closes #101

src/internal/js/class.rs

@@ -212,7 +212,7 @@ pub trait Class: Managed + Any {
     }
 }
 
-impl<T: Class> This for T {
+unsafe impl<T: Class> This for T {
     fn as_this(h: raw::Local) -> Self {
         Self::from_raw(h)
     }

src/internal/js/mod.rs

@@ -102,7 +102,7 @@ impl ValueInternal for JsValue {
     }
 }
 
-impl This for JsValue {
+unsafe impl This for JsValue {
     fn as_this(h: raw::Local) -> Self {
         JsValue(h)
     }
@@ -154,7 +154,7 @@ impl Managed for JsUndefined {
     fn from_raw(h: raw::Local) -> Self { JsUndefined(h) }
 }
 
-impl This for JsUndefined {
+unsafe impl This for JsUndefined {
     fn as_this(_: raw::Local) -> Self {
         unsafe {
             let mut local: raw::Local = mem::zeroed();
@@ -499,7 +499,7 @@ impl Managed for JsObject {
     fn from_raw(h: raw::Local) -> Self { JsObject(h) }
 }
 
-impl This for JsObject {
+unsafe impl This for JsObject {
     fn as_this(h: raw::Local) -> Self { JsObject(h) }
 }
 

src/internal/vm.rs

@@ -199,7 +199,8 @@ extern "C" fn module_callback<'a>(kernel: fn(Module) -> VmResult<()>, exports: H
     });
 }
 
-pub trait This: Managed {
+/// A type that may be the type of a function's `this` binding.
+pub unsafe trait This: Managed {
     fn as_this(h: raw::Local) -> Self;
 }
 

src/vm.rs

@@ -1,3 +1,3 @@
 //! Abstractions representing the JavaScript virtual machine and its control flow.
 
-pub use internal::vm::{Call, FunctionCall, Arguments, Module, Throw, VmResult, JsResult, Lock};
+pub use internal::vm::{Call, FunctionCall, This, Arguments, Module, Throw, VmResult, JsResult, Lock};

tests/lib/functions.js

@@ -17,4 +17,8 @@ describe('JsFunction', function() {
   it('new a JsFunction', function () {
     assert.equal(addon.construct_js_function(Date), 1970);
   });
+
+  it('got two parameters, a string and a number', function() {
+    addon.check_string_and_number("string", 42);
+  });
 });

tests/native/src/js/functions.rs

@@ -1,6 +1,6 @@
-use neon::vm::{Call, JsResult};
+use neon::vm::{Call, JsResult, This, FunctionCall};
 use neon::mem::Handle;
-use neon::js::{JsNumber, JsNull, JsFunction, Object, JsValue};
+use neon::js::{JsNumber, JsNull, JsFunction, Object, JsValue, JsUndefined, JsString, Value};
 
 fn add1(call: Call) -> JsResult<JsNumber> {
     let scope = call.scope;
@@ -28,3 +28,19 @@ pub fn construct_js_function(call: Call) -> JsResult<JsNumber> {
     let args: Vec<Handle<JsValue>> = vec![];
     try!(get_utc_full_year_method.call(scope, o.upcast::<JsValue>(), args)).check::<JsNumber>()
 }
+
+trait CheckArgument<'a> {
+    fn check_argument<V: Value>(&mut self, i: i32) -> JsResult<'a, V>;
+}
+
+impl<'a, T: This> CheckArgument<'a> for FunctionCall<'a, T> {
+    fn check_argument<V: Value>(&mut self, i: i32) -> JsResult<'a, V> {
+        try!(self.arguments.require(self.scope, i)).check::<V>()
+    }
+}
+
+pub fn check_string_and_number(mut call: Call) -> JsResult<JsUndefined> {
+    let x = try!(call.check_argument::<JsString>(0));
+    let y = try!(call.check_argument::<JsNumber>(1));
+    Ok(JsUndefined::new())
+}

tests/native/src/lib.rs

@@ -46,6 +46,8 @@ register_module!(m, {
     try!(m.export("call_js_function", call_js_function));
     try!(m.export("construct_js_function", construct_js_function));
 
+    try!(m.export("check_string_and_number", check_string_and_number));
+
     let class: Handle<JsClass<JsUser>> = try!(JsUser::class(m.scope));
     let constructor: Handle<JsFunction<JsUser>> = try!(class.constructor(m.scope));
     try!(m.exports.set("User", constructor));