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use of ::?CLASS
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From:
John M. Dlugosz
Date:
April 17, 2008 23:22
Subject:
use of ::?CLASS
OK, what is the proper use of ::?CLASS ? Say in a role you want to take an argument of the same class as the final class, or explicitly declare $self. S12 gives an example:
method doit (::?CLASS $self: $a, $b, $c) { ... }
but this CONTRADICTS the idea that using the :: sigil in a declaration declares a generic type. And you can't spell ?CLASS without the sigil because you never have a twigil without a sigil and ?CLASS is not a legal identifier.
The example of
my @candidates := $object.WALK(:name<foo>, :breadth, :omit($?CLASS));
doesn't shed any light. The meaning of $?CLASS is never explained. Just a cryptic line in S02 "what class am I in (as variable)". Is the same Type object accessible as the value of the item with the $ sigil? Why is this necessary? I wonder if it has something to do with problems using the :: sigil that I'm musing with.
--John
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use of ::?CLASS
by John M. Dlugosz