Code block to get filepath of shapefile in field calculator

Discussion created by wwaters on Mar 9, 2011
Latest reply on Sep 16, 2015 by FGibson-esristaff
Does anyone know a python codeblock to input the filepath of a shapefile in a field using field calculator?

I'll be merging a whole lot of shapefiles later and it would be good to keep track of each record in manner.