer.serialize_newtype_variant("E", 0, "N", n),
+    /// }
+    /// ```
     fn serialize_newtype_variant<T: ?Sized + Serialize>(
         self,
         name: &'static str,
@@ -217,53 +452,96 @@ pub trait Serializer {
         value: &T,
     ) -> Result<Self::Ok, Self::Error>;
 
-    /// Serializes a `None` value.
+    /// Begin to serialize a dynamically sized sequence. This call must be
-    fn serialize_none(self) -> Result<Self::Ok, Self::Error>;
+    /// followed by zero or more calls to `serialize_element`, then a call to
-
+    /// `end`.
-    /// Serializes a `Some(...)` value.
+    ///
-    fn serialize_some<T: ?Sized + Serialize>(
+    /// The argument is the number of elements in the sequence, which may or may
-        self,
+    /// not be computable before the sequence is iterated. Some serializers only
-        value: &T,
+    /// support sequences whose length is known up front.
-    ) -> Result<Self::Ok, Self::Error>;
+    ///
-
+    /// ```rust,ignore
-    /// Begins to serialize a sequence. This call must be followed by zero or
+    /// let mut seq = serializer.serialize_seq(Some(self.len()))?;
-    /// more calls to `serialize_seq_elt`, then a call to `serialize_seq_end`.
+    /// for element in self {
+    ///     seq.serialize_element(element)?;
+    /// }
+    /// seq.end()
+    /// ```
     fn serialize_seq(
         self,
         len: Option<usize>,
     ) -> Result<Self::SerializeSeq, Self::Error>;
 
-    /// Begins to serialize a sequence whose length will be known at
+    /// Begin to serialize a statically sized sequence whose length will be
-    /// deserialization time. This call must be followed by zero or more calls
+    /// known at deserialization time without looking at the serialized data.
-    /// to `serialize_seq_elt`, then a call to `serialize_seq_end`. A reasonable
+    /// This call must be followed by zero or more calls to `serialize_element`,
-    /// implementation would be to forward to `serialize_seq`.
+    /// then a call to `end`.
+    ///
+    /// ```rust,ignore
+    /// let mut seq = serializer.serialize_seq_fixed_size(self.len())?;
+    /// for element in self {
+    ///     seq.serialize_element(element)?;
+    /// }
+    /// seq.end()
+    /// ```
     fn serialize_seq_fixed_size(
         self,
         size: usize,
     ) -> Result<Self::SerializeSeq, Self::Error>;
 
-    /// Begins to serialize a tuple. This call must be followed by zero or more
+    /// Begin to serialize a tuple. This call must be followed by zero or more
-    /// calls to `serialize_tuple_elt`, then a call to `serialize_tuple_end`. A
+    /// calls to `serialize_field`, then a call to `end`.
-    /// reasonable implementation would be to forward to `serialize_seq`.
+    ///
+    /// ```rust,ignore
+    /// let mut tup = serializer.serialize_tuple(3)?;
+    /// tup.serialize_field(&self.0)?;
+    /// tup.serialize_field(&self.1)?;
+    /// tup.serialize_field(&self.2)?;
+    /// tup.end()
+    /// ```
     fn serialize_tuple(
         self,
         len: usize,
     ) -> Result<Self::SerializeTuple, Self::Error>;
 
-    /// Begins to serialize a tuple struct. This call must be followed by zero
+    /// Begin to serialize a tuple struct like `struct Rgb(u8, u8, u8)`. This
-    /// or more calls to `serialize_tuple_struct_elt`, then a call to
+    /// call must be followed by zero or more calls to `serialize_field`, then a
-    /// `serialize_tuple_struct_end`. A reasonable implementation would be to
+    /// call to `end`.
-    /// forward to `serialize_tuple`.
+    ///
+    /// The `name` is the name of the tuple struct and the `len` is the number
+    /// of data fields that will be serialized.
+    ///
+    /// ```rust,ignore
+    /// let mut ts = serializer.serialize_tuple_struct("Rgb", 3)?;
+    /// ts.serialize_field(&self.0)?;
+    /// ts.serialize_field(&self.1)?;
+    /// ts.serialize_field(&self.2)?;
+    /// ts.end()
+    /// ```
     fn serialize_tuple_struct(
         self,
         name: &'static str,
         len: usize,
     ) -> Result<Self::SerializeTupleStruct, Self::Error>;
 
