docs: add refcell_view example

examples/refcell_view.rs

@@ -0,0 +1,39 @@
+extern crate cursive;
+
+use cursive::Cursive;
+use cursive::view::{Boxable, Identifiable};
+use cursive::views::{LinearLayout, EditView, TextView, Dialog};
+
+fn main() {
+    let mut siv = Cursive::new();
+
+    // Create a dialog with 2 edit fields, and a text view.
+    // The text view indicates when the 2 fields content match.
+    siv.add_layer(Dialog::around(LinearLayout::vertical()
+            .child(EditView::new().on_edit(on_edit).with_id_mut("1"))
+            .child(EditView::new().on_edit(on_edit).with_id_mut("2"))
+            .child(TextView::new("match").with_id_mut("match"))
+            .fixed_width(10))
+        .button("Quit", Cursive::quit));
+
+    siv.run();
+}
+
+// Compare the content of the two edit views,
+// and update the TextView accordingly.
+//
+// We'll ignore the `content` and `cursor` arguments,
+// and directly retrieve the content from the `Cursive` root.
+fn on_edit(siv: &mut Cursive, _content: &str, _cursor: usize) {
+    // Get handles for each view.
+    let edit_1 = siv.find_id_mut::<EditView>("1").unwrap();
+    let edit_2 = siv.find_id_mut::<EditView>("2").unwrap();
+    let mut text = siv.find_id_mut::<TextView>("match").unwrap();
+
+    // Directly compare references to edit_1 and edit_2.
+    text.set_content(if edit_1.get_content() == edit_2.get_content() {
+        "match"
+    } else {
+        "no match"
+    });
+}