Make the structure more similar to other languages

[martinsson]

Partly solves #63 by putting the app creation in a create_app() function that returns the created app

The connection is not closed as I don't know the best way to do this with the multi-processing api. I don't think that's necessary as I think it's closed by the multiprocessing terminate instruction though

WDYT @emilybache @codecop ?

[emilybache]

I don't like this at all, sorry. I don't like declaring the prices function inside the create_app function. I think it should be declared at the top level of a module. I also don't like naming the module 'main' since it is supposed to be the name of the flask app, it should at least be renamed to 'lift_pass' or similar. The database connection is created in a different thread from the request-response thread so it doesn't work at all with sqlite.

Having said all that I'm not all that experienced with Flask and I don't know the proper way to do this with Flask. It doesn't seem straightforward to create the app in one module and add routes to it in another.

[martinsson]

Indeed (although I did this on a project) it feels very non-python-like. In particular as python has the if __name__ == "__main__": which kind of handles this.

This allowed me to handle dependency injection in a hand-rolled manner. Here it allows both for injecting the connection and avoid the late initialisation.

I'm open for a better suggestion. But if we don't have a clear consensus of what to do I'd prefer to leave it as-is.

[codecop]

I am very strong in favour of having projects as similar as possible because it allows me to support multiple languages at once during one session. (I had issues several times whenever a single language was different.) I did regular diffs between languages in this repo in the past and do this also on other repos. So this change makes it look similar, see my original comment. On the other hand some variation is unavoidable due to language idioms or framework needs.

• I do not know enough Python to decide what is Pythonic-acceptable.
• Having the entry point with named similar across all languages is favourable because then the documentation is only needed once or not at all.
• I believe a module export is similar to a factory function - if that is the Python way because it allows such things.

[nicoespeon]

@martinsson unfortunately, that would not work because it returns a tuple:

If we go with this approach, I'd suggest extracting the app part like this:

Suggested change

	app = create_app()
	app, connection = create_app()

Thanks for the suggestion, it's interesting. I don't have a solid opinion to support this decision, but having experimented with this, I can say "it works". I would go for the most idiomatic approach in the language, but I don't have a lot of XP with Flask myself (it's been years) so I can't help here 😅

[nicoespeon]

We should also make it non-threaded, otherwise it doesn't work when we use the sqlite database:

Suggested change

	app.run(port=3005)
	app.run(port=3005, threaded=False)

That's because SQLite objects can't be used in different threads, but Flask is multi-threaded by default.