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Programmer-defined data types
Date: Mon, 21 Aug 89 11:34 PDT
Date: Fri, 18 Aug 89 18:36:26 PDT
Returns a procedure for constructing new members of the type represented by
rtd. The returned procedure accepts exactly as many arguments as there
were slot-names in the call to MAKE-RECORD-TYPE that created the type
represented by rtd; these are used, in order, as the initial values of
those slots in a new record, which is returned by the constructor
I prefer the alternative that someone (RRJ?) made the last time we
(RECORD-CONSTRUCTOR rtd slot-names)
Where slot-names is a subset of the slot-names given to MAKE-RECORD-TYPE.
The returned procedure accepts exactly as many arguments as there are
slot-names. It creates a new record and initializes the specified slots.
I agree with this wholeheartedly. I think this form of the
constructor-constructor is significantly more useful.
-- A case can be made that constructor procedures should take no arguments
and leave all slots in new records uninitialized. There appear to be
advantages to both points of view.
I'm not sure I understand why anyone would advocate this. Would such
people be made happy if
(RECORD-CONSTRUCTOR SPACESHIP-RTD '())
returns such a constructor? Or do such people think that the user should
be forced to use side-effects to initialize records?
If it is the case that there are advantages to both points of view,
then whatever is provided should support both. I think Alan's
suggestion does this.