>>>>> "TS" == Tolkin, Steve <[EMAIL PROTECTED]> writes:
TS> Rule of Representation: Fold knowledge into data, so program logic can TS> be stupid and robust. Even the simplest procedural logic is hard for TS> humans to verify, but quite complex data structures are fairly easy to TS> model and reason about. ... Data is more tractable than program logic. TS> It follows that where you see a choice between complexity in data TS> structures and complexity in code, choose the former. More: in evolving TS> a design, you should actively seek ways to shift complexity from code to TS> data. the problem is that you can't sweep complexity under the rug. overly complex data structures start to approach becoming languages themselves. and the code to support them starts to look more like interpreters. this typically happens when you need to make many logic flow decisions based on the data. it is like the space/time tradeoff in algorithms, you can gain in one at the expense of the other. rarely do you find a solution which gains in both. TS> Another related idea is this: "To reuse code you have to change the TS> data" (my paraphrase of a quote in TS> http://groups.google.com/group/comp.object/browse_frm/thread/2ebcb9c6cf8 TS> 6bf9f/318ede5cf4a01220?tvc=1&q=%22in+data%22+%22in+code%22+invariant+OR+ TS> invariants+OR+mellor&hl=en#318ede5cf4a01220 TS> The difference is that I am trying to find a quote that focuses on TS> the benefits of using data in a special way, as "control data", to TS> determine the specific execution path taken by the code. well you know my view, it is not a great quote and it can be easily reversed which doesn't help it much. i have seen complexity at all levels and you can't escape it totally. uri -- Uri Guttman ------ [EMAIL PROTECTED] -------- http://www.stemsystems.com --Perl Consulting, Stem Development, Systems Architecture, Design and Coding- Search or Offer Perl Jobs ---------------------------- http://jobs.perl.org _______________________________________________ Boston-pm mailing list [email protected] http://mail.pm.org/mailman/listinfo/boston-pm
