[conradludgate]

This is mortifying. This should not be acceptable implicit behaviour for imports to implicitly run code by simply existing

[DonHopkins]

I know, right??! I was alternating between hitting my head up against the wall in despair, and jumping for joy I accidentally found a way to speed up detectron2 by 10%. I'll take the win.

YOLO: You Only Load Once

[buildbot]

That’s just the way Python works though, an import reads a script line by line defining the functions and executing calls. I think that’s true of any scripting language?

[DonHopkins]

How it works and how it should be used are different.

Say “no” to import side‐effects in Python:

https://news.ycombinator.com/item?id=7536246

https://chrismorgan.info/blog/say-no-to-import-side-effects-...

>I must be able to import your module— any module— at any time without anything breaking.

Or even the beneficial side effect of some other module running 10% faster. ;)

What side-effects, if any, are okay when importing a python module?

https://softwareengineering.stackexchange.com/questions/4540...

>Q: Is this a better design pattern or does it just kick the issue down the road?

>A: Kicking the issue down the road is the basic idea of the "functional core, imperative shell" design pattern.

Functional Core, Imperative Shell (2012):

https://news.ycombinator.com/item?id=34860164

https://www.destroyallsoftware.com/screencasts/catalog/funct...

[buildbot]

Well yeah, I wouldn't hold it that way either. The number of PRs I've commented on to take side effects out from imports is like , 75% of all the PRs I've seen in my current job.

Maybe Python 4 can make anything except a function definition or import be a syntax error in a module haha.

[zbentley]

C libraries compiled with -ffast-math would like a word…