Extract parameter as a dropdown list

Grasshopper
6

I’ve made a little component that automatically creates ValueList whenever it connects to an input with name-values:

namespace AutoValueList
{
    public class AutoValueListComponent : GH_Component
    {
        private bool _handled = false;
        private GH_Document _doc;
        public AutoValueListComponent()
          : base("AutoValueList", "AutoValueList",
              "Connect to an input with named value options to create a ValueList",
              "Params", "Input")
        {
        }
        protected override void RegisterInputParams(GH_Component.GH_InputParamManager pManager)
        {
        }
        protected override void RegisterOutputParams(GH_Component.GH_OutputParamManager pManager)
        {
            pManager.AddGenericParameter("ToNamedValue", "NV", "Connect to an input with named-values to create a ValueList",
                GH_ParamAccess.item);
        }
        protected override void SolveInstance(IGH_DataAccess DA)
        {
            _doc = OnPingDocument();
            if (_handled) return;
            _doc.SolutionStart += DocOnSolutionStart;
            _handled = true;
        }
        private void DocOnSolutionStart(object sender, GH_SolutionEventArgs e)
        {
            if(Params.Output[0].Recipients.Count > 0)
                AddRuntimeMessage(GH_RuntimeMessageLevel.Warning, "This input doesn't have named-values");
            var c = -1;
            for(var i = 0; i < Params.Output[0].Recipients.Count; i++)
            {
                if (!(Params.Output[0].Recipients[i] is Param_Integer)) continue;
                c = i;
                break;
            }
            if (c == -1) return;
            var recipient = Params.Output[0].Recipients[c];
            var paramInt = (Param_Integer) recipient;
            if (!paramInt.HasNamedValues) return;
            var namedValues = (IList)typeof(Param_Integer).GetField("m_namedValues", BindingFlags.NonPublic | BindingFlags.Instance)?.GetValue(paramInt);
            if (namedValues == null) return;
            var vl = new GH_ValueList();
            vl.ListItems.Clear();
            foreach (var nv in namedValues)
            {
                var name = (string)nv.GetType().GetField("Name", BindingFlags.Public | BindingFlags.Instance)?.GetValue(nv);
                var value = (int)nv.GetType().GetField("Value", BindingFlags.Public | BindingFlags.Instance)?.GetValue(nv);
                var vi = new GH_ValueListItem(name, value.ToString());
                vl.ListItems.Add(vi);
            }
            vl.NickName = recipient.NickName;

            var docIo = new GH_DocumentIO { Document = new GH_Document() };
            if (docIo.Document == null) return;
            docIo.Document.AddObject(vl, false, 1);
            vl.Attributes.Pivot = Attributes.Pivot;
            docIo.Document.SelectAll();
            docIo.Document.ExpireSolution();
            docIo.Document.MutateAllIds();
            var objs = docIo.Document.Objects;
            _doc.DeselectAll();
            _doc.UndoUtil.RecordAddObjectEvent("Create " + vl.NickName + " List", objs);
            _doc.MergeDocument(docIo.Document);
            recipient.AddSource(vl);
            _doc.DeselectAll();
            _doc.ScheduleSolution(1);
            _doc.SolutionStart -= DocOnSolutionStart;
            _doc.RemoveObject(this, true);
        }
        protected override System.Drawing.Bitmap Icon => Properties.Resources.List;
        public override Guid ComponentGuid => new Guid("875a0550-703d-43f3-819d-13f09315a05f");
    }
}

AutoValueList.gha (10 KB) (Grasshopper 0.9.76)
AutoValueList.zip (7.6 MB) (Source)

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