pip install --fail-on-missing-deps

[anntzer]

I'd like to suggest a flag that would prevent installation of any dependencies (like --no-deps) and fail if any dependency is missing (printing out the list of missing dependencies).

Use case: environments when most packages should be installed via another package manager, e.g. conda or $linuxdistro-packagemanager and some package is not available for that package manager, but I'd still like to install whichever dependencies I can using it.

[xavfernandez]

A solution could be the use of --no-deps combined with a possible pip check cf #2492

[anntzer]

While this may work, this would require a install first (possibly lengthy, if there are compiled modules), even though the information is actually available before the actual install step.
I guess this really means, though, that the missing tool is more something like pip show for not-installed packages.

[dstufft]

I'm going to close this issue. While I recognize that there are some cases when this might be useful, I believe that the cases where this is useful are sufficiently in the minority that adding the additional overhead (both code and mental) of a new option is not something that we want to do to support it.