Possible Bug in Chapter 3.3?

[seemawn1981]

Hi,
I am studying the book, and in Chapter 3.3, the code after "if you are savvy..." leads to this:

#[component]
fn ProgressBar(
    #[prop(default = 100)] max: u16,
    progress: impl Fn() -> i32 + Send + Sync + 'static,
) -> impl IntoView {
    view! {
        <progress
            max=max
            value=progress
        />
        // Add a line-break to avoid overlap
        <br/>
    }
}
#[component]
fn App() -> impl IntoView {
    let (count, set_count) = signal(0);
    // Defining the closure that accesses the signal
    let double_count = move || count.get() * 2;
    view! {
        <button
            on:click=move |_| {
                set_count.update(|n| *n +=1 );
            }
            >
            "Click me"
        </button>
        // Progress Bar with Signal
        <ProgressBar progress = count> // <--- Fails here
        <ProgressBar progress = double_count/>
    }
}

Trunk serve fails to compile because "expected an Fn() closure, found leptos::prelude::ReadSignal<{integer}>"
To make sure that I was not mistaken, I just copied and pasted the code for the progress bar (the upper component in the listing above)

Most propably I had done something wrong, but maybe, there is a glitch in this chapter. Could you please have a look?

Edit: I formerly pasted a piece of Code, where I bound the type impl FnOnce() -> i32 to the variable double count. This was a attempt to troubleshoot this issue. Sorry for that.

Thanks

Simon

[gbj]

This only works on nightly, where signals directly implement the Fn() traits. The book was later rewritten to default to stable-only features. This probably just needs to be reworded now to clarify that this only works on nightly.

[seemawn1981]

ah, that explains a lot. Yeah, that would be great, as I prefer stable Rust, as long it is possible to drive Leptos with stable features.

Besides: Rust 2024 has been released shortly, so I thougt, that some of the nightly features are merged to stable right now, aren't they?

Thanks a lot!