# [`Read`](https://doc.rust-lang.org/std/io/trait.Read.html)
When deriving for enum like the following:
```rust
#[derive(Read)]
enum Enum<A, B> {
A(A),
B(B),
}
```
Code like this will be generated:
```rust
enum Enum<A, B> {
A(A),
B(B),
}
impl<A, B> ::std::io::Read for Enum<A, B>
where
A: ::std::io::Read,
B: ::std::io::Read,
{
#[inline]
fn read(&mut self, buf: &mut [u8]) -> ::std::io::Result<usize> {
match self {
Enum::A(x) => ::std::io::Read::read(x, buf),
Enum::B(x) => ::std::io::Read::read(x, buf),
}
}
#[inline]
fn read_to_end(&mut self, buf: &mut ::std::vec::Vec<u8>) -> ::std::io::Result<usize> {
match self {
Enum::A(x) => ::std::io::Read::read_to_end(x, buf),
Enum::B(x) => ::std::io::Read::read_to_end(x, buf),
}
}
#[inline]
fn read_to_string(&mut self, buf: &mut ::std::string::String) -> ::std::io::Result<usize> {
match self {
Enum::A(x) => ::std::io::Read::read_to_string(x, buf),
Enum::B(x) => ::std::io::Read::read_to_string(x, buf),
}
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> ::std::io::Result<()> {
match self {
Enum::A(x) => ::std::io::Read::read_exact(x, buf),
Enum::B(x) => ::std::io::Read::read_exact(x, buf),
}
}
}
```