Disabled first-chance-exception but debugger stopps within try...catch when using IronPython

Question

The following code should be executed without stopping the debugger:

var engine = Python.CreateEngine(AppDomain.CurrentDomain);
var source = engine.CreateScriptSourceFromString("Foo.Do()");
var compiledCode = source.Compile(new PythonCompilerOptions { Optimized = true });

try
{
    compiledCode.Execute(
         engine.CreateScope(
            new Dictionary<string, object> { 
                                            { "Foo", new Foo() }
                                           }));

    MessageBox.Show("Executed without error");
}
catch (Exception ex)
{
    MessageBox.Show(string.Format("Error at execution: {0}", ex.Message));
}

Using this class:

public class Foo
{
    public void Do()
    {
        throw new InvalidOperationException("The debugger should not break here...");
    }
}

The script execution runs in a try-block to handle any exception. If I have code like 1 / 0 all works perfekt. The exception is created in Python (or in the engine) and my catch-block is called as expected without forcing the debugger to stop anywhere.

Calling try { new Foo().Do(); } catch {} in C# does also work without stopping the debugger.

But throwing an exception in C#-code that's invoked in python will force the debugger to stop at the throw new...-line.

I don't want the debugger to stop there.

I disabled the first-chance-exceptions in Debug/Exceptions but the debugger still stops at throw.

I can't use DebuggerStepThrough because in my working code the exception it not thrown in this method but deeper in the code. The code is also used out of C# and decorating all these methods with DebuggerStepThrough will make my C# debugger obsolete.

A solution is to disable User-unhandled exceptions in Debug/Exceptions too but I want to break at exceptions that aren't handled by the user so this is not an option.

What can I do to disable the first-chance-exception called out of python code that's executed in a try...catch block?

Economize

Does the Python code contain try/catch? Presumably it doesn't, now it does get to be a judgement call where the "best" place for the debugger break should be located. Somewhat predictably, that won't be at a place where the Python code is no longer runnable and the actual source of the exception is no longer visible. You'd have to delete the PDB file for that C# code to convince the debugger that it is not "My Code". – Yancey

Do you see any? No it only contains Foo.Do(). I couldn't delete the PDB's because there's a lot of other code that should be debugged normally. – Economize

I didn't see any, you didn't post your Python code. Was there any point in being snarky about it? – Yancey

Please have a look at my posted C# code: engine.CreateScriptSourceFromString("Foo.Do()"); Here it is... There's no hidden code... – Economize

Answer 1

Most likely, you have a default option checked in your Debugging settings that's causing this:

Make sure that box is unchecked and you should be good to go. Hopefully that helps!

Cipher

Great idea. Haven't checked that before. ... This checkbox is unchecked but the debugger still stops :-( – Economize