Adding Namespace.__contains__()

[JaimieMurdock]

No issue for this, just a quick addition for usability/literacy while working with the library.

Proposed Changes

• Adds a Namespace.__contains__() method to enable syntax sugar of ref in ns. This is a natural way to discover if an arbitrary URIRef is in the Namespace.
• Current method would be manually writing ref.startswith(ns), which doesn't preserve semantics

This has possible extension to NamespaceManager, testing if a URIRef is in any managed namespace.

class NamespaceManager():
    def __contians__(self, ref):
        return any(ref.startswith(ns) for x, ns in self.namespaces())

Note that in NamespaceManager, namespaces are stored as URIRefs, not Namespace objects :/

Hoping this starts a discussion about some usability concerns.

[white-gecko]

Hey @JaimieMurdock, thank you for submitting a pull-request. I understand your motivation but I'm unsure if this extra code is worth the convenience as other.startswith(self) is a single expression as well. I understand the argument for the NamespaceManagemer, but as I see it would work without the proposed change but sure would make more sense if both classes get the __contains__() method.
So I'm 50/50 for this change, maybe @nicholascar or @ashleysommer have a stringer opinion ;-)

[JaimieMurdock]

I'll add the NamespaceManager.__contains__() method to a commit shortly.

The major motivator is "Readability counts." from PEP 20. Also, was the "natural" way of writing it for a relatively-new-to-Python student working on the project.

[JaimieMurdock]

Starting to peel back the layers on Namespace management and there's quite a bit of counter-intuitive typing - had to add a method to ClosedNamespace and _RDFNamespace as well. I'll write up a proper Issue today.

[JaimieMurdock]

Worth noting that #597 proposed the __contains__ functionality implemented here for 5.0.0.

[nicholascar]

I'm happy for any considered work to make any Pythonic ways of querying RDFlib objects work. I suspect that work to implement this function, even if the use of the output is essentially the same as the startwith way of working, will address inconsistencies or old coding styles in the code base so it is worth it.

So, if you're prepared to dive into Namespace to implement stuff and the PR passes all tests, great!

[ashleysommer]

I'll close this PR and re-open it to hopefully trigger Drone to see the PR and run its tests.

[ashleysommer]

Nope, looks like Drone only kicks in for new pull requests.
However the close/open did trigger the New travis config on travisci .com which does work a little bit better than the old one from travisci .org, see it here: https://travis-ci.com/github/RDFLib/rdflib/builds/216508899

[coveralls]

Coverage increased (+0.01%) to 75.492% when pulling ac51ae5 on JaimieMurdock:Namespace.contains into 8e3c771 on RDFLib:master.

[coveralls]

Coverage increased (+0.01%) to 75.492% when pulling ac51ae5 on JaimieMurdock:Namespace.contains into 8e3c771 on RDFLib:master.

[coveralls]

Coverage increased (+0.01%) to 75.492% when pulling ac51ae5 on JaimieMurdock:Namespace.contains into 8e3c771 on RDFLib:master.