[docs] [issue33581] Document "optional components that are commonly included in Python distributions."

[Antony Lee]

New submission from Antony Lee <anntzer.lee at gmail.com>:

The stdlib docs intro include the following sentences:

    It also describes some of the optional components that are commonly included in Python distributions.

    For Unix-like operating systems Python is normally provided as a collection of packages, so it may be necessary to use the packaging tools provided with the operating system to obtain some or all of the optional components.

However, as far as I can tell, there is no easy way to actually know what parts of the stdlib are "optional".  The _thread module's doc does state "The module is optional.", and the threading module's doc also implies that it is optional ("The dummy_threading module is provided for situations where threading cannot be used because _thread is missing.") (yes, I know support for threadless builds is going away in 3.7; that's irrelevant here.), but even ensurepip's docs don't state that it may be missing (even though I believe(?) that it is indeed removed (and intended to be so) from some linux distribution's Pythons).

A master list of "optional" features would thus be welcome.  Its usefulness is to know what parts of the stdlib we can actually rely on; e.g. in https://github.com/matplotlib/matplotlib/issues/10866 a Matplotlib user noted that bz2 is not present in all Python installs.

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assignee: docs at python
components: Documentation
messages: 317140
nosy: Antony.Lee, docs at python
priority: normal
severity: normal
status: open
title: Document "optional components that are commonly included in Python distributions."

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