-    /// Begins to serialize a tuple variant. This call must be followed by zero
+    /// Begin to serialize a tuple variant like `E::T` in `enum E { T(u8, u8)
-    /// or more calls to `serialize_tuple_variant_elt`, then a call to
+    /// }`. This call must be followed by zero or more calls to
-    /// `serialize_tuple_variant_end`. A reasonable implementation would be to
+    /// `serialize_field`, then a call to `end`.
-    /// forward to `serialize_tuple_struct`.
+    ///
+    /// The `name` is the name of the enum, the `variant_index` is the index of
+    /// this variant within the enum, the `variant` is the name of the variant,
+    /// and the `len` is the number of data fields that will be serialized.
+    ///
+    /// ```rust,ignore
+    /// match *self {
+    ///     E::T(ref a, ref b) => {
+    ///         let mut tv = serializer.serialize_tuple_variant("E", 0, "T", 2)?;
+    ///         tv.serialize_field(a)?;
+    ///         tv.serialize_field(b)?;
+    ///         tv.end()
+    ///     }
+    /// }
+    /// ```
     fn serialize_tuple_variant(
         self,
         name: &'static str,
@@ -272,25 +550,65 @@ pub trait Serializer {
         len: usize,
     ) -> Result<Self::SerializeTupleVariant, Self::Error>;
 
-    /// Begins to serialize a map. This call must be followed by zero or more
+    /// Begin to serialize a map. This call must be followed by zero or more
-    /// calls to `serialize_map_key` and `serialize_map_value`, then a call to
+    /// calls to `serialize_key` and `serialize_value`, then a call to `end`.
-    /// `serialize_map_end`.
+    ///
+    /// The argument is the number of elements in the map, which may or may not
+    /// be computable before the map is iterated. Some serializers only support
+    /// maps whose length is known up front.
+    ///
+    /// ```rust,ignore
+    /// let mut map = serializer.serialize_map(Some(self.len()))?;
+    /// for (k, v) in self {
+    ///     map.serialize_key(k)?;
+    ///     map.serialize_value(v)?;
+    /// }
+    /// map.end()
+    /// ```
     fn serialize_map(
         self,
         len: Option<usize>,
     ) -> Result<Self::SerializeMap, Self::Error>;
 
-    /// Begins to serialize a struct. This call must be followed by zero or more
+    /// Begin to serialize a struct like `struct Rgb { r: u8, g: u8, b: u8 }`.
-    /// calls to `serialize_struct_elt`, then a call to `serialize_struct_end`.
+    /// This call must be followed by zero or more calls to `serialize_field`,
+    /// then a call to `end`.
+    ///
+    /// The `name` is the name of the struct and the `len` is the number of
+    /// data fields that will be serialized.
+    ///
+    /// ```rust,ignore
+    /// let mut struc = serializer.serialize_struct("Rgb", 3)?;
+    /// struc.serialize_field("r", &self.r)?;
+    /// struc.serialize_field("g", &self.g)?;
+    /// struc.serialize_field("b", &self.b)?;
+    /// struc.end()
+    /// ```
     fn serialize_struct(
         self,
         name: &'static str,
         len: usize,
     ) -> Result<Self::SerializeStruct, Self::Error>;
 
-    /// Begins to serialize a struct variant. This call must be followed by zero
+    /// Begin to serialize a struct variant like `E::S` in `enum E { S { r: u8,
-    /// or more calls to `serialize_struct_variant_elt`, then a call to
+    /// g: u8, b: u8 } }`. This call must be followed by zero or more calls to
-    /// `serialize_struct_variant_end`.
+    /// `serialize_field`, then a call to `end`.
+    ///
+    /// The `name` is the name of the enum, the `variant_index` is the index of
+    /// this variant within the enum, the `variant` is the name of the variant,
+    /// and the `len` is the number of data fields that will be serialized.
+    ///
+    /// ```rust,ignore
+    /// match *self {
+    ///     E::S { ref r, ref g, ref b } => {
+    ///         let mut sv = serializer.serialize_struct_variant("E", 0, "S", 3)?;
+    ///         sv.serialize_field("r", r)?;
+    ///         sv.serialize_field("g", g)?;
+    ///         sv.serialize_field("b", b)?;
+    ///         sv.end()
+    ///     }
+    /// }
+    /// ```
     fn serialize_struct_variant(
         self,
         name: &'static str,
@@ -302,76 +620,115 @@ pub trait Serializer {
 
 /// Returned from `Serializer::serialize_seq` and
 /// `Serializer::serialize_seq_fixed_size`.
+///
+/// ```rust,ignore
+/// let mut seq = serializer.serialize_seq(Some(self.len()))?;
+/// for element in self {
+///     seq.serialize_element(element)?;
+/// }
+/// seq.end()
+/// ```
 pub trait SerializeSeq {
-    /// Trickery to enforce correct use of the `Serialize` trait. Every
+    /// Must match the `Ok` type of our `Serializer`.
-    /// `SerializeSeq` should set `Ok = ()`.
     type Ok;
 
