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It was a combination of dissatisfaction with multiple inheritance (see Perl 5, C++), interfaces (see Java), and mixins (see Perl 5, Ruby), as well as an acknowl
by chromatic 14y ago
It was a combination of dissatisfaction with multiple inheritance (see Perl 5, C++), interfaces (see Java), and mixins (see Perl 5, Ruby), as well as an acknowledgement that aspects (see Java) and multimethods (see Common Lisp) solve part of the problem well and part of the problem poorly.
Then Allison and I saw Dr. Black present the Smalltalk traits paper and she realized that their formalism was exactly what I'd been talking about informally, so we borrowed that instead.
- tomp 14y agoHow are roles different from mixins? The only difference that I can think of is that mixins are declared at class declaration, is that what you mean?
- chromatic 14y agoRoles have specific composition rules which forbid name collisions; there's no last-in wins rule. Roles also provide type allomorphism which is much less ambiguous than duck typing.