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From: edA-qa mort-ora-y (eda-qa_at_[hidden])
Date: 2004-07-04 12:42:52

Is there any interest in a library that performs strict type checking on
values with unit quantities? The intent is to prevent operation and
assigment of unlike types.

For example, if A is in meters/second, and B is in seconds:
        -A * B results in a value with "meters" units
        -A / B results in a value with "meters/seconds^2"
        -A = B results in an exception due to a mismatch

The code I have so far supports arbitrary unit types via tokens, which
have to be defined for a project. Some example code looks like (with
several notation options):

        typedef UnitValue<float> uFloat;

        UnitType unit_m( 1 ); //define meters type
        UnitType unit_s( 2 ); //define seconds type
        uFloat time( unit_s );
        time = unit_s( 3.0f ); //3 seconds

        uFloat speed( unit_m / unit_s );
        speed = 15 * speed.Type(); //set speed of 15m/s

        uFloat accel( unit_m / unit_s / unit_s );
        accel = speed / time; //results in 5m/s^2

        accel = speed; //throws exception, m/s != m/s^2
        time = accel; //throws exception, s != m/s^2

The library has a price for performance compared to native value
operations. However, part of the requirements will be a flag (a #define
) that turns off the unit processing for the code, which effectively
removes the classes (replaces the UnitValue simply with typedefs of the
stored type).

edA-qa mort-ora-y
Idea Architect

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