Best practice to write highly user extendable C# application

Question

I am currently at a research institute that does micromaching/fine mechanics and was asked to develop a controller software for the current setup we use in one of our labs.

Answer 1

I did this 'script' thing using the .NET integrated C# compiler.
It is some work to do but basically is looks like this:

    public Assembly Compile(string[] source, string[] references) {
        CodeDomProvider provider = new CSharpCodeProvider();
        CompilerParameters cp = new CompilerParameters(references);
        cp.GenerateExecutable = false;
        cp.GenerateInMemory = true;
        cp.TreatWarningsAsErrors = false;

        try {
            CompilerResults res = provider.CompileAssemblyFromSource(cp, source);
            // ...
            return res.Errors.Count == 0 ? res.CompiledAssembly : null;
        }
        catch (Exception ex) {
            // ...
            return null;
        }
    }

    public object Execute(Assembly a, string className, string methodName) {
        Type t = a.GetType(className);
        if (t == null) throw new Exception("Type not found!");
        MethodInfo method = t.GetMethod(methodName, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);          // Get method
        if (method == null) throw new Exception("Method '" + methodName + "' not found!");                                  // Method not found

        object instance =  Activator.CreateInstance(t, this);
        object ret = method.Invoke(instance, null); 
        return ret;
    }

The real code does a lot more things, including a code editor.
It works very well for years now in our factory.

This way the users use C# for the scripts and can therefore use the same API as you do.

You can use a code template that looks like a plain .cs file. It is build at runtime and provided to the source parameter of Compile.

using System;
using System.IO;
using ...

namespace MyCompany.Stuff {
    public class ScriptClass {
        public object main() {

            // copy user code here
            // call your own methods here

        }

        // or copy user code here

        private int test(int x) { /* ... */ }
    }
}

Example:

string[] source = ??? // some code from TextBoxes, files or whatever, build with template file...
string[] references = new string[] { "A.dll", "B.dll" };

Assembly a = Compile(source, references);
object result = Execute(a, "MyCompany.Stuff.ScriptClass", "main");