CODEWITHSUNDEEP
rust
Vahe
Vahe

Reputation: 149

trait type mismatch resolving `<Button as Render>::Props == AppProps`

I have a trait, and I have 2 structures that implement this trait. they must have their own properties. So I used the associated type. But enum requires determining the value of the associated type.the render method must return a View. I define a type.everything works fine until I decide to include the component in the rendering method. I get an error

error[E0271]: type mismatch resolving `<Button as Render>::Props == AppProps`
  --> src/lib.rs:39:17
   |
39 | /                 Box::new(
40 | |                     Button::create(
41 | |                         ButtonProps {}
42 | |                     )
43 | |                 )
   | |_________________^ expected struct `AppProps`, found struct `ButtonProps`
   |
   = note: required for the cast to the object type `dyn Render<Props = AppProps>`

pub enum View<T> {
    View(Vec<View<T>>),
    Render(Box<Render<Props = T>>),
}

pub trait Render {
    type Props;
    fn render(&self) -> View<Self::Props>;
    fn create(props: Self::Props) -> Self
    where
        Self: Sized;
}

// -------- Button -----------

struct Button { props: ButtonProps }
struct ButtonProps { }

impl Render for Button {
    type Props = ButtonProps;
    fn create(props: Self::Props) -> Self {
        Button { props }
    }
    fn render(&self) -> View<Self::Props> {
        View::View(vec![])
    }
}

// -------- App ------------

struct App { props: AppProps }
struct AppProps {}

impl Render for App {
    type Props = AppProps;
    fn render(&self) -> View<Self::Props> {
        View::View(vec![
            View::Render(
                Box::new(
                    Button::create(
                        ButtonProps {}
                    )
                )
            )
        ])
    }
    fn create(props: Self::Props) -> Self {
        App { props }
    }
}

I think the compiler tells me, think of another method for returning and storing components. But I wonder if there is any way to overcome this problem. Thank you in advance. https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=d6cde99cb9deffcf911cbcb9d1229e46

update

pub trait Render<P> {
    //type Props;
    fn render(&self) -> View;
    fn create(props: P) -> Self
    where
        Self: Sized;
}

impl Render<Props> for App

this option works

Upvotes: 0

Views: 105

Answers (1)

Vahe
Vahe

Reputation: 149

It seems like i should remove both the associated type and the constructor from the trait, and let configuration and construction be an ordinary method.

Upvotes: 0

Related Questions