Re: Definable operators

Herman Rubin <hrubin@stat.purdue.edu> wrote:
>The claim that shifting is "not that common" is questionable. I have
>used it much more for other purposes than I have done other than
>simple formatted I/O, for which it is not needed.


I agree here, though shifting is strange in two senses. Most programs
don't need it at all but, those that do, tend to use it very heavily.
More seriously, the bit manipulation operations are typically the
subset used by a certain class of mathematicians, rather than
programmers. For example, one of the most common requirements is for
the basic operation "is every bit in A also set in B?" which has to be
coded very messily in most languages.


>This is one of the problems of language designers and compiler
>writers, and even for hardware designers. It is often quite easy to
>put something in at design time, and quite difficult to find a
>work-around later. It is quite easy to destroy common notation for
>computer purposes, and hard to get it back.


And conversely. Getting rid of misguided facilities is even harder.


Nick Maclaren,
University of Cambridge Computer Laboratory,
New Museums Site, Pembroke Street, Cambridge CB2 3QG, England.
Email: nmm1@cam.ac.uk
Tel.: +44 1223 334761 Fax: +44 1223 334679
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