Higher Order Components

There are several cases where Struct components do not directly support a feature (ex. Suspense) or require a lot of boilerplate code to use the features (ex. Context).

In those cases, it is recommended to create function components that are higher-order components.

Higher Order Components Definition

Higher Order Components are components that do not add any new HTML and only wrap some other components to provide extra functionality.

Example

Hook into Context and pass it down to a struct component

use yew::prelude::*;

#[derive(Clone, Debug, PartialEq)]
struct Theme {
    foreground: String,
    background: String,
}

#[function_component]
pub fn App() -> Html {
    let ctx = use_state(|| Theme {
        foreground: "#000000".to_owned(),
        background: "#eeeeee".to_owned(),
    });

    html! {
        <ContextProvider<Theme> context={(*ctx).clone()}>
            <ThemedButtonHOC />
        </ContextProvider<Theme>>
    }
}

#[function_component]
pub fn ThemedButtonHOC() -> Html {
    let theme = use_context::<Theme>().expect("no ctx found");

    html! {<ThemedButtonStructComponent {theme} />}
}

#[derive(Properties, PartialEq)]
pub struct Props {
    pub theme: Theme,
}

struct ThemedButtonStructComponent;

impl Component for ThemedButtonStructComponent {
    type Message = ();
    type Properties = Props;

    fn create(_ctx: &Context<Self>) -> Self {
        Self
    }

    fn view(&self, ctx: &Context<Self>) -> Html {
        let theme = &ctx.props().theme;
        html! {
            <button style={format!(
                    "background: {}; color: {};",
                    theme.background,
                    theme.foreground
                )}
            >
                { "Click me!" }
            </button>
        }
    }
}