CODEWITHSUNDEEP
genericsrusttraits
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Reputation: 414

Traits for both Cloneable types and Copyable types

I've been writing a fairly simple raster image trait system, but I was also wanting to extend it to work for comma-separated values, and it seems more natural to allow the trait for both pixels (which would have the Copy trait), and String (which does not).

However, overloading for both causes conflicts. So how would one go about writing a trait which accepts both Copyable types and Cloneable types?

Currently the working definition looks like 

impl<T:Grid2d,V:Copy> drawable for Line2d{
   fn stroke(&self,out:&mut T);
}

This works fine for pixels which are basically integers.

Upvotes: 2

Views: 70

Answers (1)

Francis Gagn&#233;
Francis Gagn&#233;

Reputation: 65937

Copy is a subtrait of Clone (i.e. all Copy types are also Clone), so you could have a single impl with a bound on Clone and it will also accept all Copy types.

impl<T: Grid2d, V: Clone> Drawable for Line2d {
   fn stroke(&self, out: &mut T);
}

You'll have to explicitly call .clone() to get a copy of the value, but for Copy types, this .clone() call should be very cheap (and in release builds, it's likely to be inlined).

Upvotes: 4

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