Printing common elements between 2 collections

Not that I know of, though I've had interest in doing the same for TCL lists.

There's a script called "userListUtilities.tcl" in the gifts dir that might be useful. It contains a proc called "userIntersectLists" that takes 2 lists and finds the common elements. If you converted the collections to lists you could use it (or perhaps modify it for your use?).

For example - say I have a design with 2 instance: i0 and i1

encounter 2> set a [get_cells i*]
0x25 

encounter 8> set b [get_cells i1]                                        
0x27 

Collection a contains i0 and i1, and collection "b" contains just i1:

encounter 10> get_object_name $a
i0 i1

encounter 11> get_object_name $b
i1 

Then you could use this proc to interest them (which is probably what you've already written but perhaps a little more fast-running): 

proc userIntersectLists args {
  set res {}
  foreach element [lindex $args 0] {
    set found 1
    foreach list [lrange $args 1 end] {
      if {[lsearch -exact $list $element] < 0} {
       set found 0; break
      }
    }
  if {$found} {lappend res $element}
  }
  set res
} 

encounter 9> userIntersectLists [get_object_name $a] [get_object_name $b]
i1

We've discussed providing more list manipulation in the tool and this is a good example of where that would be helpful. We have pretty cool capabilities for shape manipulation with dbShape but basic TCL lists are, perhaps ironically, harder to work with at the moment.

Hope this helps,
Bob