[Python-ideas] My objections to implicit package directories

[Paul Moore]

On 13 March 2012 06:07, Nick Coghlan <ncoghlan at gmail.com> wrote:
> However, so long as the backwards compatibility from PEP 402 is
> incorporated, and the new PEP proposed a specific addition to the
> tutorial to document the "never CD into a package, never double-click
> a file in a package to execute it, always use -m to execute modules
> from inside packages" guideline (and makes it clear that you may get
> strange and unpredictable behaviour if you ever break it), then I can
> learn to live with it.

Whoa! I'm not sure I can. I just recently got bitten badly by this for
real. The following was what I was doing:

1. I'm writing a package.
2. I'm trying to do the tests-as-I-develop approach (yes, I know I
should have been doing this for years - so sue me :-))
3. I have my tests as a subpackage of the main package.
3. I use the command line
4. I cd to the tests directory as that's the easiest way to edit
tests: gvim test_dow<TAB> to edit test_download_binaries.py.

And yes, I had endless trouble trying to work out why I can't then run
the tests from the command line. I consider the trouble I have as a
bug - it *should* work, in my view. I understand why what I'm doing is
an edge case, but intuitively, I don't like it not working.

I can change my practices, or use an IDE, or something. But my
workflow will be less comfortable for me, and I don't feel that I
understand why I should have to.

I *think* that what Nick is proposing is a fix for this (and if it
isn't, can you fix this scenario too, please Nick? :-)) and the idea
that it's going to get documented as "don't do that" strikes me as
unfriendly, if not outright wrong. I also don't think it should be
documented in the tutorial - it's not something a new developer hits,
it's later on, when people are writing bigger, more complex code, that
they hit it.

In summary, I guess I support Nick's objections 3 and 4. We need a
better response than just "don't do that", IMHO.

Paul.