Args.cs

using System;
using System.Collections;
using System.Reactive.Linq;
using Pythonnet = Python.Runtime;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Reflection;

namespace Bonsai.Scripting.Python
{
    /// <summary>
    /// Represents an operator that takes a sequence of python objects and converts them to a type of PyTuple to pass as arguments to a function.
    /// </summary>
    [Combinator]
    [WorkflowElementCategory(ElementCategory.Transform)]
    public class Args
    {
        public IObservable<Pythonnet.PyTuple> Process(IObservable<object> source)
        {
            return source.Select(obj =>
            {
                using (Pythonnet.Py.GIL())
                {
                    if (!(obj is ITuple || obj is IList || obj is Array))
                    {
                        if (obj is Pythonnet.PyObject pyObj)
                        {
                            return new Pythonnet.PyTuple(new Pythonnet.PyObject[] {pyObj});
                        }
                        
                        return new Pythonnet.PyTuple(new Pythonnet.PyObject[] {Pythonnet.PyObject.FromManagedObject(obj)});
                    }

                    PropertyInfo[] properties = obj.GetType().GetProperties();
                    Pythonnet.PyObject[] pyObjects = new Pythonnet.PyObject[properties.Length];

                    for (int i = 0; i < properties.Length; i++)
                    {
                        object value = properties[i].GetValue(obj, null);

                        if (!(value is Pythonnet.PyObject))
                        {
                            throw new ArgumentException($"All elements of the tuple must be of type PyObject. Instead, found {value.GetType()} for Item{i+1}.");
                        }

                        pyObjects[i] = (Pythonnet.PyObject)value;
                    }
                    return new Pythonnet.PyTuple(pyObjects);
                }
            });
        }
    }
}