[mardifoufs]

Try building a package and you will get hundreds of little paper cuts. Need a different index for some packages? It will work with a cli "pip install -from-index", but pip will not let you add an index in a requirement.txt for... security reasons. That means, good luck trying to "enforce" the CUDA version of pytorch without using third party tooling. So you either hard code a direct link (breaks platform portability), as that will work, or give up trying to make your project installable with "Pip install " Or "python build". Remember, pytorch basically has no CUDA builds anymore in its pypi index and no way to get CUDA torch from there (but I think this might have changed recently? )

Oh, and if some package you are using has a bug or something that requires you to vendor it in your repo, well then good luck because again, PEP 508 does not support installing another package from a relative link. You either need to put all the code inside the same package, vendored dependency included, and do some weird stuff to make sure that the module you wanted to vendor is used first, or... you just have to use the broken package, again for some sort of security reasons apparently.

Again, all of that might even work when using pip from the cli, but good luck trying to make a requirements.txt or define dependencies in a standard way that is even slightly outside of a certain workflow.

[vel0city]

You can include command line parameters like index-url and include-extra-index-url and find-links and what not in a requirements file.

[mardifoufs]

And have them build with "Pip install ." or python build? With the default setuptools config (or even any tweaks to it)? It works until you actually try to package the app, that's where the edge cases start piling up, a lot of them due to very weird decisions made on a whim on some random discourse thread.

Adding index URLs is explicitly not supported in the requirements.txt in setuptools or the default python build tool.