The documentation for urlencode() [1] isn't very clear on how the safe parameter is used, it would better not list it together with encoding and error as only applying to strings.

[1] https://docs.python.org/3.5/library/urllib.parse.html#urllib.parse.urlencode

The current documentation looks very clear to me, and I don't understand your changed version.  Can you give an example of how the existing text is inaccurate or results in confusion?

I was looking at the sentence:
"When query parameter is a str, the safe, encoding and error parameters are passed down to quote_plus() for encoding."

The query argument can't be a string itself (gives a TypeError with 3.5a0 and I think it's only intended to accept dicts or sequences of 2-tuples). The "parameter" then must refer to a component of the query -- a key or a value.

The safe argument is passed down and is effective no matter if a component is of str or bytes type (or a sequence with doseq), for example:

>>> urlencode({b'/ n': ''}, safe='/')
'/+n='
(note the "b"; without "safe" the slash would get encoded as %2F).

Maybe it would also be good to change "query parameter" to "query component" in that sentence.

OK, now I understand.  How about this phrasing:

"The *safe*, *encoding*, and *error* parameters are passed down to :func:`quote_plus` (the *encoding* and *error* parameters are only passed when the query element is a :class:`str`).

Thanks, that's right and better, as it doesn't replicate the safe explanation.

I've just noticed another small one, the docstring for quote() [2] says:
"encoding must not be specified if string is a str" -- that should be "... is a bytes".

[2] https://hg.python.org/cpython/file/default/Lib/urllib/parse.py#l690

Updated the patch, additionally changing "be" to "contain" in the first sentence.

New changeset 126aff7c6a33 by R David Murray in branch '3.4':
#23040: Clarify treatment of encoding and errors when component is bytes.
https://hg.python.org/cpython/rev/126aff7c6a33

New changeset 367ba031a743 by R David Murray in branch 'default':
Merge: #23040: Clarify treatment of encoding and errors when component is bytes.
https://hg.python.org/cpython/rev/367ba031a743

Thanks, Wojtek.