DPM Add-in Project Host Item Code File Names

     For DyanmicProgrammingModel (DPM) add-in projects, the file name of the host item code file generally matches the name of the host item.  For example:  in the SDK sample ShapeAppDynamicProgrammingModelCSharp the host item “Drawing1” would have a corresponding code file named either “Drawing1.cs” or “Drawing1.vb”.  However, there is an exception to this rule.  If a host item has been removed, then a new one added with the same name as the host item which has been removed, the DPM code file associated with the newly added host item will be named “HostItem#.xx”.  For example:  in the SDK sample if “Drawing3” was removed the corresponding code file “Drawing3.vb” would be removed from the DPM add-in project.  Then, if a new drawing was added it would be named “Drawing3”; however, the corresponding code file would be “Drawing31.vb”.

     This is due to a file which lingers once a host item has been removed.  Of the three host item code files associated with each host item, namely HostItem.xx, HostItem.Designer.xml, and HostItem.Designer.xx, only the designer files are actually deleted when a host item is removed.  The main, or visible, code file HostItem.xx is not deleted when the host item is.  This residual file is removed from the DPM project; however, because the file still exists the new host item’s code file name is automatically appended with a number to avoid a naming collision.

Note:  It is possible to use any valid name for the code file of a host item; this is specified in the first parameter “name” of the AddProjectHostItem methods.

//From DesgignTimeIntegration.AddProjectHostItemInternal
projectHostItem = 
  hostAdapter.ProjectHostItems.AddProjectHostItem(
  itemName, //<== specify the host item code file name here
  "Microsoft.VisualStudio.Tools.Applications.Samples.ShapeApp." + itemEntryPoint,
  "Microsoft.VisualStudio.Tools.Applications.Runtime.IEntryPoint",
  itemName,  //cookie name
  this.hostItemTemplatesPath + @"\" + languageFolder + @"\" + templateName);

     For more information on the DyanmicProgrammingModel and the associated SDK sample please see the MSDN documentation Dynamically Creating and Modifying Host Items and Host Objects in an Add-in Project