pyvenv

This is a conan python_requires package, exposing functionality to create and manage python virtual environments.

This package exposes a number of modules:

• PythonVirtualEnv: Construct a PythonVirtualEnv object. This will allow you to set up a new virtual environment, or manage an existing one.
• create: Create a virtual environment
• setup_entry_points: Create an entry point for a package installed in the virtual environment
• entry_points: Retrieve the entry points associated with a particular package in the virtual environment
• which: Retrieve the path to an executable within the virtual environment
• args_to_string: Convert a list of arguments to a command line string in an operating system agnostic way
• make_relocatable: Patch files in the virtualenv such that it can be relocated on the local file system.

Usage

Create a new python virtual environment:

class PythonVirtualEnvironment(ConanFile):
    python_requires = "pyvenv/[>=0.2.2]@mtolympus/stable"

    def package(self):
        requirements = ["sphinx==4.4.0", "sphinx_rtd_theme=0.5.3", "matplotlib==3.5.0"]
        args_to_string = self.python_requires["pyvenv"].module.args_to_string
        venv = self.python_requires["pyvenv"].module.PythonVirtualEnv(self)

        # You can use any of the following methods to install packages into the virtualenv
        venv.create(folder=os.path.join(self.package_folder), requirements=requirements)
        self.run(args_to_string([venv.python, "-mpip", "install", "sphinx-multiversion"], scope="conanbuild")
        with venv.activate():
            # NOTE: Do not use `venv.pip` outside of an `activate` block - it will embed the incorrect interpreter
            # into the script
            self.run(args_to_string([venv.pip, "install", "black"], scope="conanbuild")

        venv.setup_entry_points("sphinx", os.path.join(self.package_folder, "bin"))
        venv.make_relocatable(env_folder=self.package_folder) # Only needs to be run when packages are installed outside of `venv.create()`

Manage an existing python virtual environment:

from pathlib import Path

class PythonVirtualEnvironment(ConanFile):
    python_requires = "pyvenv/[>=0.2.2]@mtolympus/stable"

    @property
    def binpath(self):
        return "Scripts" if sys.platform == "win32" else "bin"

    def package(self):
        python_envdir = Path(Path.home(), "venv")
        path = Path(python_envdir, self.binpath, "python")
        realname = path.resolve(strict=True).name
        interpreter = str(path.with_name(realname))
        venv = self.python_requires["pyvenv"].module.PythonVirtualEnv(
            self._conanfile,
            interpreter=interpreter,
            env_folder=python_envdir,
        )

        entry_points = venv.entry_points("sphinx")
        # Get the names of the sphinx executables, i.e. sphinx-build, sphinx-quickstart, sphinx-apidoc, sphinx-autogen
        console_scripts = entry_points.get("console_scripts", []) 

An example of a package that uses this is the python-virtualenv/system package.

See also the CMakePythonDeps generator, which is designed to be used in conjunction with PythonVirtualEnv.

This has been developed with significant inspiration from, and uses pyvenv code largely developed by thorntonryan/conan-pyvenv, and modified by Samuel Dowling.