How does PIP determine the version of a dependency of multiple dependents

Question

Let\'s assume we have the following dependency tree in Python using PIP as package installer:

A==1.2.1:
|  - B==1.5.4
|  - C==?.?.?

D==1.3.0:
|  - C==?.?.?
         


        

Answer 1

On this topic, things will change relatively soon. Since pip's developers are currently working on a new dependency resolver:

• https://pyfound.blogspot.com/2020/03/new-pip-resolver-to-roll-out-this-year.html

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To test it today, you might want to install pip 20.2b1 and enable the unstable feature "resolver", with for example either one of the following:

• PIP_UNSTABLE_FEATURE=resolver python -m pip install SomeProject
• python -m pip --unstable-feature=resolver install SomeProject

See the following link for more details:

• https://discuss.python.org/t/announcement-pip-20-2b1-release/4242

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Other references:

• http://www.ei8fdb.org/thoughts/2020/05/test-pips-alpha-resolver-and-help-us-document-dependency-conflicts/
• https://pradyunsg.me/blog/2020/03/27/pip-resolver-testing/
• https://www.pythonpodcast.com/pip-resolver-dependency-management-episode-264/

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Update pip 20.2

• https://pythoninsider.blogspot.com/2020/07/upgrade-pip-20-2-changes-20-3.html