Luke,
On Oct 10, 2005, at 7:47 PM, Luke Palmer wrote:
How do you explain this:
class Foo {
method bar (Class $class:) { "class method" }
}
say Foo.bar; # class method
my $foo = Foo.new;
say $foo.bar; # class method
Assuming that that is valid Perl.
It is "valid" Perl 5, however (IMHO) it is *not* valid Perl 6.
To start with, the type of the invocant is Class, which $foo is not
derived from (it is an instance of something which itself is an
instance of Class).
I think that
$foo.class.bar()
should work. And changing the method defintion to be
method bar (Class|Foo $class:) { ... }
should work, but the code as you wrote it should not. Which means
that when we deal with Perl 5 classes within Perl 6, we should likely
give them an implied signature of (Class|Foo $self:) or some other
weirdness (I haven't thought that far down the line yet).
Class methods are strange creatures, in Perl 5 they were nothing
different than instance methods. In Java (static methods), they are
really just odd functions which need to be qualified by a class name.
Python doesn't even really have them (you have to jump through odd
hoops to make the method "callable"). Ruby uses Eigenclasses, and
CLOS uses something akin to eigenclasses. I am not sure how Smalltalk
handles things, but my guess is that class methods on Foo are
instance methods of classFoo, or some such.
They are ugly beasties no matter what, but eigenclasses (so far) seem
to be the prettiest of the uglies.
Stevan
