Michael Marcin wrote:
Matthias Schabel wrote:
Hi Michael,
When working in 3d simulations it is necessary to transform vectors to different spaces. Bugs sometimes crop up when, for instance, adding a object space vector to a world space vector or adding a vector from object a's object space to one from object b's object space. It would be nice to catch such inconsistencies at compile-time. I have a feeling a units-like library would be able to handle this but I have no idea how it would work. Here are two ways to do it, with the quantity wrapping the vector or the vector containing quantities:
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That's pretty cool and would likely catch many of the problems. The other error cases seem harder to detect at compile time. At least for my purposes there is only one world space but there can be an arbitrary number of object spaces. In addition it can be difficult to define correct conversions between spaces.
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If you think about it, you begin to realize that in *all* code involving arithmetic calculations (not just in physics or finance), you should wrap virtually every double with a type and define allowable operations using those types. This would catch a lot of errors at compile time.