Is there a way to force Quantities to a specific unit per dimension on creation of the Quantity?

[matroscoe]

Pint is super useful but it is proving to be too slow in our application of the tool and I was hoping I could do some up-front work to avoid a lot of the time being spent inside the library.

My idea was to see if it is possible to set a unit for a dimension e.g. for length define that everything should be done in meters. Then whenever I create a Quantity with a dimensionality of "length" it would auto convert whatever dimensionality down to the base representation I want (e.g. Quantity(5, km) -> Quantity(5,000, m)).

This would allow me to avoid a lot of the conversion I see happening continually while still leveraging the ease of use the library provides. It also helps us move the more time consuming act of calculating all the conversions to when we load all the Quantity objects to the start of the application when users are more tolerant of slow operations (think loading screen in a video game). You tolerate it when you first start but every one you see past the initial one kind of pisses you off a little bit more each time you see it.

[matroscoe]

This is being discussed under #1750 I will add the related outcome back to this discussion when it is resolved but closing this now to stop any confusion between the two.