Impossible to install Black 19.3b0

• OS version and name: elementary OS 0.4.1 Loki
• Poetry version: 0.12.17
• Link of a Gist with the contents of your pyproject.toml file: https://github.com/Xowap/typefit/blob/develop/pyproject.toml

Issue

I’m trying to install Black, and I’m kind of succeeding thanks to comments in #767. However, the version of Black I’m getting is not the latest one:

> poetry run black --version
black, version 18.9b0

The latest one being 19.3b0.

I was wondering if this could be due to black not respecting semver, so I put the version number manually to see what happens, but turns out it’s not helping much.

black = {version = "19.3b0", allows-prereleases = true}

[SolverProblemError]                                                                    
Because typefit depends on black (19.3b0) which doesn't match any versions, version solving failed.

Thanks for your help!

[hitshydev]

I’m experiencing a similar problem by trying to add essentia to my dependencies. I’m also using elementary OS. But I solved it, here is how:

I edited the first line of ~/.poetry/bin/poetry to #!/usr/bin/env python3

Here is some explanation: elementary OS comes with preinstalled python 2.x , that’s why the python environment variable is already occupied and one has to run sudo apt install python3 to get python 3.x which then occupies the python3 environment variable. I would guess that many ubuntu based systems are installing python 3.* in this way that’s why sometimes poetry won’t run at all or is behaving in an unexpected manner. But that said, the bug can only be reproduced when running poetry with python 2.x (2.7 in my case).

[Rosswell]

I can’t reproduce either. poetry init resulted in

[tool.poetry]
name = "test"
version = "0.1.0"
description = ""
authors = ["Your Name <[e-mail]>"]

[tool.poetry.dependencies]
python = "^3.7"

[tool.poetry.dev-dependencies]

[build-system]
requires = ["poetry>=0.12"]
build-backend = "poetry.masonry.api"

then using the same command for installation

$ poetry add -D --allow-prereleases black
Creating virtualenv test-wix2tCvA-py3.7 in /Users/rblanchard/Library/Caches/pypoetry/virtualenvs
Using version ^19.10b0 for black

Updating dependencies
Resolving dependencies... (1.0s)

Writing lock file


Package operations: 8 installs, 0 updates, 0 removals

  - Installing appdirs (1.4.3)
  - Installing attrs (19.3.0)
  - Installing click (7.0)
  - Installing pathspec (0.6.0)
  - Installing regex (2019.12.19)
  - Installing toml (0.10.0)
  - Installing typed-ast (1.4.0)
  - Installing black (19.10b0)

$ poetry --version
Poetry version 1.0.0
$ python3 -V
Python 3.7.4