Why are useful command line options in pip undocumented and explicitly hidden?

I use export PIP_REQUIRE_VIRTUALENV=true; in my .bashrc to ensure that I do not accidentally pollute my global env while installing packages for the various projects I work on.

I vaguely remembered that this was the same as adding a --require-virtualenv to the command line while invoking pip.

However, I was unable to find any documentation for this anywhere except in the source code, where help for the feature is explicitly suppressed (using SUPRESS_HELP)! There are 11 such options for which the help has also been explicitly disabled (e.g. --no-input).

I look through the history of the file, but did not find any mention of why the feature was hidden in the commit messages.

Is this an experimental feature which should not be relied upon? Should I not use (nor encourage others to use) these features or is there a different way of using these features? Could someone please shine some light on this conundrum?

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This is a question which I had previously posted on StackOverflow hoping that there was an explanation along the lines that these options were only to be used if pip was invoked from other dependency management software.

However, that doesn’t seem to be case, or at least it isn’t common knowledge.

[chrahunt]

To be specific, in the current version of pip these are the hidden options:

Name	Location	Note
--require-virtualenv	link	added in 301dc31, no explanation
--no-input	link	added in 4d33521, no explanation
--skip-requirements-regex	link	added in 5aa4be, no explanation - deprecated in #7297
--no-use-pep517	link	this was done in #5743 here probably just to remove any redundancy with --use-pep517
--always-unzip	link	Commented with “Deprecated, remove later”, looks like it is a no-op
install --no-user	link	#5116 indicates it needed more thought before exposing

[deveshks]

I have created issue #8408 to get rid of --always-unzip from pip source. If this is something we are looking to do, I can go ahead and create a PR for it.

https://github.com/pypa/pip/pull/8470 is created for this.