Le 21 avr. 2014 à 12:57, Artella Coding <[email protected]> a écrit
:
>
> Suppose I have the enum :
>
> enum Coll<T> {
> A(f64,T),
> B(f64,T)
> }
>
> I know that the compiler can automatically derive the Clone trait for the
> above. However I would like to manually implement it and was unsuccessful in
> my attempt. I tried the following :
>
> enum Coll<T> {
> A(f64,T),
> B(f64,T)
> }
>
> impl<T: Clone> Clone for Coll<T> {
> fn clone (&self) -> Coll<T> {
> match *self {
> A(x,y) => A(x,y.clone()),
> B(x,y) => B(x,y.clone())
> }
> }
> }
The error is in your match statement. You try to bind the "T" part of your type
to the "y" variable, which causes by default a by-value binding.
Since you can't know statically if T has value or move semantics, you can't do
this, since in the case of move semantics, this would move the T out of self,
that you don't own because you take it as a reference (&self).
You have instead to explicitly bind T by ref :
match *self {
A(x, ref y) => A(x ,y.clone()),
B(x, ref y) => B(x, y.clone())
}
Leo
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