Obviously not an expert in xotcl, but this should be exactly the application for it in Tcl. Do you end up with a different command after this in xotcl, or can you still access the previous command?
the original command (the method being called) is not altered. xotcl interceptors allow to perform some action before the intercepted call and after the intercepted call. The interceptors can be dynamically added and removed, and they can be stacked.
