Add __dir__ to DefinedNamespaceMeta.

[edmondchuc]

Fixes #1593

Proposed Changes

• Add __dir__ to rdflib.namespace.DefinedNamespaceMeta.

[aucampia]

Technically this breaks the interface, as anything that depended on the default dir implementation would break. Not sure if this is a serious concern, but something we should think about.

$ pipx run --spec rdflib==6.1.1 python3 -c 'from rdflib import RDF; print(dir(RDF))'
['_NS', '__annotations__', '__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', '_fail', '_underscore_num']

I highly doubt that this would be a problem for anyone though.

I'm fine with this approach and think it is likely best, but as a note to other reviewers; it would be good to think about other options, like providing an explicit method for it, thought that raises same concerns as before with name conflicts so that is likely worse.

[nicholascar]

I highly doubt that this would be a problem for anyone though.

Yes, I highly doubt this will be a problem too and I'm in favour of reporposing the well-known __dict__ for this, rather than adding a new method that people have to learn