Dear Terry,
Thank you for your query.
I am sorry to say that the answer to your first and main question is simply no.
Generally, a Revit add-in requires recompiling for a new major release of Revit.
Say you have implemented and installed your add-in for and on Revit A, and the user updates to a new major release Revit B.
Due to the fact that the .NET framework isolates the add-in from the underlying API to a certain extent, all the functionality in the Revit B API that remains unchanged from Revit A will continue working.
However, unlike AutoCAD, Revit does not maintain backwards API compatibility.
For instance, access to the endpoints of a curve element used to be via the indexed EndPoint property, taking an argument 0 for the start and 1 for the end endpoint.
In C#, this property was automatically translated to a method get_EndPoint, whereas in Visual Basic, it remained unchanged, an indexed property EndPpint.
In Revit 2014, this property was declared deprecated and replaced by a new method GetEndPoint which is and remains a method under all circumstances and in all languages.
In the next major release of Revit, the deprecated method will be declared obsolete and removed.
From that moment onward, a Revit 2012 add-in trying to access the EndPoint property (or get_EndPoint method in C#) will cease working.
So Revit provides much less backwards API compatibility than AutoCAD.
Users are encouraged to update in a more timely fashion.
One important tip for AuoCAD developers is to try to let go of the expectations that working with Auto CAD APIs has fostered ... Revit is a different animal and the experience and expectations coming from any other CAD system can be just as much a hindrance as an asset:
http://thebuildingcoder.typepad.com/blog/2012/02/bim-versus-free-geometry-and-product-training.html
http://thebuildingcoder.typepad.com/blog/2012/10/porting-an-autocad-application.html
On the other hand, the Revit API is much smaller and simpler than AutoCAD's. An experienced programmer should be able to get going within a few hours, and understand everything there is to know within a few days, which is definitely not possible in AutoCAD.
One last thing: in Revit add-in development, it is more important than in AutoCAD to have a good product and user workflow understanding before beginning to think about any application development, both because the workflows in real BIM projects are more complex, and because the API more closely mimics and supports the user interface functionality. As always, it is important to go with the flow, and not fight against it.
I hope this helps.
Good luck getting into the Revit API.
Best regards,
Jeremy
DotSoft: The Leading Developer
