> "use vars" and "our" do roughly the same thing. They both
> let you use package variables under strict without fully-qualifying.
>
> All these code snippets pass strict, and they each set the
> package variable $foo ($A::foo, $B::foo, and $C::foo).
>
> use strict;
>
> {
> package A;
> use vars qw($foo);
> $foo = 'A::foo';
> }
>
> {
> package B;
> our $foo;
> $foo = 'B::foo';
> }
>
> {
> package C;
> $C::foo = 'C::foo'; # fully-qualifying
> }
>
> The main practical difference is, like you said, that "our"
> is new in 5.6. So if you want to support perl5.005_03 (which
> is still in relatively wide use) you have to "use vars" instead.
>
> But "use vars" and "our" work differently, and there are some
> subtle differences in their behavior.
>
> First of all, "use vars" does its magic by twiddling the
> symbol table, marking the $foo variable as "imported". Since
> the symbol table is global, you can use $foo any time you are
> in the package that imported it -- even if you're in a
> different block or file.
>
> package A;
> use strict;
>
> { use vars qw($foo) }
> $foo = 'A::foo'; # different block; no problem
>
> And for the same reason, a "use vars" declaration doesn't
> extend across two packages in the same block or file.
>
> package A;
> use strict;
>
> use vars qw($foo);
>
> package B;
> $foo = 'B::foo'; # different package: ERROR
>
> On the other hand, "our" does its magic by creating a lexical
> symbol (like a "my" variable) that is aliased to the package
> variable of the same name. Since lexical symbols are only
> visible in the scope (block, file, or eval) where they were
> declared, the "our" declaration doesn't exist outside this block.
>
> package A;
> use strict;
>
> { our $foo; }
> $foo = 'A::foo'; # different lexical scope: ERROR
>
> And when you have several packages in the same lexical scope,
> the "our" declaration extends across them.
>
> package A;
> use strict;
>
> our $foo; # alias to $A::foo
>
> package B;
> $foo = 'A::foo'; # STILL refers to $A::foo
>
> --
Thanks Steve,
Very imformative and helpful!
I'll read over hwta you and Rob said and let it soak in and go from there!
Thanks again,
Dan
> Steve
>
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