in reply to A script can change itself
in thread can a script change itself?

The idea is great and it works nicely, but only if you are sure that you are the only user of this script. It will not work in a web-server environment or --heaven forbid-- in a mod_perl environment for instance where this same script could be called by more than one client at the same time as it has no protection against such classical race conditions.

I know "multiple concurrent user safety" wasn't part of the specs of this question, but I thought it would be good to give a word of warning here anyhow. I've been bitten before by race conditions when using cook-book (aka cut-and-paste) style programming before.

CountZero

"If you have four groups working on a compiler, you'll get a 4-pass compiler." - Conway's Law

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Re^2: A script can change itself
by Anonymous Monk on Mar 24, 2005 at 21:39 UTC
    I know "multiple concurrent user safety" wasn't part of the specs of this question, but I thought it would be good to give a word of warning here anyhow. I've been bitten before by race conditions when using cook-book (aka cut-and-paste) style programming before.

    I learned one lesson in my intro to concurrency course: "Concurrency is hard." There are few, if any, concurrent debuggers in existance ( one grad student was working on one, with some limited success), and the very convenient rule that states "if I run the same program, with the same inputs, I'll get the same output" goes out the window, because other programs can interfere.

    Avoid concurent programs when you can: when you can't, swear loudly and quadruple your delivery date.
    --
    Ytrew

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