How do I implement a struct that takes a generic vector with lifetime annotations?

Question

The following compiles fine:

pub struct Reader<'a> {
    position: uint,
    data: &'a [u8]
}

It's a reader that takes a vector (actually a slice) of type u8 as a reference, and I specify the lifetime.

However this is not exactly what I want. I want to be able to make the struct generic, and to be even more precise, I want to denote that the type should be a slice of anything. I tried this for starters:

pub struct Reader<'a, T> {
    position: uint,
    data: &'a T
}

It does not denote T to be a slice, but this is already failing with a message:

the parameter type T may not live long enough; consider adding an explicit lifetime bound T:'a...

Ok so I just had to specify the lifetime.

But now my problem is that how do I make it generic of type slice and have the lifetime? I tried things like Reader<'a, T: 'a Vec> and T: 'a [T] but I have no idea how I am supposed to denote this and the official guide does not seem to deal with a case like this.

I simply want to construct a Reader that takes in any type of slice by borrowing it, and provides methods to operate on the data (in read-only ways).

Answer 1

After trying a bit more, I finally figured it out:

pub struct Reader<'a, T: 'a> {
    position: uint,
    data: &'a [T]
}

This defines the reader's data to be of type Slice<T> ([] denotes the slice) and &'a specifies the lifetime for the borrowed data.

Now I can implement stuff like this:

impl<'a, T> Reader<'a, T> {
    pub fn from_data(bytes: &'a[T]) -> Reader<'a, T> {
        Reader {
            position: 0,
            data: bytes
        }
    }
}