module pycode.venv_helper

Short summary

module pyquickhelper.pycode.venv_helper

Helpers for virtualenv

New in version 1.2.

Classes

class	truncated documentation
NotImplementedErrorFromVirtualEnvironment	defines an exception when a function does not work in a virtual environment .. versionadded:: 1.3
VirtualEnvError	exception raised by the function implemented in this file

Functions

function	truncated documentation
build_venv_cmd	builds the command line for virtual env
check_readme_syntax	check the syntax of the file readme.rst which describes a python project
compare_module_version	compare two versions
create_virtual_env
is_virtual_environment	tells if the script is run from a virtual environment
numeric_module_version	convert a string into a tuple with numbers whever possible
run_venv_script	run a script on a vritual environment (the script should be simple
venv_install	install a package or a list of packages in a virtual environment

Documentation

Helpers for virtualenv

New in version 1.2.

exception pyquickhelper.pycode.venv_helper.NotImplementedErrorFromVirtualEnvironment

Bases: NotImplementedError

defines an exception when a function does not work in a virtual environment

New in version 1.3.

exception pyquickhelper.pycode.venv_helper.VirtualEnvError

Bases: Exception

exception raised by the function implemented in this file

pyquickhelper.pycode.venv_helper.build_venv_cmd(params, posparams)

builds the command line for virtual env

Parameters:

• params – dictionary of parameters
• posparams – positional arguments

Returns:

string

pyquickhelper.pycode.venv_helper.check_readme_syntax(readme, folder, version='0.8', fLOG=<function noLOG at 0x00000210845D3950>)

check the syntax of the file readme.rst which describes a python project

Parameters:

• readme – file to check
• folder – location for the virtual environment
• version – version of docutils
• fLOG – logging function

Returns:

output or SyntaxError exception

pipy server is based on docutils ==0.8. The most simple way to check its syntax is to create a virtual environment, to install docutils==0.8 and to compile the file. This is what this function does.

Unfortunately, this functionality does not work yet from a virtual environment.

New in version 1.3.

pyquickhelper.pycode.venv_helper.compare_module_version(num, vers)

compare two versions

Parameters:

• num – first version
• vers – second version

Returns:

-1, 0, 1

Changed in version 1.3: Fix a bug (do not use ModuleInstall)

pyquickhelper.pycode.venv_helper.create_virtual_env(where, symlinks=False, system_site_packages=False, clear=True, packages=None, fLOG=<function noLOG at 0x00000210845D3950>, temp_folder=None)

create a virtual environment

Parameters:

• where – location of this virtual environment
• symlinks – attempt to symlink rather than copy
• system_site_packages – Give the virtual environment access to the system site-packages dir
• clear – Delete the environment directory if it already exists. If not specified and the directory exists, an error is raised.
• packages – list of packages to install (it will install module pymyinstall).
• fLOG – logging function
• temp_folder – temporary folder (to download module if needed), by default <where>/download

Returns:

stand output

How to create a virtual environment?

The following example creates a virtual environment. Packages can be added by specifying the parameter package.

from pyquickhelper.pycode import create_virtual_env
fold = "my_env"
if not os.path.exists(fold):
    os.mkdir(fold)
create_virtual_env(fold)

The function does not work from a virtual environment.

pyquickhelper.pycode.venv_helper.is_virtual_environment()

tells if the script is run from a virtual environment

Returns:boolean

New in version 1.3.

pyquickhelper.pycode.venv_helper.numeric_module_version(vers)

convert a string into a tuple with numbers whever possible

Parameters:vers – string Returns:tuple

pyquickhelper.pycode.venv_helper.run_venv_script(venv, script, fLOG=<function noLOG at 0x00000210845D3950>, file=False, is_cmd=False, skip_err_if=None)

run a script on a vritual environment (the script should be simple

Parameters:

• venv – virtual environment
• script – script as a string (not a file)
• fLOG – logging function
• file – is script a file or a string to execute
• is_cmd – if True, script is a command line to run (as a list) for python executable
• skip_err_if – do not pay attention to standard error if this string was found in standard output

Returns:

output

The function does not work from a virtual environment.

pyquickhelper.pycode.venv_helper.venv_install(venv, packages, fLOG=<function noLOG at 0x00000210845D3950>, temp_folder=None)

install a package or a list of packages in a virtual environment

Parameters:

• venv – location of the virtual environment
• packages – a package (str) or a list of packages(list[str])
• fLOG – logging function
• temp_folder – temporary folder (to download module if needed), by default <where>/download

Returns:

standard output

The function does not work from a virtual environment.