From c702c5eff26d3bdb371db90ebf0f79b6e152b687 Mon Sep 17 00:00:00 2001
From: Alex Orlenko <zxteam@protonmail.com>
Date: Mon, 21 Jun 2021 20:28:14 +0100
Subject: [PATCH] Add userdata example

---
 Cargo.toml           |  4 ++++
 examples/userdata.rs | 45 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+)
 create mode 100644 examples/userdata.rs

diff --git a/Cargo.toml b/Cargo.toml
index 5d7175b..2c40a2e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -97,3 +97,7 @@ required-features = ["macros"]
 [[example]]
 name = "serialize"
 required-features = ["serialize"]
+
+[[example]]
+name = "userdata"
+required-features = ["macros"]
diff --git a/examples/userdata.rs b/examples/userdata.rs
new file mode 100644
index 0000000..8823dfd
--- /dev/null
+++ b/examples/userdata.rs
@@ -0,0 +1,45 @@
+use mlua::{chunk, Lua, MetaMethod, Result, UserData};
+
+#[derive(Default)]
+struct Rectangle {
+    length: u32,
+    width: u32,
+}
+
+impl UserData for Rectangle {
+    fn add_fields<'lua, F: mlua::UserDataFields<'lua, Self>>(fields: &mut F) {
+        fields.add_field_method_get("length", |_, this| Ok(this.length));
+        fields.add_field_method_set("length", |_, this, val| {
+            this.length = val;
+            Ok(())
+        });
+        fields.add_field_method_get("width", |_, this| Ok(this.width));
+        fields.add_field_method_set("width", |_, this, val| {
+            this.width = val;
+            Ok(())
+        });
+    }
+
+    fn add_methods<'lua, M: mlua::UserDataMethods<'lua, Self>>(methods: &mut M) {
+        methods.add_method("area", |_, this, ()| Ok(this.length * this.width));
+        methods.add_method("diagonal", |_, this, ()| {
+            Ok((this.length.pow(2) as f64 + this.width.pow(2) as f64).sqrt())
+        });
+
+        // Constructor
+        methods.add_meta_function(MetaMethod::Call, |_, ()| Ok(Rectangle::default()));
+    }
+}
+
+fn main() -> Result<()> {
+    let lua = Lua::new();
+    let rectangle = Rectangle::default();
+    lua.load(chunk! {
+        local rect = $rectangle()
+        rect.width = 10
+        rect.length = 5
+        assert(rect:area() == 50)
+        assert(rect:diagonal() - 11.1803 < 0.0001)
+    })
+    .exec()
+}