Misuse of $ in activate.fish of venv

[ghost]

BPO	26664
Nosy	@brettcannon, @vsajip, @Tinche, @zhangyangyu, @karolyi
Files	screenshot.png: error message

^{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 = 'https://github.com/brettcannon'
closed_at = <Date 2016-06-30.18:46:36.409>
created_at = <Date 2016-03-29.12:46:25.349>
labels = ['type-bug', 'library']
title = 'Misuse of $ in activate.fish of venv'
updated_at = <Date 2016-07-01.12:14:45.209>
user = None

bugs.python.org fields:

activity = <Date 2016-07-01.12:14:45.209>
actor = 'karolyi'
assignee = 'brett.cannon'
closed = True
closed_date = <Date 2016-06-30.18:46:36.409>
closer = 'brett.cannon'
components = ['Library (Lib)']
creation = <Date 2016-03-29.12:46:25.349>
creator = '\xe9\x84\xad\xe6\x99\xaf\xe6\x96\x87'
dependencies = []
files = ['42321']
hgrepos = []
issue_num = 26664
keywords = []
message_count = 18.0
messages = ['262609', '262620', '262748', '262917', '264328', '264330', '264383', '269610', '269612', '269615', '269616', '269618', '269620', '269625', '269627', '269628', '269639', '269661']
nosy_count = 8.0
nosy_names = ['brett.cannon', 'vinay.sajip', 'python-dev', 'tinchester', 'xiang.zhang', '\xe9\x84\xad\xe6\x99\xaf\xe6\x96\x87', 'erdban fed', 'karolyi']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue26664'
versions = ['Python 3.5', 'Python 3.6']

[ghost]

I use venv module to make a virtual environment in cpython3.6.
After it, I try to activate it with fish, but it give me an error, like the screenshot.
I open the activate.fish and remove the $ sign in line 58 and 59, then the activate file works.
I open the activate.fish of py3.5 venv, there isn't a $ sign in line 58 and 59, too.
However, there is a bug issue which add the $ in front of the prompt.
I'm not sure how this happen, but I think there should not be a $ there.

[vsajip]

The change you mention was in response to Issue bpo-26348. The patch supplied there introduced the $ characters you say aren't required. I'm not a fish user, but it would seem that "$VENV_PROMPT" would resolve to the *value* of the environment variable __VENV_PROMPT__, whereas "__VENV_PROMPT__" would just resolve to the literal string "__VENV_PROMPT__" which doesn't seem like what is wanted. Can you explain the reasoning by which you assert that the $ isn't wanted?

[ghost]

First, I use python 3.5.1 to create virtual environment. It works fine with fish. There is no $ in the activate.fish file.
Second, after I removed the $, It works fine, both in ubuntu and arch linux.

I guess it is because the $ is for bash not for fish, the activate.fish didn't work.
These are why I assert the $ is unwanted.

[vsajip]

I've asked the person who sent in the patch for bpo-26348 to comment on this issue.

[Tinche]

I'm getting this exact issue on Python 3.5 (xenial system installation).

All my existing venvs (from before my upgrade to xenial) work. Here's the diff:

diff .venv/bin/activate.fish ../wrapt/.venv/bin/activate.fish
35c35
< set -gx VIRTUAL_ENV "/home/tin/pg/hypothesis/.venv"
---
set -gx VIRTUAL_ENV "/home/tin/pg/wrapt/.venv"
58,59c58,59
< if test -n "$(.venv) "
< printf "%s%s%s" "$(.venv) " (set_color normal) (_old_fish_prompt)
---
if test -n "(.venv) "
printf "%s%s%s" "(.venv) " (set_color normal) (_old_fish_prompt)

The added dollar signs are the issue. Removing them fixes the problem.

For the record:

fish --version
fish, version 2.2.0

And here's the actual error message, the same as in the png:

. .venv/bin/activate.fish
$(...) is not supported. In fish, please use '(.venv)'.
.venv/bin/activate.fish (line 58): if test -n "$(.venv) "
^
from sourcing file .venv/bin/activate.fish
called on line 151 of file /usr/share/fish/config.fish

in function “.”
called on standard input

source: Error while reading file “.venv/bin/activate.fish”

[Tinche]

Also I will add I've been using fish for a long time and have never been affected by bpo-26348.

[zhangyangyu]

The patch introduced by bpo-26348 should be reverted. The __VENV_PROMPT__ is meant to be a placeholder. For example, when you create a virtual environment named venv-test, the __VENV_PROPMT__ will be replace by (venv-test). If the patch is applied, it will be $(venv-test), treated as an expression and then cause a failure.

[erdbanfed]

This bug shipped in 3.5.2. It should've been a blocker.

[zhangyangyu]

I get the same feeling. Add Larry.

[python-dev]

New changeset 8d7bde14d7a4 by Brett Cannon in branch 'default':
Merge from 3.5 for issue bpo-26664
https://hg.python.org/cpython/rev/8d7bde14d7a4

[brettcannon]

Two things.

One, sorry for not getting to this before 3.5.1 got out. It simply slipped off my radar thanks to various other issues that I've been dealing with. It's obviously now fixed.

Two, this is not a release blocker. Python itself continues to function properly with this bug and it doesn't prevent you from working with a venv under fish (but I recognize it's an annoyance).