From ffd48e4cdbb0e0892a4b67d0bbdafb4b37569540 Mon Sep 17 00:00:00 2001
From: Alexander Baranov <baranovas@vtb.ru>
Date: Sun, 24 May 2026 11:39:21 +0300
Subject: [PATCH] =?UTF-8?q?smart-house-web:=20leptos=20=D1=8D=D1=81=D0=BF?=
 =?UTF-8?q?=D0=B5=D1=80=D0=B8=D0=BC=D0=B5=D0=BD=D1=82=D1=8B?=
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---
 smart-house-web/frontend/src/main.rs | 145 +++++++++++++++++++--------
 1 file changed, 105 insertions(+), 40 deletions(-)

diff --git a/smart-house-web/frontend/src/main.rs b/smart-house-web/frontend/src/main.rs
index d7c5702..57c11e5 100644
--- a/smart-house-web/frontend/src/main.rs
+++ b/smart-house-web/frontend/src/main.rs
@@ -1,49 +1,114 @@
 #![allow(non_snake_case)]
-use leptos::prelude::*;
+
+use leptos::{ev::MouseEvent, prelude::*};
+
+// This highlights four different ways that child components can communicate
+// with their parent:
+// 1) <ButtonA/>: passing a WriteSignal as one of the child component props,
+//    for the child component to write into and the parent to read
+// 2) <ButtonB/>: passing a closure as one of the child component props, for
+//    the child component to call
+// 3) <ButtonC/>: adding an `on:` event listener to a component
+// 4) <ButtonD/>: providing a context that is used in the component (rather than prop drilling)
+
+#[derive(Copy, Clone)]
+struct SmallcapsContext(WriteSignal<bool>);
 
 #[component]
-fn App() -> impl IntoView {
-    let (value, set_value) = signal(Ok(0));
+pub fn App() -> impl IntoView {
+    // just some signals to toggle four classes on our <p>
+    let (red, set_red) = signal(false);
+    let (right, set_right) = signal(false);
+    let (italics, set_italics) = signal(false);
+    let (smallcaps, set_smallcaps) = signal(false);
+
+    // the newtype pattern isn't *necessary* here but is a good practice
+    // it avoids confusion with other possible future `WriteSignal<bool>` contexts
+    // and makes it easier to refer to it in ButtonD
+    provide_context(SmallcapsContext(set_smallcaps));
 
     view! {
-        <h1>"Error Handling"</h1>
-        <label>
-            "Type a number (or something that's not a number!)"
-            <input type="number" on:input:target=move |ev| {
-                // when input changes, try to parse a number from the input
-                set_value.set(ev.target().value().parse::<i32>())
-            }/>
-            // If an `Err(_) had been rendered inside the <ErrorBoundary/>,
-            // the fallback will be displayed. Otherwise, the children of the
-            // <ErrorBoundary/> will be displayed.
-            <ErrorBoundary
-                // the fallback receives a signal containing current errors
-                fallback=|errors| view! {
-                    <div class="error">
-                        <p>"Not a number! Errors: "</p>
-                        // we can render a list of errors
-                        // as strings, if we'd like
-                        <ul>
-                            {move || errors.get()
-                                .into_iter()
-                                .map(|(_, e)| view! { <li>{e.to_string()}</li>})
-                                .collect::<Vec<_>>()
-                            }
-                        </ul>
-                    </div>
-                }
+        <main>
+            <p
+                // class: attributes take F: Fn() => bool, and these signals all implement Fn()
+                class:red=red
+                class:right=right
+                class:italics=italics
+                class:smallcaps=smallcaps
             >
-                <p>
-                    "You entered "
-                    // because `value` is `Result<i32, _>`,
-                    // it will render the `i32` if it is `Ok`,
-                    // and render nothing and trigger the error boundary
-                    // if it is `Err`. It's a signal, so this will dynamically
-                    // update when `value` changes
-                    <strong>{value}</strong>
-                </p>
-            </ErrorBoundary>
-        </label>
+                "Lorem ipsum sit dolor amet."
+            </p>
+
+            // Button A: pass the signal setter
+            <ButtonA setter=set_red/>
+
+            // Button B: pass a closure
+            <ButtonB on_click=move |_| set_right.update(|value| *value = !*value)/>
+
+            // Button C: use a regular event listener
+            // setting an event listener on a component like this applies it
+            // to each of the top-level elements the component returns
+            <ButtonC on:click=move |_| set_italics.update(|value| *value = !*value)/>
+
+            // Button D gets its setter from context rather than props
+            <ButtonD/>
+        </main>
+    }
+}
+
+/// Button A receives a signal setter and updates the signal itself
+#[component]
+pub fn ButtonA(
+    /// Signal that will be toggled when the button is clicked.
+    setter: WriteSignal<bool>,
+) -> impl IntoView {
+    view! {
+        <button
+            on:click=move |_| setter.update(|value| *value = !*value)
+        >
+            "Toggle Red"
+        </button>
+    }
+}
+
+/// Button B receives a closure
+#[component]
+pub fn ButtonB(
+    /// Callback that will be invoked when the button is clicked.
+    on_click: impl FnMut(MouseEvent) + 'static,
+) -> impl IntoView {
+    view! {
+        <button
+            on:click=on_click
+        >
+            "Toggle Right"
+        </button>
+    }
+}
+
+/// Button C is a dummy: it renders a button but doesn't handle
+/// its click. Instead, the parent component adds an event listener.
+#[component]
+pub fn ButtonC() -> impl IntoView {
+    view! {
+        <button>
+            "Toggle Italics"
+        </button>
+    }
+}
+
+/// Button D is very similar to Button A, but instead of passing the setter as a prop
+/// we get it from the context
+#[component]
+pub fn ButtonD() -> impl IntoView {
+    let setter = use_context::<SmallcapsContext>().unwrap().0;
+
+    view! {
+        <button
+            on:click=move |_| setter.update(|value| *value = !*value)
+        >
+            "Toggle Small Caps"
+        </button>
     }
 }