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Inheritance and instance-ship of astropy units unexpected #6517
Description
The base siunits are of class IrreducibleUnit, which does not inherit from Unit, which leads to some highly unexpected results.
>>> isinstance(u.m, u.Unit)
False
>>> isinstance(u.cm, u.Unit)
True
>>> isinstance(u.V, u.Unit)
True
>>> isinstance(u.A, u.Unit)
False
Activity
pllim commentedon Sep 6, 2017
A workaround for now is either to use
or
pllim commentedon Sep 6, 2017
Not sure if this is a bug or by design but the inheritance diagram here might also help:
http://astropy.readthedocs.io/en/latest/units/index.html#id2
mhvk commentedon Apr 13, 2018
Came across this while looking at older issues. The inheritance is confusing. As @pllim notes, the default would be to do
ininstance(unit, u.UnitBase)but this does not capture logarithmic units. I think we do need the abstract type discussed in #3650 -- indeed, I'll close this in favour of that issue (I copied the example on the top to it).