No longer being developed

The underlying RoslynPad library has been updated to support only .Net, not .Net Framework. I'm not planning to update this library to support .Net because it's used by .Net Framework projects.

The last update, V1.0.20, just updates the NuGet library (which was flagged as vulnerable), and adds a strong key to the assembly.

CDS.CSharpScripting

Super-simple .Net Framework tools for C# scripting, including:

1. C# code editor
2. Script compilation and execution

YouTube demo: https://youtu.be/YQy_tLJY_Mw

The code editor is a simplified wrapper around the amazing RoslynPad C# WPF code editor, via the RoslynPad.Roslyn.Windows NuGet pacakge.

Compilation and execution is built around Microsoft's open-source .Net compiler platform known as Roslyn, available from the Microsoft.CSharp package on NuGet.

Note there seem to be some bugs in Roslypad and/or AvalonEdit (the underlying text editor) that cause result in thread exceptions being thrown. See the notes below, ThreadException, on how to add a hook in your app to catch these.

Getting started

Use NuGet to bring in CDS.CSharpScripting to your project. This project is (currently) only written and tested around .Net Framework V4.8 WinForms development.

WinForms code editor

For the code editor, using a collection of commonly used namespaces:

1. Use the ToolBar to find the CodeEditor control and drag it onto your form.
2. In the Form's Load event handler initialise the editor by calling CDSInitialise.
3. That's it!

CDSInitialise has overloads that allow different namespaces and assembly references to be specified. See the demos for more information. It also allows the type of a global variables class to be specified - this allows for data sharing between the script and the host.

At any point the script can be read/written via the CDSScript property on the code editor.

To run the script:

1. Use EasyScript for simple compilation and execution.
2. Use the ScriptCompiler and ScriptRunning classes. These allow a compiled script to be run many times without needing to recompile. It also allows static data in the script to be retained between executions.

Capturing console output

A utility class, ConsoleOutputHook, allows any scripted Console.Write or Console.WriteLine output to be redirected programmatically. In the WinForms demo project we send this output to an OutputPanel.

using (var consoleHook = new ConsoleOutputHook(msg => outputPanel.CDSWrite(msg)))
{
    <snip/>
}

Walkthoughs

EasyScript

This requires the least infrastructure. Just call the Go method, pass in a script, and capture any returned data.

Example 1:

EasyScript<object>.Go("Console.WriteLine(\"Hello world, from the script!\");");

Output:

Hello world, from the script!

Example 2:

var easyScript = EasyScript<object>.Go("var x = y");
Console.WriteLine(easyScript.Summary);
foreach(var message in easyScript.CompilationOutput.Messages)
{
    Console.WriteLine($"Message: {message}");
}

Output:

Detected 0 warning(s), 2 error(s), runtime exception
Message: (1,10): error CS1002: ; expected
Message: (1,9): error CS0103: The name 'y' does not exist in the current context

Example 3:

var easyScript = EasyScript<string>.Go("return \"I am a message from the script!\";");
Console.WriteLine(easyScript.ScriptResults);

Output:

I am a message from the script!

ThreadException

At the time of writing, using RoslynPad 3.6.0, there are occasional WinForms thread exceptions - these are (probably) thrown when some activity is attempted on the wrong thread. For now, all we can do is send the exception to the debug output. Unfortunately this must be done from the host application to ensure it's applied before any UI controls are created.

In the WinForms test application, program.cs, we use this:

{
    HookThreadExceptions();
    <snip/>
}

private static void HookThreadExceptions()
{
    Application.SetUnhandledExceptionMode(UnhandledExceptionMode.CatchException, true);
    Application.ThreadException += Application_ThreadException;
}


private static void Application_ThreadException(object sender, System.Threading.ThreadExceptionEventArgs e)
{
    if (new[] { "RoslynPad", "AvalonEdit" }.Any(lib => e.Exception.StackTrace.Contains(lib)))
    {
        System.Diagnostics.Debug.WriteLine(
            $"Caught a WinForms thread exception, possibly due to a " +
            $"problem in RoslynPad or dependent library.");

        System.Diagnostics.Debug.WriteLine($"Exception message: {e.Exception.Message}");
        System.Diagnostics.Debug.WriteLine($"Exception stack trace: {e.Exception.StackTrace}");
    }
    else
    {
        System.Diagnostics.Debug.WriteLine($"Caught a WinForms thread exception, unknown reason.");
    }
}

Assembly memory leaks and re-using a script editor

It seems that programmatically loaded assemblies are not freed during normal garbage collection. This means that creating and disposing multiple instances of the editor progressively leaks memory. So far I can't find a way to fix this. I tried using an AppDomain (which can drop assemblies) but haven't managed to get it working in this UI environment.

For now, the best option I've found it to cache a script editor and effectively re-use it. The Reuse Editor demo shows how I've used a static instance of the editor, and keep it happy by moving it into a static 'parking' form each time the parent form is dropped.