Source code:Lib/venv/
The
venv module provides support for creating lightweight “virtualenvironments” with their own site directories, optionally isolated from systemsite directories. Each virtual environment has its own Python binary (whichmatches the version of the binary that was used to create this environment) andcan have its own independent set of installed Python packages in its sitedirectories.
In the settings window, you will now configure the default projects you make in PyCharm to use Python 3. When the setting dialog comes up, select the Project Interpreter to choose the Python 3 interpreter that you just installed. Turn off the default use of venv for projects. You should see a settings button (e.g. Gear) for adding an interpreter. Python interpreter free download - Python Interpreter, Python Programming Interpreter, Python, and many more programs. Enter to Search. My Profile Logout. Python 2.7, python 3.4. Python for Windows, Linux/UNIX, Mac OS X, Other. Want to help test development versions of Python? Prereleases, Docker images. Looking for Python 2.7? See below for specific releases Active Python Releases. 2014 Download Release Notes; Python 3.4.1 May 19, 2014 Download Release Notes; Python 3.4.0 March 17, 2014 Download Release Notes. Double-click the icon labeling the file python-3.4.1-macosx10.6.dmg. A file folder named Python 3.4.1 containing the Python.mpkg file will appear. Control-click on the Python.mpkg file and select open. If the following pop-up window appears enter you password and click Install Python. An Install Python pop-up window will appear. Click Continue button.
See PEP 405 for more information about Python virtual environments.
See also
Creating virtual environments¶
Creation of virtual environments is done by executing thecommand
venv :
Running this command creates the target directory (creating any parentdirectories that don’t exist already) and places a
pyvenv.cfg file in itwith a home key pointing to the Python installation from which the commandwas run (a common name for the target directory is .venv ). It also createsa bin (or Scripts on Windows) subdirectory containing a copy/symlinkof the Python binary/binaries (as appropriate for the platform or argumentsused at environment creation time). It also creates an (initially empty)lib/pythonX.Y/site-packages subdirectory (on Windows, this isLibsite-packages ). If an existing directory is specified, it will bere-used.
Deprecated since version 3.6:
pyvenv was the recommended tool for creating virtual environments forPython 3.3 and 3.4, and is deprecated in Python 3.6.
Changed in version 3.5: The use of
venv is now recommended for creating virtual environments.
On Windows, invoke the
venv command as follows:
Alternatively, if you configured the
PATH and PATHEXT variables foryour Python installation:
The command, if run with
-h , will show the available options:
Python 2.7 Interpreter Download
Changed in version 3.8: Add
--upgrade-deps option to upgrade pip + setuptools to the latest on PyPI
Changed in version 3.4: Installs pip by default, added the
--without-pip and --copies options
Changed in version 3.4: In earlier versions, if the target directory already existed, an error wasraised, unless the
--clear or --upgrade option was provided.
Note
While symlinks are supported on Windows, they are not recommended. Ofparticular note is that double-clicking
python.exe in File Explorerwill resolve the symlink eagerly and ignore the virtual environment.
Note
On Microsoft Windows, it may be required to enable the
Activate.ps1 script by setting the execution policy for the user. You can do this byissuing the following PowerShell command:
PS C:> Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser
See About Execution Policiesfor more information.
The created
pyvenv.cfg file also includes theinclude-system-site-packages key, set to true if venv isrun with the --system-site-packages option, false otherwise.
Unless the
--without-pip option is given, ensurepip will beinvoked to bootstrap pip into the virtual environment.
Multiple paths can be given to
venv , in which case an identical virtualenvironment will be created, according to the given options, at each providedpath.
Once a virtual environment has been created, it can be “activated” using ascript in the virtual environment’s binary directory. The invocation of thescript is platform-specific (<venv> must be replaced by the path of thedirectory containing the virtual environment):
You don’t specifically need to activate an environment; activation justprepends the virtual environment’s binary directory to your path, so that“python” invokes the virtual environment’s Python interpreter and you can runinstalled scripts without having to use their full path. However, all scriptsinstalled in a virtual environment should be runnable without activating it,and run with the virtual environment’s Python automatically.
You can deactivate a virtual environment by typing “deactivate” in your shell.The exact mechanism is platform-specific and is an internal implementationdetail (typically a script or shell function will be used).
New in version 3.4:
fish and csh activation scripts.
New in version 3.8: PowerShell activation scripts installed under POSIX for PowerShell Coresupport.
Note
A virtual environment is a Python environment such that the Pythoninterpreter, libraries and scripts installed into it are isolated from thoseinstalled in other virtual environments, and (by default) any librariesinstalled in a “system” Python, i.e., one which is installed as part of youroperating system.
A virtual environment is a directory tree which contains Python executablefiles and other files which indicate that it is a virtual environment.
Xmind mac free. Common installation tools such as setuptools and pip work asexpected with virtual environments. In other words, when a virtualenvironment is active, they install Python packages into the virtualenvironment without needing to be told to do so explicitly.
When a virtual environment is active (i.e., the virtual environment’s Pythoninterpreter is running), the attributes
sys.prefix andsys.exec_prefix point to the base directory of the virtualenvironment, whereas sys.base_prefix andsys.base_exec_prefix point to the non-virtual environment Pythoninstallation which was used to create the virtual environment. If a virtualenvironment is not active, then sys.prefix is the same assys.base_prefix and sys.exec_prefix is the same assys.base_exec_prefix (they all point to a non-virtual environmentPython installation).
When a virtual environment is active, any options that change theinstallation path will be ignored from all
distutils configurationfiles to prevent projects being inadvertently installed outside of thevirtual environment.
When working in a command shell, users can make a virtual environment activeby running an
activate script in the virtual environment’s executablesdirectory (the precise filename and command to use the file isshell-dependent), which prepends the virtual environment’s directory forexecutables to the PATH environment variable for the running shell. Thereshould be no need in other circumstances to activate a virtualenvironment; scripts installed into virtual environments have a “shebang”line which points to the virtual environment’s Python interpreter. This meansthat the script will run with that interpreter regardless of the value ofPATH . On Windows, “shebang” line processing is supported if you have thePython Launcher for Windows installed (this was added to Python in 3.3 - seePEP 397 for more details). Thus, double-clicking an installed script in aWindows Explorer window should run the script with the correct interpreterwithout there needing to be any reference to its virtual environment inPATH .
API¶
The high-level method described above makes use of a simple API which providesmechanisms for third-party virtual environment creators to customize environmentcreation according to their needs, the
EnvBuilder class.
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