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Postings from May 2008
On 2008-May-6, at 6:07 am, TSa wrote:
> Just to ensure that I get the our behavior right, consider
>
> sub foo
> {
> our $inner = 3;
> }
> sub bar
> {
> our $inner = 4; # redeclaration error?
> }
> say $inner;
>
> Does this print 3 even when foo was never called?
No, it throws an error about "$inner" not being declared properly --
just as in P5 you'd get 'Variable "$inner" is not imported. Global
symbol "$inner" requires explicit package name'.
There's no redeclaration error in bar() because it's declaring the
name for the first time (in bar's scope, that is), and then
(re)assigning a value to $inner, which is fine. If foo said "our Int
$inner" and then bar said "our Str $inner", that should be an error
though.
sub foo
{
our $inner = 3;
}
sub bar
{
our $inner = 4; # fine, assigns or re-assigns $inner
}
say $inner; # error, name "$inner" not recognised here
our $inner; # now the name is available in this scope
say $inner; # OK, $inner is undef
foo; say $inner; # prints 3
bar; say $inner; # prints 4
> IOW, is the assignment in foo a real one that only happens when foo
> is invoked or is it a pseudo-assignment that initializes the
> variables as if the whole statement where outside of foo?
The assignment happens only when foo() is invoked. However, the
variable $*Main::inner is declared at compile-time. Similarly, an
"our sub inner" inside foo() would declare the name, but you couldn't
call inner() until after running foo() --or bar()-- since you can't
call an undefined sub.
> The consequence of a sub not doing Package is that there are
> no separate foo::inner and bar::inner classes as in
>
> class foo
> {
> our class inner { has $.x = 3 }
> }
> class bar
> {
> our class inner { has $.x = 4 }
> }
> say inner.new.x; # error: no inner in scope
>
> My personal idea is to unify class and sub by allowing sub to do
> Package.
I don't understand what a "sub doing Package" is supposed to do. I
think you get the same thing from that last example whether foo and
bar are classes or whether they're subs: either way, bar will raise a
redefinition error, and "say inner.new.x" will throw a "no 'inner' in
scope" error.
-David
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