pip install should automatically perform pip check

[cbrnr]

I really like the new pip check feature. However, whenever I install/upgrade a new package, I need to manually perform this step to see if all requirements are still met. It would be really nice if pip could perform this check prior to installing/upgrading packages and issue a warning if there are broken requirements. Maybe the user could then be prompted whether or not to continue or abort the installation.

[pradyunsg]

It does. :)

It's limited to checking only the packages that require some of the installed packages. Essentially, it only checks the subset that's directly connected to the modified versions of packages.

[cbrnr]

Really? I have pyflakes 2.0.0 and flake8 installed. Then I wanted to update to pyflakes 2.1.0 using pip install -U pyflakes, which pip did but then pip check complained that flake8 requires pyflakes <2.1.0...

[pradyunsg]

Hmm... pip install -U, should have printed a warning.

Could you try that again and post the instructions for reproducing this?

[cbrnr]

You're right, I didn't notice the warning. I think there should be a prompt so that the user can't ignore the warning - it just installs anyway and I don't get a chance to abort.

[pradyunsg]

Yea, that's intentional.

There's no past precedent for pip install halting for input and in fact, doing it for just dependency issues, when really pip should do better dependency resolution isn't going to help anyone.

[cjerdonek]

FYI, there is precedent for pip asking for input during installs. It's not behavior I like, but it's there.

You can find some by searching the code base for ask_path_exists(). Here is one example during VCS editable installs:

pip/src/pip/_internal/vcs/__init__.py

Line 407 in e5f4bbb

response = ask_path_exists('What to do? %s' % prompt[0], prompt[1])

[cbrnr]

So are you saying that in my example pip shouldn't perform the update then?

[pradyunsg]

So are you saying that in my example pip shouldn't perform the update then?

It should, as per current behavior. It shouldn't though -- #988. (edit: clarified)

You'll want to check out #5000 and #5196.

[cbrnr]

OK, thanks for clarifying.

[lock]

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