in reply to Using "my" suppresses "Name used only once" warning?

At first I thought that perl would optimise away useless declarations, but after playing with B::Deparse I discovered that perl did not do this. And then I figured out why:

my $d;
my $s = '$d=10;print $d';
eval $s;

[download]

Naughty, but still legal. So in this case, it really is a feature, and not a bug.

____________________
Jeremy
I didn't believe in evil until I dated it.

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Re: Re: Using "my" suppresses "Name used only once" warning?
by PodMaster (Abbot) on Feb 03, 2003 at 08:25 UTC
    Good point.

    I vaguely recall of some discussion for addition of a compile time option to specify that you won't be using eval. The idea may seem appealing, but eval is eval, and s///e is eval, and there are tons of other uses for eval, and lots of modules use eval, that pretty quickly the potential optimization that might be gained by that option (at least for perl5) disappear pretty quickly (that's how I see it).

    MJD says you can't just make shit up and expect the computer to know what you mean, retardo!
    ** The Third rule of perl club is a statement of fact: pod is sexy.

[reply]
      s///e is eval
      No, that would be s///ee - the right side of s///e is compiled during the inital compilation phase.

      Makeshifts last the longest.

[reply]

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