I am looking for a way to express something that resembles NPM's peerDependencies in setuptools.
My Python library is a plugin that should work with another Python library that I don't want to have as a dependency. Instead I'd like my end user to be responsible for it and install it by themselves. I can't find a proper way to express this in Python's setuptools (or any other build for that matter), to let my user "know" about the library
From my current understanding, this is a close approximation between the tools:
| NPM | setuptools |
|---|---|
dependencies |
install_requires |
optionalDependencies |
extras_require |
peerDependencies |
??? |
I have two possible solutions, both of which I find lacking:
Use extras_require anyway
Specify my requirements under an extras_require will do the job, but it feels like abusing it, because the user shouldn't install these extras.
Just document it
Inform the user that they need to install that package separately. Feels lame too
To my understanding, there is no need for that, as Python handles dependencies different anyway.
With npm/node you can have multiple versions of one package withing the same environment, if it required by one of the sub-dependencies (How does NPM handle version conflicts?)
This is not possible in Python. Only a single version of a library can be installed in the one environment. This means that the general issue that you are trying to solve with peer-dependencies, can not happen.
My recommendation is to specify your dependencies as normal, but with a loose version specifier.