Dynamic .NET

using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Geometry;
using Autodesk.AutoCAD.EditorInput;
using System.Collections.Generic;
using System.Linq;
namespace DynamicTyping
{
  public class Commands
  {
    [CommandMethod("CLN")]
    public static void ChangeLayerNames()
    {
      Database db = HostApplicationServices.WorkingDatabase;
      using (
        Transaction tr = db.TransactionManager.StartTransaction()
      )
      {
        LayerTable lt =
          (LayerTable)tr.GetObject(
            db.LayerTableId, OpenMode.ForRead
          );
        foreach (ObjectId ltrId in lt)
        {
          LayerTableRecord ltr =
            (LayerTableRecord)tr.GetObject(ltrId, OpenMode.ForRead);
          if (ltr.Name != "0")
          {
            ltr.UpgradeOpen();
            ltr.Name = "First Floor " + ltr.Name;
          }
        }
        tr.Commit();
      }
    }
    [CommandMethod("CLN2")]
    public static void ChangeLayerNamesDynamically()
    {
      dynamic layers =
        HostApplicationServices.WorkingDatabase.LayerTableId;
      foreach (dynamic l in layers)
        if (l.Name != "0")
          l.Name = "First Floor " + l.Name;
    }
    // Adds a custom dictionary in the extension dictionary of
    // selected objects. Uses dynamic capabilities, but not LINQ.
    [CommandMethod("AddMyDict")]
    public void AddMyDict()
    {
      Document doc = Application.DocumentManager.MdiActiveDocument;
      Database db = doc.Database;
      Editor ed = doc.Editor;
      PromptSelectionResult res = ed.GetSelection();
      if (res.Status != PromptStatus.OK)
        return;
      foreach (dynamic ent in res.Value.GetObjectIds())
      {
        dynamic dictId = ent.ExtensionDictionary;
        if (dictId == ObjectId.Null)
        {
          ent.CreateExtensionDictionary();
          dictId = ent.ExtensionDictionary();
        }
        if (!dictId.Contains("MyDict"))
          dictId.SetAt("MyDict", new DBDictionary());
      }
    }
    // Adds a custom dictionary in the extension dictionary of
    // selected objects, but this time using dynamic capabilities
    // with LINQ. Conceptually simpler, but with some performance
    // overhead, as we're using two queries: one to get entities
    // without extension dictionaries (and then add them) and the
    // other to get entities with extension dictionaries.
    [CommandMethod("AddMyDict2")]
    public void AddMyDict2()
    {
      PromptSelectionResult res =
        Application.DocumentManager.MdiActiveDocument.Editor.
          GetSelection();
      if (res.Status != PromptStatus.OK)
        return;
      // Query for ents in selset without ExtensionDictionaries
      var noExtDicts =
        from ent in res.Value.GetObjectIds().Cast()
          where ent.ExtensionDictionary == ObjectId.Null
          select ent;
      // Add extension dictionaries
      foreach (dynamic ent in noExtDicts)
        ent.CreateExtensionDictionary();
      // Now we've added the ext dicts, we add our dict to each
      var noMyDicts =
        from ent in res.Value.GetObjectIds().Cast()
          where !ent.ExtensionDictionary.Contains("MyDict")
          select ent.ExtensionDictionary;
      foreach (dynamic dict in noMyDicts)
        dict.SetAt("MyDict", new DBDictionary());
    }
    // Access various bits of information using LINQ
    [CommandMethod("IUL")]
    public void InfoUsingLINQ()
    {
      Document doc = Application.DocumentManager.MdiActiveDocument;
      Database db = doc.Database;
      Editor ed = doc.Editor;
      dynamic bt = db.BlockTableId;
      // Dynamic .NET loop iteration
      ed.WriteMessage("\n*** BlockTableRecords in this DWG ***");
      foreach (dynamic btr in bt)
        ed.WriteMessage("\n" + btr.Name);
      // LINQ query - returns startpoints of all lines
      ed.WriteMessage(
        "\n\n*** StartPoints of Lines in ModelSpace ***"
      );
      dynamic ms = SymbolUtilityServices.GetBlockModelSpaceId(db);
      var lineStartPoints =
        from ent in (IEnumerable)ms
          where ent.IsKindOf(typeof(Line))
          select ent.StartPoint;
      foreach (Point3d start in lineStartPoints)
        ed.WriteMessage("\n" + start.ToString());
      // LINQ query - all entities on layer '0'
      ed.WriteMessage("\n\n*** Entities on Layer 0 ***");
      var entsOnLayer0 =
        from ent in (IEnumerable)ms
          where ent.Layer == "0"
          select ent;
      foreach (dynamic e in entsOnLayer0)
        ed.WriteMessage(
          "\nHandle=" + e.Handle.ToString() + ", ObjectId=" +
          ((ObjectId)e).ToString() + ", Class=" + e.ToString()
        );
      ed.WriteMessage("\n\n");
      // Using LINQ with selection sets
      PromptSelectionResult res = ed.GetSelection();
      if (res.Status != PromptStatus.OK)
        return;
      // Select all entities in selection set that have an object
      // called "MyDict" in their extension dictionary
      var extDicts =
        from ent in res.Value.GetObjectIds().Cast()
          where ent.ExtensionDictionary != ObjectId.Null &&
            ent.ExtensionDictionary.Contains("MyDict")
          select ent.ExtensionDictionary.Item("MyDict");
      // Erase our dictionary
      foreach (dynamic myDict in extDicts)
        myDict.Erase();
    }
  }
}