CODEWITHSUNDEEP
rust
user11321136
user11321136

Reputation:

How to call function from certain trait explicitly?

I'd like to know how to call a function from a trait providing that there are several traits with the same function names.

The problem is in the 33 line or tr1::tr(v);

How I have to express which trait I want to call?

struct V2D {
  x: i32,
  y: i32
}

impl V2D {
  fn new(x: i32, y: i32) -> V2D {
    V2D { x, y }
  }
}

trait tr1 {
  fn tr();
}

trait tr2 {
  fn tr();
}

impl tr1 for V2D {
  fn tr() {
    println!("This is tr1");
  }
}

impl tr2 for V2D {
  fn tr() {
    println!("This is tr2");
  }
}

fn main() {
  let v = V2D::new(1,2);
  tr1::tr(v);
}

Upvotes: 2

Views: 968

Answers (2)

yorodm
yorodm

Reputation: 4461

The simplest way would be using fully qualified syntax. In your case tr is an associated function so all you need is a little typecasting:

fn main() {
  let v = V2D::new(1,2);
  <V2D as tr1>::tr();
  <V2D as tr2>::tr();
}

The syntax for methods on the other hand would be something like this:

struct V2D {
  x: i32,
  y: i32
}

impl V2D {
  fn new(x: i32, y: i32) -> V2D {
    V2D{x,y}
  }
}

trait tr1 {
  fn tr(&self);
}

trait tr2 {
  fn tr(&self);
}

impl tr1 for V2D {
  fn tr(&self) {
    println!("This is tr1");
  }
}
impl tr2 for V2D {
  fn tr(&self) {
    println!("This is tr2");
  }
}

fn main() {
  let v = V2D::new(1,2);
  tr1::tr(&v);
}

Upvotes: 1

mcarton
mcarton

Reputation: 30001

The syntax you have used (tr1::tr(v)) would be correct if your method took has a self parameter (Permalink to the playground), but if it doesn't, you need to call it on the type specifying the type and trait explicitly:

<V2D as tr1>::tr()

(Permalink to the playground)

Upvotes: 2

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