121

When a project is specified only via pyproject.toml (i.e. no setup.{py,cfg} files), how can it be installed in editable mode via pip (i.e. python -m pip install -e .)?

I tried both setuptools and poetry for the build system, but neither worked:

[build-system] requires = ["setuptools", "wheel"] build-backend = "setuptools.build_meta" 
[build-system] requires = ["poetry-core>=1.0.0"] build-backend = "poetry.core.masonry.api"

I get the same error for both build systems:

ERROR: Project file:///tmp/demo has a 'pyproject.toml' and its build backend is missing the 'build_editable' hook. Since it does not have a 'setup.py' nor a 'setup.cfg', it cannot be installed in editable mode. Consider using a build backend that supports PEP 660.

I'm using this inside a conda environment, the following is my version of setuptools and pip:

$ conda list | grep setuptools setuptools 58.3.0 pypi_0 pypi $ python -m pip --version pip 21.3.1
Improve this question

6 Answers 6

Reset to default
106

I stumbled here as I searched for the error string "(A "pyproject.toml" file was found, but editable mode currently requires a setuptools-based build.)"

In my case, all I needed to do was update pip:

python3 -m pip install --upgrade pip

Then the install worked fine.

Improve this answer
Sign up to request clarification or add additional context in comments.

Comments

104

PEP 660 – Editable installs for pyproject.toml based builds defines how to build projects that only use pyproject.toml. Build tools must implement PEP 660 for editable installs to work. You need a front-end (such as pip ≥ 21.3) and a backend. The statuses of some popular backends are:

Note: To be able to do an editable installation to your user site (pip install -e --user), you need a system installed setuptools v62.0.0 or newer.

Improve this answer

9 Comments

I find it incredibly confusing that "implements PEP 660" seems to mean "frontend which supports PEP 660-compliant backends". Practically, one needs both the frontend and the backend. The only compliant backend I've been able to find so far is Flit. The Poetry implementation has still not been released. From what I can tell, pip is just a frontend There seems to be no implementation yet for setuptools.
PEP 660 is implemented in poetry 1.0.8
Pip supports editable installs from pyproject.toml files since 21.3
Maybe hatch, pdm, and whey could be on this list. As far as I can tell, they are all PEP 660-compatible.
To avoid the "system installed setuptools" requirement, you can do a non-isolated build as well (e.g., with --no-build-isolation)
|
25

Note: This workaround is no longer required. Setuptools supports editable installations since v64.0.0 (Aug 2022). Old answer remains below for people stuck on older setuptools versions for whatever reason...

As a temporary workaround until setuptools implements PEP 660 (#2816) you can create an empty setup file just for the purpose of the editable installation.

touch setup.cfg pip install -e . rm setup.cfg

Note: this is not actually invoking any build_editable hook (which doesn't even exist in setuptools' backend currently), instead it triggers a code path within pip which creates a temporary setup.py and then executes setup.py develop. So it's a "legacy" editable installation, done by putting down a link to the source code in a path configuration file like .venv/lib/python3.XY/site-packages/easy-install.pth. Poetry and flit do similar, except they're creating separate path files like mypkg.pth in the site dir, rather than using lines in easy-install.pth.

Because setup.py develop is a path file hack, the usual caveats of such development installs apply, e.g. it exposes any .py files which happen to be present in the source directory even if they are not actually packaged into a real distribution when creating a release.

Improve this answer

5 Comments

Thanks! It does seem to work, but why? Do you have any explanation at hand?
See how pip checks whether the build backend supports editable installation
I am getting (path) does not appear to be a Python project: neither 'setup.py' nor 'pyproject.toml' found.
This workaround is scheduled to stop working in Pip 25.1 (due in April) since it deliberately tries to trigger a "legacy editable install".
@User15239563 of course it won't work with only an empty setup.cfg. The question is about projects that also have a pyproject.toml.
2

As of poetry 1.2.0b3, "current project" is automatically installed in editable mode by default when you run poetry install.

$ pip uninstall virtualenv # or via apt if you installed that way $ sudo apt install python3-dev python3-pip python3-setuptools $ wget install.python-poetry.org -o get-poetry.py $ python3 get-poetry.py --preview $ cd /you/project/folder $ poetry install $ pip list Package Version Editable project location ------------------ -------- ------------------------------------------- ... your-project 0.1.0 /you/project/folder pip 22.2.2 ...
Improve this answer

Comments

1

With a minimalistic pyproject.toml

[project] name = "proj_name" version = "0.1.0" dependencies = []

And this file structure

proj_name ├── pyproject.toml └── proj_name └── code.py

You can use Setuptool's legacy behavior (Note: will be removed in future versions❗)

pip install -e . --config-settings editable_mode=compat

Which lets you import like this!

from proj_name.code import your_func
Improve this answer

Comments

-4

Found a great resource here:

https://setuptools.pypa.io/en/latest/userguide/quickstart.html#development-mode

pip install --editable .
Improve this answer

Comments

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.