Re: Types with physical dimension

["Paul Pukite" <pukite@daina.com>]

Paul Graham  <graham@clsi.COM> wrote:
>One can model physical types in Ada by using private types, but this
>involves writing a lot of operators.  What do Ada programmers do to guard
>against dimensional errors?

You don't necessarily need to invoke private types in Ada. By creating a 
derived type like:

   type Dollars is new INTEGER;  -- Also can put in range constraints

you cannot multiply two dollar objects in another package unless you
specifically state that you want the "*" operator used. (Ada 9X reduces 
the extra code required to "use" the "*".)

This guards against some of the dimensional errors as do the range 
constraints, but I agree that VHDL physical types are rather neat.

--
Paul Pukite (pukite@daina.com)       
DAINA Engineering 612/781-7600       
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