This is a safeguard against typos when running
pip install -r requirements-dev.txt.
If you leave out the
-r by accident, this package will cause your installation
$ pip install requirements-dev.txt Collecting requirements-dev.txt Installing collected packages: requirements-dev.txt Running setup.py install for requirements-dev.txt ... error Complete output from command: running install It looks like you meant to type `pip install -r requirements-dev.txt`, but you left out the `-r` by accident. Aborting installation.
If we had no such package on PyPI, you could accidentally install a package installed with the name of your requirements file. A malicious user could register a package that would mimic proper installation process and also launch anny arbitrary code.
PyPI (fortunately) does not allow
requirements.txt as a package name, so that
case is handled already. All forbidden package names that are
hardcoded in PyPI source code
But it obviously does not cover all popular cases. This is why this sources are distributed on PyPI under few popular names that are not forbidden by PyPI:
Did it ever happen?
Yeah. Typo squatting happens on PyPI from time to time. This project is the
best example of that. Previous version of
requirements.txt actually did
something more than aborting its installation. It provided a specially
setup.py script that could:
- look on your filesystem to find a requirements file you intended to install
- install all packages in another pip subprocess
- display output that would mimick normal installation process
Newer versions of pip completely swallow all output of package installation
script but thih behavior can be easily bypassed - at least on OS X and Linux.
Also runtime version switch (to
0.0.0) allowed to install this package over
and over becasue there was always newer version available on PyPI. If something
went wrong (especially on Windows) it resulted in crypting and rude error message.
Nothing harmful. Actually useful sometimes. At least in my personal opinion.
Anyway my sense of usability and humour
was contested by some people.
This is why
requirements.txt will longer install other packages and always
exit with error code during installation. This is mostly thanks to pull-request
from @aanand and his points.
I may not agree with all of them but I respect people's PRs.
Nevertheless, some additional messages may be displayed during installation attempt. You know... It was made for fun.
If you are interested in hacks included in previous version of this package
contested-sense-of-humour branch or
end-of-fun tag in this