Setuptools, __init__ and __main__

[Ben Finney]

Rob Gaddi <rgaddi at technologyhighland.invalid> writes:

> So I'm trying to wrap my head around packaging issues

Congratulations on tackling this. You will likely find the Python
Packaging User Guide <URL:https://packaging.python.org/> helpful.

Also know that Python packaging was in a terrible state for a long
stretch of years, but now the Python Packaging Authority exists
<URL:https://www.pypa.io/> which has tended to steadily improve the
ecosystem in recent years.

> I'm developing applications of various size for internal deployment.
> When I'm actually getting the whole thing written, I've got my
> initialization stub in __main__.py, because it's an application rather
> than a library. But then when I migrated over to setuptools I had to
> switch it to __init__.py and change around all my import statements to
> compensate. Then I can reference it as an entry point.

Yes, it's one of the enduring bad parts of Python that it makes the
command-line invocation of an application overly awkward.

What do you mean by “initialization stub”? That could mean a lot of
different things, and I don't want to guess what you mean.

As for the difference between library versus application: You should be
writing all your code as discretely-testable units anyway, and unit
tests should be importing those in order to test them. So the whole lot
needs to be in a package hierarchy of some form in order to do that.

That said, I haven't made use of the “execute a directory as a program”
Python feature, so I might be misunderstanding what the problem is.

> This feels silly. I'm sure I could go stumbling around until I come up
> with an elegant solution, but does anyone already have one?

It seems to me the problem is avoidable by ensuring from the start that
all your code is importable by your unit tests; that way, it's ready for
a Setuptools entry point declaration without changes.

-- 
 \         “Quidquid latine dictum sit, altum viditur.”  (“Whatever is |
  `\                      said in Latin, sounds profound.”) —anonymous |
_o__)                                                                  |
Ben Finney