how typish are roles

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From:

TSa

Date:

October 25, 2006 00:20

Subject:

how typish are roles

Message ID:

453F1015.5060108@barco.com

HaloO,

from the recent threads 'class interface of roles',
'set operations for roles' and 'signature subtyping
and role merging' I wonder how typish roles actually
are. Some seem to consider roles as lightweight
particles that serve to compose classes. I see them
as the heavyweights in the type department. Doing a
role is like a contract about certain functionality.
So, what does @Larry think?

I know that S12 states "The type system of Perl
consists of roles, classes, and subtypes" but I don't
have a clear picture of the inner workings or the
formal model of this type system. E.g. what actually
constitutes a type? How are the classes related to
types? There is this fuzzy concept that a class is
also a role of the same name as far as typing is
concerned. How is the subtyping relation defined?


Regards, TSa.
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