"Malcolm McLean" <malcolm.mcle...@btinternet.com> wrote in message
news:1d6e115c-cada-46fc-9444-01e80e0af...@c10g2000yqh.googlegroups.com...
On Sep 27, 9:29 pm, p...@informatimago.com (Pascal J. Bourguignon)
wrote:
On the other hand, with the dynamic typing mindset, you might even wrap
your values (of whatever numerical type) in a symbolic expression
mentionning the unit and perhaps other meta data, so that when the other
module receives it, it may notice (dynamically) that two values are not
of the same unit, but if compatible, it could (dynamically) convert into
the expected unit. Mission saved!
I'd like to design a language like this. If you add a quantity in
inches to a quantity in centimetres you get a quantity in (say)
metres. If you multiply them together you get an area, if you divide
them you get a dimeionless scalar. If you divide a quantity in metres
by a quantity in seconds you get a velocity, if you try to subtract
them you get an error.
As you suggested in 'Varaibles with units' comp.programming Feb 16 2008?
[Yes with that spelling...]
I have a feeling that would quickly make programming impossible (if you
consider how many combinations of dimensions/units, and operators there
might be).
One approach I've used is to specify a dimension (ie. unit) only for
constant values, which are then immediately converted (at compile time) to a
standard unit:
a:=sin(60°) # becomes sin(1.047... radians)
d:=6 ins # becomes 152.4 mm
Here the standard units are radians, and mm. Every other calculation uses
implied units.
--
Bartc
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