Auto-freeze new xref'd layers on open?

We have two departments who share data between them via xrefs. I xref their
drawing and freeze the data I don't need and visa versa. However, when a
new layer is created in an xref it shows up unwanted in the host drawing.
Yes, it's the nature of the beast but there is no simple solution (freezing
the newly created layer in the xref is not an option for us and neither is
duplicating the data and keeping track of changes between depts).

So, I was thinking of an app to freeze new xref layers upon. I figure that
I'll have to store the present list of xref layers (separate lists for each
xref) and fire off the app only if the lists are found. How to store the
list? Dictionary perhaps? I'm also worried about any possible processing
overhead as well as problems I haven't thought of yet.

I would appreciate any ideas or concepts as to a reasonable and efficient
approach to this little but annoying problem.

Thanks,
Josh

 

Xrefs are resolved before any custom code fires, therefore, if you are
certain to unload the Xrefs before you close the drawing, (maybe interrupt
the close operation to automatically unload xrefs), then you can run some
code after a drawing is opened but before the Xrefs are loaded

the code will note what xref layers exist, load the xrefs, then notice any
new xref layers! this way, you wont need to store the list of layers
separately from autocad. i cannot think of an easy way to run code before
xrefs are resolved unless they had been previously unloaded. a drawback is
not be able to distinguish xrefs that you want to remain unloaded! (that
would require storing a separate list of xrefs (maybe thats easier than
storing a list of layers))

good luck