Re: how to do bit-wise operation on none modular types?

[robert_dewar@my-dejanews.com]

In article <F81LB1.L19.0.-s@inmet.camb.inmet.com>,
  stt@houdini.camb.inmet.com (Tucker Taft) wrote:
> Samuel Mize (smize@imagin.net) wrote:
>
> Personally, I find "X mod 16#10000#" *more* clear than "X
> and 16#FFFF#" because bitwise "and" is working on the
> representation, whereas "mod" is working on the value,
> but vive la difference.

I could not begin to choose between these two without
knowing what the data in question represents. If it is
indeed logically an integer, then the first form is better,
but if in fact the integer is really a string of bits, then
the AND is clearer. Yes, you may say that the string of
bits would better be represented as a packed boolean array,
but if you are interfacing to some foreign environment
which thinks of it as an integer, it is actually safer to
map it into an integer. The trouble with the packed boolean
array is that you do NOT know the mapping of subscripts in
the array to bit positions in the integer.

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