-    /// The error type when some error occurs during serialization.
+    /// Must match the `Error` type of our `Serializer`.
     type Error: Error;
 
-    /// Serializes a sequence element.
+    /// Serialize a sequence element.
     fn serialize_element<T: ?Sized + Serialize>(&mut self, value: &T) -> Result<(), Self::Error>;
 
-    /// Finishes serializing a sequence.
+    /// Finish serializing a sequence.
     fn end(self) -> Result<Self::Ok, Self::Error>;
 }
 
 /// Returned from `Serializer::serialize_tuple`.
+///
+/// ```rust,ignore
+/// let mut tup = serializer.serialize_tuple(3)?;
+/// tup.serialize_field(&self.0)?;
+/// tup.serialize_field(&self.1)?;
+/// tup.serialize_field(&self.2)?;
+/// tup.end()
+/// ```
 pub trait SerializeTuple {
-    /// Trickery to enforce correct use of the `Serialize` trait. Every
+    /// Must match the `Ok` type of our `Serializer`.
-    /// `SerializeTuple` should set `Ok = ()`.
     type Ok;
 
-    /// The error type when some error occurs during serialization.
+    /// Must match the `Error` type of our `Serializer`.
     type Error: Error;
 
-    /// Serializes a tuple element.
+    /// Serialize a tuple element.
     fn serialize_element<T: ?Sized + Serialize>(&mut self, value: &T) -> Result<(), Self::Error>;
 
-    /// Finishes serializing a tuple.
+    /// Finish serializing a tuple.
     fn end(self) -> Result<Self::Ok, Self::Error>;
 }
 
 /// Returned from `Serializer::serialize_tuple_struct`.
+///
+/// ```rust,ignore
+/// let mut ts = serializer.serialize_tuple_struct("Rgb", 3)?;
+/// ts.serialize_field(&self.0)?;
+/// ts.serialize_field(&self.1)?;
+/// ts.serialize_field(&self.2)?;
+/// ts.end()
+/// ```
 pub trait SerializeTupleStruct {
-    /// Trickery to enforce correct use of the `Serialize` trait. Every
+    /// Must match the `Ok` type of our `Serializer`.
-    /// `SerializeTupleStruct` should set `Ok = ()`.
     type Ok;
 
-    /// The error type when some error occurs during serialization.
+    /// Must match the `Error` type of our `Serializer`.
     type Error: Error;
 
-    /// Serializes a tuple struct element.
+    /// Serialize a tuple struct field.
     fn serialize_field<T: ?Sized + Serialize>(&mut self, value: &T) -> Result<(), Self::Error>;
 
-    /// Finishes serializing a tuple struct.
+    /// Finish serializing a tuple struct.
     fn end(self) -> Result<Self::Ok, Self::Error>;
 }
 
 /// Returned from `Serializer::serialize_tuple_variant`.
+///
+/// ```rust,ignore
+/// match *self {
+///     E::T(ref a, ref b) => {
+///         let mut tv = serializer.serialize_tuple_variant("E", 0, "T", 2)?;
+///         tv.serialize_field(a)?;
+///         tv.serialize_field(b)?;
+///         tv.end()
+///     }
+/// }
+/// ```
 pub trait SerializeTupleVariant {
-    /// Trickery to enforce correct use of the `Serialize` trait. Every
+    /// Must match the `Ok` type of our `Serializer`.
-    /// `SerializeTupleVariant` should set `Ok = ()`.
     type Ok;
 
-    /// The error type when some error occurs during serialization.
+    /// Must match the `Error` type of our `Serializer`.
     type Error: Error;
 
-    /// Serializes a tuple variant element.
+    /// Serialize a tuple variant field.
     fn serialize_field<T: ?Sized + Serialize>(&mut self, value: &T) -> Result<(), Self::Error>;
 
-    /// Finishes serializing a tuple variant.
+    /// Finish serializing a tuple variant.
     fn end(self) -> Result<Self::Ok, Self::Error>;
 }
 
 /// Returned from `Serializer::serialize_map`.
+///
+/// ```rust,ignore
+/// let mut map = serializer.serialize_map(Some(self.len()))?;
+/// for (k, v) in self {
+///     map.serialize_key(k)?;
+///     map.serialize_value(v)?;
+/// }
+/// map.end()
+/// ```
 pub trait SerializeMap {
-    /// Trickery to enforce correct use of the `Serialize` trait. Every
+    /// Must match the `Ok` type of our `Serializer`.
-    /// `SerializeMap` should set `Ok = ()`.
     type Ok;
 
-    /// The error type when some error occurs during serialization.
+    /// Must match the `Error` type of our `Serializer`.
     type Error: Error;
 
