Add back explanatory comment about trying "return <expr>" before statement

Also run through rustfmt

examples/examples.rs

@@ -70,7 +70,8 @@ fn examples() -> LuaResult<()> {
         for k, v in pairs(map_table) do
             print(k, v)
         end
-        "#, None
+        "#,
+        None,
     )?;
 
     // You can load lua functions
@@ -118,14 +119,14 @@ fn examples() -> LuaResult<()> {
     assert_eq!(
         lua.eval::<bool>(
             r#"check_equal({"a", "b", "c"}, {"a", "b", "c"})"#,
-            None
+            None,
         )?,
         true
     );
     assert_eq!(
         lua.eval::<bool>(
             r#"check_equal({"a", "b", "c"}, {"d", "e", "f"})"#,
-            None
+            None,
         )?,
         false
     );
@@ -158,7 +159,12 @@ fn examples() -> LuaResult<()> {
     });
     globals.set("vec2", vec2_constructor)?;
 
-    assert!(lua.eval::<f32>("(vec2(1, 2) + vec2(2, 2)):magnitude()", None)? - 5.0 < f32::EPSILON);
+    assert!(
+        lua.eval::<f32>(
+            "(vec2(1, 2) + vec2(2, 2)):magnitude()",
+            None,
+        )? - 5.0 < f32::EPSILON
+    );
 
     Ok(())
 }

src/lua.rs

@@ -1087,8 +1087,11 @@ impl Lua {
     pub fn eval<'lua, R: FromLuaMulti<'lua>>(
         &'lua self,
         source: &str,
-        name: Option<&str>
+        name: Option<&str>,
     ) -> LuaResult<R> {
+        // First, try interpreting the lua as an expression by adding
+        // "return", then as a statement.  This is the same thing the
+        // actual lua repl does.
         self.load(&format!("return {}", source), name)
             .or_else(|_| self.load(source, name))?
             .call(())

src/tests.rs

@@ -323,8 +323,18 @@ fn test_metamethods() {
     let globals = lua.globals();
     globals.set("userdata1", UserData(7)).unwrap();
     globals.set("userdata2", UserData(3)).unwrap();
-    assert_eq!(lua.eval::<UserData>("userdata1 + userdata2", None).unwrap().0, 10);
-    assert_eq!(lua.eval::<UserData>("userdata1 - userdata2", None).unwrap().0, 4);
+    assert_eq!(
+        lua.eval::<UserData>("userdata1 + userdata2", None)
+            .unwrap()
+            .0,
+        10
+    );
+    assert_eq!(
+        lua.eval::<UserData>("userdata1 - userdata2", None)
+            .unwrap()
+            .0,
+        4
+    );
     assert_eq!(lua.eval::<i64>("userdata1:get()", None).unwrap(), 7);
     assert_eq!(lua.eval::<i64>("userdata2.inner", None).unwrap(), 3);
     assert!(lua.eval::<()>("userdata2.nonexist_field", None).is_err());
@@ -610,7 +620,7 @@ fn test_thread() {
                     return sum
                 end
             "#,
-            None
+            None,
         ).unwrap(),
     );
 
@@ -635,7 +645,7 @@ fn test_thread() {
                     end
                 end
             "#,
-            None
+            None,
         ).unwrap(),
     );
 
@@ -655,7 +665,7 @@ fn test_thread() {
                 end
             end)
         "#,
-        None
+        None,
     ).unwrap();
     assert_eq!(thread.status(), LuaThreadStatus::Active);
     assert_eq!(thread.resume::<_, i64>(()).unwrap(), 42);
@@ -669,7 +679,7 @@ fn test_thread() {
                 return 987
             end)
         "#,
-        None
+        None,
     ).unwrap();
 
     assert_eq!(thread.resume::<_, u32>(42).unwrap(), 123);