My main motivation is to divide the idea of the units library from a large "thing" that requires much effort at consensus, and developement into two smaller "things" - one dependant upon the other. In now way do I want to suggest that units is not important. Its just something that should be separate and sit on top of a dimensional analisys library. This view is motivated by my personal view that the effort involved in all apects of software development grows disproportionatly to the size of the project involved. If the project can be divided into layers, or losely coupled components, the effort is reduced significantly. Also, it results in a better, more elegant, more widely applicable design. So lets make a minimalist dimensional analysis library whose function is to check arithmetic operations at compile time for consistency. I'm not even convinced that fractional dimensions are needed. If the really are, maybe the library can take a template paramter the specifies either an integer or compile time rational type. This would cleave off another tricky piece - compile time rationals. This would diminish the load on the writer of the dimensional analysis library and leave the issue of fractional dimensions to someone who needs this sufficiently to create a compile time rationals package. Robert Ramey Andy Little wrote:
"Phil Richards" <news@derived-software.ltd.uk> wrote
On 2005-01-30, Andy Little <andy@servocomm.freeserve.co.uk> wrote:
It's all we need because *all* our interfaces to the outside world are defined entirely in terms of SI units.
1)Unfortunately not every one has the luxury. Many incoherent units exist in many real world situations, where errors cost money and worse. 2)Even within SI a quantity can be expressed in various units.
regards Andy Little