Retrieve modified variable value

Question

I have an IronRuby script that modifies the value of a variable set via the ScriptScope.

I'd like to retrieve the value of the variable after it's been modified, but I get the old value.

This is the code I have:

var engine = Ruby.CreateEngine();
var scope = engine.Runtime.CreateScope();

scope.SetVariable("y", 11);

var source = engine.CreateScriptSourceFromString("y=33; puts y;", SourceCodeKind.Statements);
source.Execute(scope);

The above code executes and outputs 33 to the console, which is OK.

However, I tried adding the following line after the above code:

Console.WriteLine(scope.GetVariable("y"));

and it outputs 11, which is the original value.

Is there a way to get the new variable value?

Answer 1

With IronPython, to retrieve a value, I use a proxy object like this.

public class ScriptProxy
{
    private int _result;

    public int Result
    {
        get { return this._result; }
        set { this._result = value; }
    }
}

And I call SetVariable to pass an instance of the ScriptObject :

ScriptEngine pyEngine = Python.CreateEngine();
ScriptScope pyScope = pyEngine.CreateScope();

ScriptProxy proxy = new ScriptProxy();
pyScope.SetVariable("proxy", proxy);

In your script you can set the result :

proxy.Result=33;

Answer 2

Setvariable is to change inputs

e.g.

if you had y = y + 1

Before the DLR you would have made your script 'y = 11' followed by 'y = y + 1' and if you then wanted to run it again for y = 15, you would have built a new script initialising y to 15 and then it would have been interpreted again.

What's happening is y = 33 is getting replaced by y = 11, setvariable is so you can use the same compiled script for different inputs