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Re: Re: Caller's Variables

by broquaint (Abbot)
on Jul 08, 2002 at 13:30 UTC ( [id://180175]=note: print w/replies, xml ) Need Help??


in reply to Re: Caller's Variables
in thread Caller's Variables

That is, lexical variables that don't share a scope are unreachable.
Not strictly true since you can modify lexical variables with the help of PadWalker. Here's some code from the docs
sub increment_my_x { my $h = peek_my (1); ${$h->{'$x'}}++; } my $x=5; increment_my_x; print $x; # prints 6
Although you'd have to be quite a disturbed individual to use this sort of thing in production any code ;-)
HTH

_________
broquaint

Replies are listed 'Best First'.
Re: Re: Re: Caller's Variables
by shotgunefx (Parson) on Jul 08, 2002 at 20:21 UTC
    I could see one or two valid uses. The one place I've used it for production was a tied hash package. We wanted to be able to alias package vars in the hash values with vars from the caller. Retrofitting this to older code was a pain as they HAD to be package variables so we changed the alias sub to look at caller's lexicals and then the package vars.

    -Lee

    "To be civilized is to deny one's nature."
    Update
    While on the subject, I should mention a bug/feature of PadWalker. It will NOT see all lexicals visable where the subroutine is called if you have a bare block
    #!/usr/bin/perl -w use strict; use PadWalker qw(peek_my); my ($oa,$ob) = ("Outer One", "Outer Two"); { my $inb = "Bare Block"; # Will not be seen by peek_my peeper(); } sub peeper { my $c = peek_my(1); print "Lexicals:\n", (map { "Found $_ with value $c->{$_}\n" } sor +t keys %$c ),"\n"; }


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