in reply to Re: Need Unused Variable Warning Msgs
in thread Need Unused Variable Warning Msgs

Writing a regex that parses Perl scopes is left as an exercise for the reader. Ultimately that's what tools like lint have done for C - they actually parse the C code just like a compiler would and do pattern matching to find bad code.

-sam

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Re: Need Unused Variable Warning Msgs
by Abigail-II (Bishop) on Jun 10, 2002 at 17:27 UTC
    Parsing C is orders of magnitude simpler than Perl. Not even perl can always pass Perl.

    But even if you have such a regex, to actually find out whether a variable is unused or not, you've got to know what a piece of code will do. To determine that at compile time, you need to solve the halting problem.

    If you solve the halting problem, I'll do the regex.

    Abigail

[reply]
      So how does lint do it? Does it solve the halting problem? I think it would be sufficient to determine if a variable as created in a scope with my() or our() and then never mentioned in the scope again. That would be useful enough to be worth the occaisonal false-positive that would result from evals and other nefarious tricks.

      -sam

[reply]
        lint doesn't need to solve the halting problem, as C doesn't have any switching between run-time and compile-time.

        Perl does.

        Abigail

[reply]

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