Assignment expression symbol (walrus) not in built-in help()

[Carreau]

BPO	37082
Nosy	@gvanrossum, @terryjreedy, @Carreau, @emilyemorehouse, @pablogsal, @tirkarthi

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2019-05-28.18:26:23.297>
labels = ['3.8', '3.9', 'docs']
title = 'Assignment expression symbol (walrus) not in built-in help()'
updated_at = <Date 2021-08-22.13:18:41.317>
user = 'https://github.com/Carreau'

bugs.python.org fields:

activity = <Date 2021-08-22.13:18:41.317>
actor = 'mark.dickinson'
assignee = 'docs@python'
closed = False
closed_date = None
closer = None
components = ['Documentation']
creation = <Date 2019-05-28.18:26:23.297>
creator = 'mbussonn'
dependencies = []
files = []
hgrepos = []
issue_num = 37082
keywords = []
message_count = 6.0
messages = ['343813', '343868', '343869', '343871', '344131', '374280']
nosy_count = 7.0
nosy_names = ['gvanrossum', 'terry.reedy', 'docs@python', 'mbussonn', 'emilyemorehouse', 'pablogsal', 'xtreak']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = None
url = 'https://bugs.python.org/issue37082'
versions = ['Python 3.8', 'Python 3.9']

Linked PRs

• gh-81263: Add assignment expressions to help #124641
• [3.13] gh-81263: Add assignment expressions to help (GH-124641) #124713

[Carreau]

Do the following at a Python prompt:

>>> help()

Welcome to Python 3.8's help utility!

[...]SNIP

help> symbols

Here is a list of the punctuation symbols which Python assigns special meaning
to. Enter any symbol to get more help.

!=                  +                   <=                  __
"                   +=                  <>                  `
"""                 ,                   ==                  b"
%                   -                   >                   b'
%=                  -=                  >=                  f"
&                   .                   >>                  f'
&=                  ...                 >>=                 j
'                   /                   @                   r"
'''                 //                  J                   r'
(                   //=                 [                   u"
)                   /=                  \                   u'
*                   :                   ]                   |
**                  <                   ^                   |=
**=                 <<                  ^=                  ~
*=                  <<=                 _

Oh no ! Our favorite := is missing :-(

[mdickinson]

Looks like that list could do with some attention:

• I don't see regular assignment there, either.
• And "`" shouldn't be in that list.
• Neither should "<>"
• "->" (for function annotations) is missing.

[mdickinson]

@= is also missing. Looks like we need to go through the grammar and reconcile what's there with the symbols help.

[tirkarthi]

Seems this was added in db7b6b9 (2009) and wasn't updated from then.

[terryjreedy]

The augmented assignment symbol, like that for plain assignment, is not, properly speaking, an operator. But it definitely is a symbol that needs to be documented.

1. Generally update the help symbol list.

2. Document :=, assignment expression, in the regular docs, but I found nothing.

':=' should be on https://docs.python.org/3.8/genindex-Symbols.html just ':(colon)'.

'expression' should be listed under 'assignment on
https://docs.python.org/3.8/genindex-A.html

I think 'assignment' should be listed under 'expression' on
https://docs.python.org/3.8/genindex-E.html

I could not find anything in the expressions chapter.

[gvanrossum]

We might get more help with this issue if the process of updating the help() output were better documented. I recently looked into what it would take to add "FSTRINGS" to the "topics" list, and it's quite complicated -- I only persevered after stepping through pydoc.help() using pdb. I wrote up a few tips in bpo-41045.

[emilyemorehouse]

Fixed via #124641 (finally 🎉)