in reply to Re^5: localizing lexical without messing with tie ?
in thread localizing lexical without messing with tie ?

> What do you call "passed variable"?

 
sub tst (&$) { 
   $_[1]++;   # passed variable
   $_[0]->(); # passed block
}
 
tst { print $c} $c;

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Cheers Rolf

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Re^7: localizing lexical without messing with tie ?
by ikegami (Patriarch) on Sep 10, 2010 at 01:50 UTC

    So "override a global lexical variable for a dynamic scope", where you have access to the global via an alias.

    Could you use $_, $a and $b or arguments instead?

    I don't see how PadWalker would help. If you found a solution using it, it might be possible to recreate the solution using B (a core module).

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      > Could you use $_, $a and $b or arguments instead?

      no, it's intended to allow an unlimited number of vars, and as a side note $a and $b could be tied too.

      As I said, forbidding tied vars is a good and pragmatic solution to get around this edge case.

      Cheers Rolf

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        it's intended to allow an unlimited number of vars

        Arguments do allow that. It seems that what you want is named arguments. Maybe you should use Sub::Parameters or something like that.

        You're striving for the awkward 

        my $c;
thing {
   ...
   ... $c ...
   ...
} $c;

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        but the following is clearer: 
        thing {
   my $c : Parameter;
   ...
   ... $c ...
   ...
};

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        and as a side note $a and $b could be tied too.

        So? I've already shown you how to completely localise a package variable.

        The advantage of $a, $b and $_ is that you don't need to declare them.

        As I said, forbidding tied vars is a good and pragmatic solution to get around this edge case.

        There are a lot more magic variables than just tied ones, but you're not likely to find them on lexicals without putting it on them explicitly.

        You'll also clobber dualvars and vars' pos().

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