using handles or entity data to compare drawings

[Anonymous]

All, 

if someone could point me in the right direction on this:

1) i want to compare a newly received drawing (.dwg file-  mostly likely written to .dwg format from revit) to an old external reference that was created using an older version of that drawing using the command WBLOCK. Essentially im trying to automate the cleaning process of an external reference as we receive new backgrounds..

- From my understanding, handles can only be used to create references between drawings if they are the same drawing but older or newer version of the drawing. In my case: WBLOCK will create new handles for all entities being written into the new .dwg file. my own debugging has confirmed my theory that the handles are different.. However, I would like to hear it from someone with more experience before I move onto a different approach..

- If handles cannot be used in my scenario, can someone give me advice on how to approach this? My only thought is to iterate through the entities in the old external reference and compare them to the entities in the newly received drawings..This will get complicated as i will need to burst and explode blocks where required, but im up for hte challange just want to make sure im going about this the right way.

Thanks,

-John

[O_Eckmann]

Hi,

Why don't you use _COMPARE comand?

Olivier

[Anonymous]

Thanks for the reply olivier.. Unfortunately i dont think that will work as the _Compare or dwg compare built in to autoCad uses handles to compare drawings. In my scenario, if i use this - it will say both drawings are completely different because they are copies and not a version of the original drawing. 

I have had some success using a hashsets of layers, block reference names, and object types in the old external reference, then comparing those sets to the new incoming drawing and then WBLOCK ing those entities out to another drawing, but im curious if there is a better way to accomplish this.

Thanks,

-John