Re: [PATCH lib/lib.pm 5.005_63] Removing use of vars.pm

[Michael G Schwern <schwern@pobox.com>]

On Sat, Jan 22, 2000 at 05:17:13AM -0700, Tom Christiansen wrote:
> >Also, our() might not be the right thing.  Sometimes, use vars is the right
> >thing, if you have multiple packages in a file and don't want to share.
> 
> use vars and our() both allow you to refer to a package variable
> without its package component.  But how is it that use vars somehow
> helps you in multiple packages?  That sounds like importing.

I believe he's refering to this possiblity:

package Foo;  
use vars qw($this);
$this = "Foo";

package Bar;
use vars qw($this);
$this = "Bar";

package main;
print $Foo::this;

That's fine.  But if you robotically replace "use vars" with "our":

package Foo;
our $this = "Foo";

package Bar;
our $this = "Bar";

package main;
print $Foo::this; 

You wind up with a lexical scoping problem:

"our" variable $this masks earlier declaration in same scope at -e line 1.
Name "Bar::this" used only once: possible typo at -e line 1.
Foo

I'll watch for this possibility and leave files with multiple package
definitions alone.

-- 

Michael G Schwern                                           schwern@pobox.com
                    http://www.pobox.com/~schwern
     /(?:(?:(1)[.-]?)?\(?(\d{3})\)?[.-]?)?(\d{3})[.-]?(\d{4})(x\d+)?/i

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Follow-Ups from:

Gurusamy Sarathy <gsar@ActiveState.com>

References to:

Tom Christiansen <tchrist@chthon.perl.com>

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