RE: Dimensionality Checking (Ada 20XX)

["Robert C. Leif, Ph.D." <rleif@rleif.com>]

From: Bob Leif
To: Nick Roberts et al.
"you can convert from one fixed point type to another, if their deltas and
ranges are appropriately set, but these must be static."

This is both true and unfortunate. I can understand that because of
backwards compatibility and perhaps safety issues and compiler issues why
the default for the compiler must remain static. However, I believe that a
trap-door should be created, at least for type decimal, to permit the deltas
and digits to be changed at run-time with the obvious proviso that they stay
within the capabilities of the compiler. They could be specified as part of
a generic.

In the pre-calculator period, when I started in science, we used
slide-rules. The exponent was calculated by summing the numerators and
subtracting the sum of the denominators. It would be useful if a 1 Gigahertz
computer had the capabilities of a simple, analog device that consisted of
two pieces of wood and a transparent plastic slider. One other approach is
to support a decimal floating point type.

-----Original Message-----
From: comp.lang.ada-admin@ada.eu.org
[mailto:comp.lang.ada-admin@ada.eu.org]On Behalf Of Nick Roberts
Sent: Thursday, December 13, 2001 2:23 PM
To: comp.lang.ada@ada.eu.org
Subject: Re: Dimensionality Checking (Ada 20XX)


> Hah! That's a comment that O will touch upon further down.

I meant: That's a comment that I will touch upon further down.

And I never really did. My point simply is that you can indeed dynamically
convert between feet, meters, inches, angstroms, parsecs, etc. within a
single floating point type (usually) with impunity. You can't generally do
this within one fixed point type; you can convert from one fixed point type
to another, if their deltas and ranges are appropriately set, but these must
be static.

--
Nick