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Re: [eiffel-nice-library] STRING.put and infix "+", CHARACTER.out

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  • James McKim
    It s a pity cause we end up with four clauses instead of just one, but I don t see an alternative given there s no agreement on what CHARACTER.out should be.
    Message 1 of 2 , May 1, 2000
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      It's a pity 'cause we end up with four clauses instead of just one,
      but I don't see an alternative given there's no agreement on what
      CHARACTER.out should be.

      -- Jim McKim


      Roger Browne wrote:

      >
      > Doug Pardee wrote:
      >
      > > I'm thinking that it might be time to back away from the proposed
      > > postcondition on STRING.put
      >
      > [Here is the "proposed postcondition" referred to by Doug:]
      >
      > ensure
      > replaced: is_equal (old substring (1, i - 1)
      > + c.out + old substring (i, count))
      >
      > > ... we're tying the postcondition to non-basic specifiers not only of
      > > its own class, but of class CHARACTER as well. In essence, we're
      > > requiring that both STRING.infix"+" and CHARACTER.out be defined AND
      > > IMPLEMENTED in such a manner that the postcondition on STRING.put is
      > > valid.
      >
      > ..and we already know that CHARACTER 'out' is not currently
      > interoperable...
      >
      > > That doesn't give me a warm feeling inside...
      > > I greatly prefer the postconditions that Roger originally proposed as
      > > an alternative...
      >
      > [Here is the "alternative" version, also preferred by Joachim:]
      >
      > ensure
      > stable_count: count = old count
      > replaced: item (i) = c
      > stable_before_i:
      > substring (1, i - 1).is_equal
      > (old substring (1, i - 1))
      > stable_after_i:
      > substring (i + 1, count).is_equal
      > (old substring (i + 1, count))
      >
      > I think Doug makes a strong point. We are trying to foster
      > interoperability, and we are trying to produce a rigorous specification.
      > Both of those goals are better served by the "alternative" version.
      >
      > I intend to use the "alternative" version for the upcoming vote on
      > STRING 'put'.
      >
      > However, if three or more people request it I will also put the
      > original, shorter postcondition in the vote as an A-B choice.
      >
      > Regards,
      > Roger
      > --
      > Roger Browne - roger@... - Everything Eiffel
      > 19 Eden Park Lancaster LA1 4SJ UK - Phone +44 1524 32428
      >
      > ------------------------------------------------------------------------
      > Accurate impartial advice on everything from laptops to table saws.
      > http://click.egroups.com/1/3020/0/_/1718/_/957106577/
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      >
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