     /// Serialize a map key.
@@ -380,52 +737,71 @@ pub trait SerializeMap {
     /// Serialize a map value.
     fn serialize_value<T: ?Sized + Serialize>(&mut self, value: &T) -> Result<(), Self::Error>;
 
-    /// Finishes serializing a map.
+    /// Finish serializing a map.
     fn end(self) -> Result<Self::Ok, Self::Error>;
 }
 
 /// Returned from `Serializer::serialize_struct`.
+///
+/// ```rust,ignore
+/// let mut struc = serializer.serialize_struct("Rgb", 3)?;
+/// struc.serialize_field("r", &self.r)?;
+/// struc.serialize_field("g", &self.g)?;
+/// struc.serialize_field("b", &self.b)?;
+/// struc.end()
+/// ```
 pub trait SerializeStruct {
-    /// Trickery to enforce correct use of the `Serialize` trait. Every
+    /// Must match the `Ok` type of our `Serializer`.
-    /// `SerializeStruct` should set `Ok = ()`.
     type Ok;
 
-    /// The error type when some error occurs during serialization.
+    /// Must match the `Error` type of our `Serializer`.
     type Error: Error;
 
-    /// Serializes a struct field.
+    /// Serialize a struct field.
     fn serialize_field<T: ?Sized + Serialize>(&mut self, key: &'static str, value: &T) -> Result<(), Self::Error>;
 
-    /// Finishes serializing a struct.
+    /// Finish serializing a struct.
     fn end(self) -> Result<Self::Ok, Self::Error>;
 }
 
 /// Returned from `Serializer::serialize_struct_variant`.
+///
+/// ```rust,ignore
+/// match *self {
+///     E::S { ref r, ref g, ref b } => {
+///         let mut sv = serializer.serialize_struct_variant("E", 0, "S", 3)?;
+///         sv.serialize_field("r", r)?;
+///         sv.serialize_field("g", g)?;
+///         sv.serialize_field("b", b)?;
+///         sv.end()
+///     }
+/// }
+/// ```
 pub trait SerializeStructVariant {
-    /// Trickery to enforce correct use of the `Serialize` trait. Every
+    /// Must match the `Ok` type of our `Serializer`.
-    /// `SerializeStructVariant` should set `Ok = ()`.
     type Ok;
 
-    /// The error type when some error occurs during serialization.
+    /// Must match the `Error` type of our `Serializer`.
     type Error: Error;
 
-    /// Serialize a struct variant element.
+    /// Serialize a struct variant field.
     fn serialize_field<T: ?Sized + Serialize>(&mut self, key: &'static str, value: &T) -> Result<(), Self::Error>;
 
-    /// Finishes serializing a struct variant.
+    /// Finish serializing a struct variant.
     fn end(self) -> Result<Self::Ok, Self::Error>;
 }
 
-/// A wrapper type for iterators that implements `Serialize` for iterators whose items implement
+/// A wrapper type for iterators that implements `Serialize` for iterators whose
-/// `Serialize`. Don't use multiple times. Create new versions of this with the `iterator` function
+/// items implement `Serialize`. Don't use multiple times. Create new versions
-/// every time you want to serialize an iterator.
+/// of this with the `serde::ser::iterator` function every time you want to
+/// serialize an iterator.
 #[cfg(feature = "unstable")]
 pub struct Iterator<I>(RefCell<Option<I>>)
     where <I as IntoIterator>::Item: Serialize,
           I: IntoIterator;
 
-/// Creates a temporary type that can be passed to any function expecting a `Serialize` and will
+/// Create a wrapper type that can be passed to any function expecting a
-/// serialize the given iterator as a sequence
+/// `Serialize` and will serialize the given iterator as a sequence.
 #[cfg(feature = "unstable")]
 pub fn iterator<I>(iter: I) -> Iterator<I>
     where <I as IntoIterator>::Item: Serialize,

testing/tests/test_ser.rs

@@ -432,7 +432,7 @@ fn test_cannot_serialize_paths() {
     assert_ser_tokens_error(
         &Path::new(path),
         &[],
-        Error::Message("Path contains invalid UTF-8 characters".to_owned()));
+        Error::Message("path contains invalid UTF-8 characters".to_owned()));
 
     let mut path_buf = PathBuf::new();
     path_buf.push(path);
@@ -440,7 +440,7 @@ fn test_cannot_serialize_paths() {
     assert_ser_tokens_error(
         &path_buf,
         &[],
-        Error::Message("Path contains invalid UTF-8 characters".to_owned()));
+        Error::Message("path contains invalid UTF-8 characters".to_owned()));
 }
 
 #[test]