Aaron Sherman wrote:
> > > $ref = [1,2];
> > > @ary[$ref] = foo(); # probably a syntax error
>
> Ok, as far as I can recall, Larry hinted that arrays and references to
> arrays would be interchangable in many contexts in P6. In this case, I
> can't see any reason that subscripting would *want* to do a SvIV on
> a known reference, so I would expect it to obey that logic and treat
> the reference as an array. Thus, I expect this to be list context for
> the exact same reason that:
>
> @bar = (1,2);
> @ary[@bar] = foo();
>
> would be.
The problem is *when* perl determines the context. If it's at compile-time,
then you can't say what $ref contains, so you can't conclude anything except
that it will be a scalar value (hence scalar context). Checking it at run-time
will give you the array/ref duality, but there's likely to be a *major*
performance hit if every use of a variable subscript has to be run-time
checked for context.
Hence, I suspect the rule will be something like: if it's identifiably an
array, list, or array ref at compile-time, it's a slice (and hence list
context); otherwise, it's a single element. After all, it's not such a
terrible burden to have to write the above as:
@ary[@$ref] = foo();
is it?
Of course, if one were to write:
my $ref is const = [1,2];
or:
my ARRAY $ref = [1,2];
then $ref *is* compile-time identifiable as an array ref, so you get a slice,
which confers list context.
That's kinda icky.
> Next question, though:
>
> $val = (foo())[0];
>
> List?
That would be my expectation. Just as in Perl 5.
Damian
