Vocabulary

[Luke Palmer]

So I'm seeing a lot of inconsistent OO-vocabulary around here, and it
makes things pretty hard to understand.

So here's how Perl 6 is using said inconsistent terms, AFAIK:

    - attribute
      A concrete data member of a class.  Used with C<has>.

    - property
      An out-of-band sticky note to be placed on a single object.
        Used with C<but>.

    - trait
      A compile time sticky note to be placed on a wide variety of things. 
        Used with C<is>.

    - role
      A collection of methods to be incorporated into a class sans
        inheritance (and maybe some other stuff, too).  Used with C<does>.

So for example:

    class Dog
        does Boolean                # role
        is extended                 # trait
        is Mammal                   # [1]
    {
        has $.tail;                 # attribute
        has @.legs;                 # attribute
    }

    my $fido = Dog.new
                but false;          # property

Hope that clears things up.

Luke

[1] This is a base class, which is an overloaded use of C<is>.  Though,
upon A12 release, we'll probably find out that it's not overloaded but
instead, elegantly unified, somehow.