frontend-editables 0.1.0

A library for installing distributions in editable mode.

This is a PoC of an editable library which operates on the frontend as discussed on the Python packaging Discourse. It supports installing prospective editable distributions using three different methods (symlink, redirector and .pth files) and two strategies (lax and strict). The strict strategy reproduces the distribution structure faithfully whereas the lax strategy exposes the contents of packages as they appear on disk. The input must be a mapping of would-be wheel file paths and absolute paths on disk; folder paths are invalid. This library does not manipulate data files or scripts because I consider that to be an unnecessary complication in the context of editable installation.

Installation

$ python -m pip install frontend-editables

Basic usage

import sysconfig

import frontend_editables

path_mapping = ...  # Will have been returned by the backend.
installed_files = frontend_editables.install(
    "name",
    sysconfig.get_path("purelib"),
    path_mapping,
    frontend_editables.EditableStrategy.lax,
)
# Then append the ``installed_files`` to the distribution's ``RECORD``,
# optionally by passing ``append_to_record=<path to RECORD>`` to ``install``.

CLI

frontend_editables includes an extremely hacky CLI which serves a stopgap until editable installation is standardised. You can use this in place of python -m pip install -e .... The CLI supports all of the same layouts and installation methods supported by the library. Some examples:

• To install a project with a single module foo.py, symlinking it: python -m frontend_editables.transitional_cli --strategy strict foo.py foo.py.

• To install a project with a package foo, located in <project-root>/src/foo, with the aid of a pth file: python -m frontend_editables.transitional_cli --method pth_file src/foo foo.

• To install a project with multiple packages at different locations: python -m frontend_editables.transitional_cli {src/,}foo {lib/,}bar

Editable distributions can be uninstalled with pip as normal.

usage: python -m frontend_editables.transitional_cli [-h]
                                                     [--method {symlink,redirect,pth_file}]
                                                     [--strategy {lax,strict}]
                                                     [--spec SPEC]
                                                     path_pairs
                                                     [path_pairs ...]

Wacky transitional editable project installer.

positional arguments:
  path_pairs            pairs of path on disk and corresponding path in
                        the virtual wheel (posix)

optional arguments:
  -h, --help            show this help message and exit
  --method {symlink,redirect,pth_file}
                        editable installation method to use (default:
                        None)
  --strategy {lax,strict}
                        editable strategy to follow (default: lax)
  --spec SPEC           requirement specifier (default: .)

Contributing

You can use frontend-editables to install frontend-editables for development:

$ PYTHONPATH=src python -m frontend_editables.transitional_cli \
    --spec .[test] {src/,}frontend_editables

Before opening a merge request, install nox and run nox. The type checking step has an external dependency on npm.

Happy hacking!