On Mon Sep 25, 2006 at 10:09:45 +1000, Mark Greenaway wrote: >Although I came to the thread a little late, I was interested to see >that an issue close to my heart came up, which is operator overloading >with respect to numeric types. The specific example of date types was >raised. > >As someone who has both programmed professionally for many years and >just recently begun a science degree majoring in mathematics, I've >become interested in how to do certain calculations within programming >languages, and how those programming languages could be improved to make >writing numeric code less error prone. > >At the moment, I spend some of my time calculating unit conversions: >degrees to radians, electrovolts to joules, angstroms to metres, >concentration of H+ to ph etc. etc. It's fun the first time, a little >less so the second time and downright tedious from then on. I'm sure >similiar problems come up in other fields over and over again. For >instance, some people working in financial institutions define a >currency type that includes not only a quantity but also the currency, >be it francs, dollars, pounds or whatever. > >I was wondering if anyone was aware of a standard approach >developing numeric types that include their units, or other information >relevant to them. For instance, if you had a weight in grams and another >weight in kilograms, and you attempted to do arithmetic on them, it >would make the appropriate unit conversions for you. If you were >attempting to do a calculation that makes no sense, such as adding >weight to time, it could signal an error (preferably at compile time). >Of course, multiplying and dividing by different types of units is fine. >This sort of unit checking could catch a whole class of errors that are >often made in routine calculations. > >I'm sure I'm not the first person to have thought of this. Has anyone >seen or used data types that use these sorts of ideas?
I've come up with something in python do do this along the lines of: >>> kg(1) + grams(1000) 2kg >>> m(100) / seconds(1) 100 ms-1 >>> If anyone cares I'll try and find the code and post it. Benno _______________________________________________ coders mailing list coders@slug.org.au http://lists.slug.org.au/listinfo/coders
