Allow installing an executable script pygridsynth

[jlapeyre]

For example, with
pip install .
or
pip install -e .

[HirokiHamaguchi]

@jlapeyre

Hello, I am Hiroki Hamaguchi, one of the maintainers of the pygridsynth project.
Thank you very much for your kind pull requests and issues — they help us a lot.

Regarding this PR, may I ask you a question?
I noticed that you added

from .__main__ import main

in init.py, but when I run python3 -m pygridsynth 1.00 0.01, it caused a warning saying:

<frozen runpy>:128: RuntimeWarning: 'pygridsynth.__main__' found in sys.modules after import of package 'pygridsynth', but prior to execution of 'pygridsynth.__main__'; this may result in unpredictable behaviour

I think this approach may not be the best, and I would like to improve it.
However, I am not entirely sure what feature you intended to add, which makes it difficult for me to proceed. Could you clarify your intention?

We plan to release a new PyPI version in a few days, so I would like to address this issue before the next deployment.

Thank you very much for your time and consideration.

[jlapeyre]

@HirokiHamaguchi

Thank you for pointing this out.
The current commit on main (404389b)

Allows

python -m pygridsynth ...

But the script now fails

pygridsynth ...

with

  File "/home/joeuser/github/quantum-programming/pygridsynth/.venvs/py313/bin/pygridsynth", line 3, in <module>
    from pygridsynth import main
ImportError: cannot import name 'main' from 'pygridsynth' (/home/joeuser/github/quantum-programming/pygridsynth/pygridsynth/__init__.py)

I have opened a PR #10 which allows both methods of running the program without errors or warnings.

[jlapeyre]

Ah.. And to clarify the intention. The desired feature is to be able to run pygridsynth like this:

pygridsynth ...

Rather than this

python -m pygridsynth ...

Hower, my first PR, which was merged, broke the second method. The new PR #10, should support both of them.

[HirokiHamaguchi]

Thank you very much for your prompt response and also for creating a new pull request. We truly appreciate your efforts.
I fully understand your intentions as well. After reviewing the pull request on our side, we plan to proceed with merging it.