I haven't seen a simple answer to this elsewhere, so documenting this here.  I know very little TCL but this works.

 

 

You need to declare the global variables BEFORE the function definition within the TCLCaller, then declare the variable as 'global' within the function.

 

 

eg.

 

-----------------------------------------------------------------------------------------

 

variable term

 

set term 1

 

 

proc MyFunction {} {

 

 

  global term

 

 

 

  FME_LogMessage fme_inform "term = $term"

 

  set term > expr $term + 1 ]

 

 

  # Set NEW attribute like this ..

 

  return $term

 

 

}