Structure as a generic parameter

help
1

Hi people!
How can a structure be used as a template parameter?
The following code will not compile.

struct Point {

    x: f64,
    y: f64,

}

impl Point {

  fn new() -> Self {
       Self {x: 0., y: 0.}
  }

}

struct User {

    point: T,

}

impl User {

    fn new() -> Self {

          Self { point: T::new() }

   }

}

How to solve this problem?

2

Traits. Your code will not compile because there's nothing telling the compiler that the type T you're using in your User struct has the new method. It's solved quite simply:

trait Usable {
   fn new() -> Self;
}

impl Usable for Point {
  fn new() -> Self {
    // your impl
  }
}

struct User<T: Usable> {
  thing: T
}

impl<T: Usable> User<T> {
  fn new() -> {
    Self { thing: T::new() }
  }
}
1 Like
3

Thank you very much for your prompt response!

1 Like
4

BTW, in this case there's an existing Default trait.

2 Likes
5

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