folks, in attached progs, Im altering the optree that calls certain functions, and replaces the subroutine name with one thats munged to make it unique. When the program is run, the munged subs dont exist, and are handled by AUTOLOAD, which then can create a sub thats customized for each unique invocation. a2.pl works, a3 does not; it exposes problems either in my code or in the concept, Id like to understand which. Notes: (diffs between a2.pl and a3 ) perl -MO=Concise a3 shows much less data than with a2.pl, I think this is due the do {} block in a2.pl, vs a subroutine call in a3. Am I correct ? I recognize only 1 opcode chain ( with a few variations ), but am unable (as yet) to ascertain what other op-chains might invoke a sub. I could use some Hints as to how to create such opcode patterns, and out to see them with B::Concise. Code is rough (butt-ugly?), but after reading Nicholas Clark's posting, I figured its somewhat relevant. http://archive.develooper.com/perl5-porters@perl.org/msg90802.html