PERL lets you see what it looks like while it is running. By observing a periodic dump of the syntax tree, one can see if a PERL program has changed functionally, including all of its inherited code (We concede that mucking with PERL primitives (SVs etc) themselves means functionality would change with identical trees). Assuming a safe PERL binary, this would suggest that a program that dumps and checks an MD5s of its syntax tree somehow would be pretty hard to change, even in-memory. Does anyone know more about this kind of thing? We have a working example of this and are naively trying to propose a solution to the "what code is that server really running" problem.
Craig.