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Re^2: Globs and globals

by Eyck (Priest)
on Jan 25, 2005 at 13:48 UTC ( #424861=note: print w/replies, xml ) Need Help??


in reply to Re: Globs and globals
in thread Globs and globals

This advice is factually incorrect.

GLOB is a glob, and local doesen't help here ( besides providing false sense of security )

my $socket=\*S1; print "Orig:",$socket,"\n"; { local(*S1, *S2); my $s=\*S1; print "Local: ",$s,"\n"; }
Orig:GLOB(0x8160be4)
Local: GLOB(0x8160be4)

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Re^3: Globs and globals
by BrentDax (Hermit) on Jan 25, 2005 at 18:40 UTC

    Odd--you're right, though I can't figure out why. The docs seem to say that you get a new glob when you localize:

    The construct local *name; creates a whole new symbol table entry for the glob "name" in the current package. That means that all variables in its glob slot ($name, @name, %name, &name, and the "name" filehandle) are dynamically reset.

    In any case, the following does work correctly:

    open(S1, "/dev/null"); $a=*S1{IO}; { local(*S1); open(S1, "/dev/null"); $b=*S1{IO}; } print "$a $b\n";
    IO::Handle=IO(0x101536f8) IO::Handle=IO(0x1013cdec)

    =cut
    --Brent Dax
    There is no sig.

      Interesting, your code works, although I would expect it not to. I haven't seen this excerpt in documentation about local and globs so it's a bit of surprise for me, thanks.

      There must be something about dual nature of globs - whatever experiment you devise it proves your theory, even if it contradicts other experiments.

        I think it may be that local *glob localizes the contents of *glob, not the glob itself. The docs could be read to support that.

        Or maybe it's just that the superposition-like nature of globs means that their behavior is governed by the Heisenburg Uncertainty Principle. Yeah, that's it...

        =cut
        --Brent Dax
        There is no sig.

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