Re: [OpenJade] Bugfix for +/- vs. length-specs

Subject: Re: [OpenJade] Bugfix for +/- vs. length-specs
From: Brandon Ibach <bibach@xxxxxxxxxxxxxx>
Date: Fri, 18 Jun 1999 02:03:31 -0500
Quoting Frank A. Christoph <christo@xxxxxxxxxxxxxxxxxx>:
> I'm not sure there is a bug here. 12.5.2 seems to say that + and - are only
> overloaded for length-specs when every argument is a length-spec. It looks
> to me like you are trying to elide that check. (I lost the original message
> but, as I recall, this started because someone complained because + didn't
> work as expected when applied to a length-spec and a non-length spec.)
> 
   On the contrary, the standard is quite clear.  The description of
the basic arithmetic operators from 12.5.2 is:

      These procedures behave in the same way as their counterparts on
      quantities, except that they shall return a length-spec if any <---
      of their arguments is a length-spec (as opposed to just a length).

   I think this makes perfect sense.  A length-spec is, by definition,
a length whose value is not yet determined.  So, a length-spec could
be "the height of this paragraph once it has been formatted", or it
could be "one half the height of...".  It's somewhat like the concept
of inexactness.  If any of the components of a calculation are inexact,
the result of the calculation will be inexact.

-Brandon :)


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