Mark J. Reed wrote:
Jonathan Lang wrote:
> Good examples. Now could you provide some to explain to me why it's
> important to distinguish between '$', '@', '%', and '&'? I ask
> because I've seen a lot of object-based code that has said stuff like
> '$container{$key}';
Well, $container{$key} is how you access elements of %container in
Perl5; in Perl6 that's %container{$key}. But in object-based P5 code,
you'd be much more likely to see $container->{$key}, where $container
contains a reference to a hash.
True; but not at all what I was referring to.
I believe in P6 you could write that
either as $container.{$key}, $container{$key} (where the . is implied
since $container{$key} can't refer to %container anymore), or
%$container{$key}.
_This_ is closer to what I'm referring to. As I understand it, Hash
is a role that provides (among other things) postcircumfix:<{ }>. So
any object that does Hash should be able to call the above method.
And unless I've missed something, there's nothing in perl 6 that
insists that an object that does Hash must be assigned to a variable
that uses the '%' sigil; the '$' sigil seems to work equally well.
i.e., I've seen code to the effect of:
class Foo does Hash { ... }
my $obj is Foo;
$obj<key> = 5;
say $obj<key>;
In short, it appears that there's nothing keeping you from assigning
hash-like or list-like objects to scalar variables.
And this is without bringing references into the picture.
You aren't the only person who feels this way; there was a proposal
back in the RFC process to remove sigils in favor of "everything is a
scalar, dereference as needed". I was in that camp myself. But Larry
rejected that proposal, defending the utility of sigils, and I have
been swayed by the arguments, which I'm not going to repeat because I
can't say it as well, but I do advise you to go read - it was either
Apoc1 or Apoc2, I think.
I have never been in that camp. In fact, I tend to see the points I
raise above as a bug, not a feature.
Perhaps the relationship between sigils and roles will be addressed in
the as-yet unwritten S14 (or whichever spec is supposed to address
tied variables)?
--
Jonathan "Dataweaver" Lang
