struct Foo([f64, ..3]);
impl<I: Int> Index<I, f64> for Foo {
fn index(&self, index: &I) -> f64 {
let index = index.to_uint().unwrap();
match self {
&Foo(ref v) => v[index].clone()
}
}
}
fn main() {
let tmp : uint = 0;
let foo = Foo([1.0, 2.0, 3.0]);
println!("{:?}", foo[tmp]);
}
On 9 Jan 2014, at 2:08 pm, Ashish Myles <[email protected]> wrote:
> The following implementation of Index for Foo works fine.
>
> struct Foo([f64, ..3]);
> impl Index<uint, f64> for Foo {
> fn index(&self, index: &uint) -> f64 {
> match self {
> &Foo(ref v) => v[*index].clone()
> }
> }
> }
> fn main() {
> let tmp : uint = 0;
> let foo = Foo([1.0, 2.0, 3.0]);
> println!("{:?}", foo[tmp]);
> }
>
> But if tmp is of type int, then I get an int-uint type mismatch failure. So I
> tried the following.
>
> use std::num::Int;
> ...
> impl<Idx : Int> Index<Idx, f64> for Foo {
> fn index(&self, index: &Idx) -> f64 {
> match self {
> &Foo(ref v) => v[*index].clone()
> }
> }
> }
>
> But I get
> error: mismatched types: expected integral type but found `Idx`
> with the error pointing at *index above. What's the right way to go about
> implementing generic operator indexing? Or does one always require
> conversion to uint (in the first case above) on the caller's side?
>
> Ashish
> _______________________________________________
> Rust-dev mailing list
> [email protected]
> https://mail.mozilla.org/listinfo/rust-dev
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