impl Pancake {
fn as_circle(&self) -> &Circle { &self.circle }
fn as_mut_circle(&mut self) -> &mut Circle { &mut self.circle }
}
The compiler will optimize trivial functions, except cross-crate. In those
cases, use an #[inline] annotation.
On Thu, Oct 16, 2014 at 10:57 PM, David Henningsson <di...@ubuntu.com>
wrote:
> This is probably a previously asked question, but I couldn't find it on
> Google, so...
> Let's extend the Circle example from the guide a little:
> struct Circle {
> x:f64,
> y:f64,
> radius:f64,
> }
> trait HasArea {
> fn area(&self)-> f64;
> }
> impl HasArea for Circle {
> fn area(&self)-> f64 {
> std::f64::consts::PI * (self.radius * self.radius)
> }
> }
> struct Pancake {
> circle: Circle,
> is_tasty: bool,
> }
> ...now, what is the easiest way I can implement HasArea for Pancake? I
> could do this:
> impl HasArea for Pancake {
> fn area(&self) -> f64 { self.circle.area() }
> }
> ...but that means a lot of boiler-plate code, especially if HasArea has
> many methods. Hopefully rust will just inline/optimise the redirection
> away in most cases to avoid the runtime cost, but is there a smarter or
> more idiomatic way of doing this?
> // David
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