lang/python is only needed if someone wants to run the examples out of the box. Should I turn this into an unconditional RUN_DEPENDS, or should I add a pkg-message, or ...?

I thought of a contrived case where it would be nice to have the option of not installing examples. We now support having multiple versions of python installed concurrently. In theory someone might want to install python2 and python3 versions of this port, though I don't know how pkg would feel about having two packages with the same origin. Other than examples, the two installations would not collide because, the package names have different prefixes, the main part of the port is installed under ${PREFIX}/lib/pythonX.Y/site-packages, and the license info is installed under ${PREFIX}/share/licenses/packagename. Only ${EXAMPLESDIR} would collide, which pkg would detect.

I was on the fence about PORTEXAMPLES=*

Mmmm, I missed this, in any case, the correct way to depend on python is:

EXAMPLES_USES=python:run

But I don't think it is necessary, it's python's only needed for examples, you should not add it to the dependency. You could add a pkg-message saying one will need python to use them.

Pkg doesn't care about origins any more, only PKGBASE, so, you could install both at the same time, but I'm not sure we support it.

Mmmm, there have been talks about adding PKGNAMEPREFIX/PKGNAMESUFFIX to EXAMPLESDIR/DOCSDIR, though it has not been through.

You could set:

EXAMPLESDIR=       ${PREFIX}/share/examples/${PKGNAMEPREFIX}${PORTNAME}

Belay that, you want to use:

USES=uniquefiles:dirs

Now that I think about it, one more time, this port already USES=python, so, while not depending on lang/python itself, it brings lang/python2 or lang/python3 depending on the default.

You should add something like this:

USES=shebangfix
python_CMD=${PYTHON_CMD}
SHEBANG_FILES= examples/*.py # or whatever works to get all the examples python files to be matched, note that it works in WRKSRC, not STAGEDIR

And maybe tweak python_OLD_CMD (default to /usr/bin/python) to match whatever shebang is present.

Because now that you support having both py27- and py34- versions of the port, with examples, installed, you need the examples to run the right python.