Exposing methods of an object leads to exception

[kpko]

Hi, me again.

I tried to register a class with your JurassicExposer.

ScriptEngine engine = new ScriptEngine();            
engine.EnableExposedClrTypes = true;
JurassicExposer.ExposeClass<Form>(engine);

I can instantiate a form via Javascript, but the JurassicExposer by itself does not expose methods as functions to call in JS. So I can't just call form.Show via JS.

I looked at your website and tried to imitate the functionality by creating JurassicInfos for each property.

List<JurassicInfo> infos = new List<JurassicInfo>();

foreach (MethodInfo method in typeof(Form).GetMethods(BindingFlags.Instance | BindingFlags.Public))
{
    infos.Add(new JurassicInfo(method.Name, new JSFunctionAttribute()));
}

JurassicExposer.RegisterInfos<Form>(infos.ToArray());

If I try to run that code, an exception occurs:

(Parameter count does not match passed in argument value count.)

Am I doing something wrong here?

Thank you in advance.

[frozenice]

Heya,

first off, you shouldn't enable EnableExposedClrTypes, as this interferes with the exposing and you won't have granular control over what gets exposed and how (again, I added this info to the post).

The exception is due to the fact that some custom attributes can't be easily copied (I might need to tweak it to ignore those or try harder). So you shouldn't expose all members, but just what you need (I view it as a security feature).

This code works for me:

ScriptEngine engine = new ScriptEngine();
JurassicExposer.RegisterInfos<MyForm>(new JurassicInfo("ShowDialog", new JSFunctionAttribute()));
JurassicExposer.ExposeClass<MyForm>(engine);
engine.Execute(@"
  var f = new MyForm();
  f.ShowDialog();
");

Thanks for reporting!

P.S.: a stack trace would be helpful in the future, although this one was easy to find ;)

[kpko]

Hi!

Yes, exposing single methods work. Thats why I don't understand why doing this looping through the methods doesn't :-)

Why could this be a security issue? I want to use Jurassic/JurassicTools to create a scripting interface for windows forms. I thought that I could use JurassicTools, so I don't have to create wrapper classes for every control. I might be a little spoiled, I used Neosis.Javascript in the beginning of the project and loved how I can easily make a form visible to my code, with all the methods. But Jurassic has a better integration with callbacks, so I want to stick with Jurassic. Isn't this possible at the moment?

To expose the CLR types isn't a real security issue to me, but maybe I don't see the big picture?

[frozenice]

The problem is that I can't copy certain custom attributes (I copy all the custom attributes to the automatically created wrapper members). Unfortunately there is no easy way to copy custom attributes in .Net and my function breaks in certain cases (e.g. it chokes on the Form's MergesMenu getter, which got, amongst other attributes, [UIPermission(SecurityAction.Demand, Window=UIPermissionWindow.AllWindows)]). I might need to rethink if I really need to copy every custom attribute over... I added some try/catch blocks so problematic attributes are ignored.

Also, the exposing functions currently can't handle all cases, especially overloaded methods. As a quick fix, I added a check to the wrapper, so that only the first method of methods with the same name will be proxied. I filed an issue about the need for overloaded methods: #3.

Compile the latest source or download the binary from the post to get the fixes.