Compound assignments? about units

[nholthaus]

I'm not sure it can be done. I could be wrong though, and if so would welcome a patch.

There is some nuance to working with arithmetic operators in the units library. Not sure how deeply you've delved into the code, but unit_t types are a CRTP construct inheriting from a so-called non-linear scale. The idea behind the NLS is that different arithmetic could be supported for different scales. So far, two are supported:

• linear scale: implements standard arithmetic
• decibel scale: implements log arithmetic for dB units

You could envision other logarithmic or exponential scales. I even did some testing that showed that datum-shifted scales like the Richter Scale were possible.

My recollection is a bit hazy, but I think when it came to compound assignment, I got foiled by the fact that base-class assignment isn't the same as inherited class assignment, or something like that. Or maybe it was just an oversight.

Additionally, you have to be careful with the enable_if template parameters (mostly not to break implicit conversion of dimensionless units back and forth to the underlying type), and the different RHS types that need to be supported. Copying an existing operator would be a good starting point. I'd encourage you to give it a try, at minimum you'll learn something, and then you could share that knowledge back with us :)

[nholthaus]

note to self: maybe possible as non-member?

[nholthaus]

I take back what I said, I think this is an easy addition.

[EvanBalster]

Cool, thanks! I had written my own implementation but I'll pull yours down now.

[nholthaus]

If you end up making any more improvements, feel free to share them back :)