There is nothing exactly like wantarray in Perl 6. Functions can no longer
return different values based on context, because as Darren mentioned
above, it's a Bad Thing.
There are a few ways of doing something similar by returning mixins,
perhaps something like
return $num but [$num, $num2];
(which for some reason doesn't seem to work in rakudo right now)
But this is probably not a good idea, anyway. It would be better to
replace it with a clear interface for a new module, rather than reproducing
old context sensitive code. After all, Perl 6 is all about breaking Perl 5
idioms to fix them, why stop with the compiler?
On Thu, Mar 19, 2015 at 3:53 PM, Darren Duncan <dar...@darrenduncan.net>
wrote:
> I think as a general principle, multi methods should dispatch entirely on
> their parameter signatures, and dispatching on return type is just a bad
> design that leads to trouble. If you want different return types for
> identical parameters, you should give those 2 versions different method
> base names. -- Darren Duncan
>
>
> On 2015-03-19 3:20 PM, Tom Browder wrote:
>
>> I need to replace the Perl 5 'wantarray' and think a multi method with
>> differing return types should do it.
>>
>> So I've tried this:
>>
>> multi method foo($a, $b --> {Num,Num}) { #... }
>> multi method foo($a, $b --> Num) { #... }
>>
>> and get errors like:
>>
>> Missing block
>> at Ellipsoid.pm:672
>> ------> ethod to($lat1, $lon1, $lat2, $lon2 --> �{Rat, Rat})
>> from test_ellipsoid.pl:12
>>
>> I've tried parentheses, square brackets, and no grouping characters
>> instead of curly braces but that doesn't change the error.
>>
>> Question:
>>
>> How does one properly provide differing function return type signatures?
>>
>> Thanks.
>>
>> Best,
>>
>> -Tom
>>
>>
>
