From: matz@... (Yukihiro Matsumoto)
Date: 2003-11-21T11:47:30+09:00
Subject: Re: "stereotyping" (was: Re: Strong Typing (Re: Managing metadata about attribute types) )

Hi,

In message "Re: "stereotyping" (was: Re: Strong Typing (Re: Managing metadata about attribute types) )"
    on 03/11/21, Chad Fowler <chad@chadfowler.com> writes:

|matz, how do you define "interface"?  In sean's case, class and/or module 
|were sufficient to define interface.  This is majorly what I take issue 
|with.  If "interface" is really a collection of "respond_to?" 
|requirements, then I can start to stomach the idea of it being added to 
|Ruby (I believe you were proposing something similar in your RubyConf 
|presentation).

I just don't know.  Only things I can tell you now are:

  * Types (or "interfaces" to avoid confusion) must be independent
    from class/module, otherwise they will be misused too often.  Note
    that Sean himself once failed to distinguish these two.

  * Thus I refuse at least part of his RCR, which use class/module to
    define interface.  Interfaces should be defined explicitly.

  * I'm sure I don't fully understand his new proposal in
    [ruby-talk:85888], but if it is statically checked at compile time
    as he explained, I wonder how much it is effective.  We have many
    cases where that kind of "static interface check" would not cover,
    thus make it "false promise".  I still need to examine his
    proposal to make the final decision.

  * The appearance matters.  I think the code example in the proposal
    does not look like Ruby:

      class Stdin
        def Boolean eof?
          return is-at-end-of-file
        end
        def Integer read(Integer maxbytes)
          return bytes-read
        end
      end

    I'm not sure how to design the interface syntax in the Ruby Way.

							matz.