Recommended way to get registry of a quantity

[znicholls]

If I have an already initialised quantity, what is the recommended way to find out the registry that was used to make it? Should I just access ._REGISTRY even though it's technically part of the private API or is there a smarter way?

[znicholls]

Sort of a duplicate of #1071.

Further background: I ask the question for the case where I already have a quantity (but not the registry, so I can't use get_application_registry just in case the quantity came from a registry that differs from the application's registry) and I just want to create another quantity of the same registry. The simplest solution is to just access ._REGISTRY, but maybe I'm missing a better option.

[andrewgsavage]

you could use Quantity("1 m").__class__("1 mm") I don't think there's a public way to access the registry

[frankier]

Looking here https://github.com/search?q=pint+%2F%28%3F-i%29%5Cb_REGISTRY%2F+language%3APython&type=code&l=Python there are a lot of copies of pint itself but I definitely spot a few people using this "private" value. I also don't see why it's not exposed. It seems like it would be possible to write more general code this way rather than relying on get_application_registry which is effectively a global variable as far as I can see.