three. Using Python on Windows¶

This certificate aims to give an overview of Windows-specific behaviour yous should know almost when using Python on Microsoft Windows.

iii.ane. Installing Python¶

Different most Unix systems and services, Windows does not include a arrangement supported installation of Python. To make Python available, the CPython team has compiled Windows installers (MSI packages) with every release for many years. These installers are primarily intended to add together a per-user installation of Python, with the core interpreter and library being used by a single user. The installer is besides able to install for all users of a unmarried car, and a carve up Zippo file is available for awarding-local distributions.

3.1.i. Supported Versions¶

As specified in PEP 11, a Python release but supports a Windows platform while Microsoft considers the platform under extended support. This means that Python 3.vi supports Windows Vista and newer. If you lot require Windows XP support and so please install Python iii.4.

3.1.two. Installation Steps¶

Four Python iii.six installers are available for download - two each for the 32-bit and 64-bit versions of the interpreter. The web installer is a small initial download, and it will automatically download the required components as necessary. The offline installer includes the components necessary for a default installation and only requires an net connectedness for optional features. See Installing Without Downloading for other ways to avoid downloading during installation.

After starting the installer, one of two options may be selected:

../_images/win_installer.png

If you select "Install Now":

  • You volition not need to exist an administrator (unless a system update for the C Runtime Library is required or you install the Python Launcher for Windows for all users)
  • Python will be installed into your user directory
  • The Python Launcher for Windows will exist installed co-ordinate to the option at the bottom of the outset page
  • The standard library, test suite, launcher and pip will exist installed
  • If selected, the install directory volition be added to your PATH
  • Shortcuts will only be visible for the electric current user

Selecting "Customize installation" volition allow you to select the features to install, the installation location and other options or post-install deportment. To install debugging symbols or binaries, you will need to employ this option.

To perform an all-users installation, you should select "Customize installation". In this example:

  • Y'all may exist required to provide administrative credentials or approval
  • Python will be installed into the Program Files directory
  • The Python Launcher for Windows will be installed into the Windows directory
  • Optional features may be selected during installation
  • The standard library can be pre-compiled to bytecode
  • If selected, the install directory will be added to the system PATH
  • Shortcuts are available for all users

3.i.3. Removing the MAX_PATH Limitation¶

Windows historically has limited path lengths to 260 characters. This meant that paths longer than this would not resolve and errors would effect.

In the latest versions of Windows, this limitation can be expanded to approximately 32,000 characters. Your administrator will need to activate the "Enable Win32 long paths" group policy, or gear up the registry value HKEY_LOCAL_MACHINE\Arrangement\CurrentControlSet\Control\FileSystem@LongPathsEnabled to i .

This allows the open up() function, the bone module and most other path functionality to accept and return paths longer than 260 characters when using strings. (Utilise of bytes equally paths is deprecated on Windows, and this characteristic is not available when using bytes.)

Afterwards changing the above option, no further configuration is required.

Changed in version three.6: Back up for long paths was enabled in Python.

iii.1.4. Installing Without UI¶

All of the options available in the installer UI can too exist specified from the command line, allowing scripted installers to replicate an installation on many machines without user interaction. These options may also exist set without suppressing the UI in order to modify some of the defaults.

To completely hide the installer UI and install Python silently, pass the /quiet selection. To skip past the user interaction but still brandish progress and errors, pass the /passive pick. The /uninstall option may exist passed to immediately begin removing Python - no prompt will exist displayed.

All other options are passed equally proper name=value , where the value is commonly 0 to disable a feature, i to enable a feature, or a path. The total list of bachelor options is shown below.

Name Description Default
InstallAllUsers Perform a arrangement-wide installation. 0
TargetDir The installation directory Selected based on InstallAllUsers
DefaultAllUsersTargetDir The default installation directory for all-user installs %ProgramFiles%\Python X.Y or %ProgramFiles(x86)%\Python X.Y
DefaultJustForMeTargetDir The default install directory for just-for-me installs %LocalAppData%\Programs\PythonXY or %LocalAppData%\Programs\PythonXY-32
DefaultCustomTargetDir The default custom install directory displayed in the UI (empty)
AssociateFiles Create file associations if the launcher is besides installed. 1
CompileAll Compile all .py files to .pyc . 0
PrependPath Add install and Scripts directories tho PATH and .PY to PATHEXT 0
Shortcuts Create shortcuts for the interpreter, documentation and IDLE if installed. 1
Include_doc Install Python manual 1
Include_debug Install debug binaries 0
Include_dev Install developer headers and libraries 1
Include_exe Install python.exe and related files i
Include_launcher Install Python Launcher for Windows. ane
InstallLauncherAllUsers Installs Python Launcher for Windows for all users. 1
Include_lib Install standard library and extension modules 1
Include_pip Install bundled pip and setuptools 1
Include_symbols Install debugging symbols (*.pdb) 0
Include_tcltk Install Tcl/Tk support and IDLE 1
Include_test Install standard library test suite 1
Include_tools Install utility scripts 1
LauncherOnly But installs the launcher. This will override almost other options. 0
SimpleInstall Disable most install UI 0
SimpleInstallDescription A custom message to display when the simplified install UI is used. (empty)

For instance, to silently install a default, system-wide Python installation, yous could use the following command (from an elevated command prompt):

                python-three.half dozen.0.exe /quiet InstallAllUsers=1 PrependPath=1 Include_test=0

To allow users to easily install a personal copy of Python without the exam suite, you could provide a shortcut with the following command. This will display a simplified initial page and disallow customization:

                python-3.6.0.exe InstallAllUsers=0 Include_launcher=0 Include_test=0     SimpleInstall=i SimpleInstallDescription="Just for me, no exam suite."

(Note that omitting the launcher also omits file associations, and is but recommended for per-user installs when in that location is also a system-broad installation that included the launcher.)

The options listed above can also be provided in a file named unattend.xml alongside the executable. This file specifies a list of options and values. When a value is provided as an aspect, it will be converted to a number if possible. Values provided as element text are ever left as strings. This example file sets the same options and the previous case:

                <Options>     <Selection Proper noun="InstallAllUsers" Value="no" />     <Option Name="Include_launcher" Value="0" />     <Option Name="Include_test" Value="no" />     <Option Proper noun="SimpleInstall" Value="yeah" />     <Pick Proper name="SimpleInstallDescription">Just for me, no exam suite</Pick> </Options>

iii.1.5. Installing Without Downloading¶

As some features of Python are not included in the initial installer download, selecting those features may require an internet connection. To avert this need, all possible components may be downloaded on-need to create a complete layout that will no longer require an internet connection regardless of the selected features. Note that this download may exist bigger than required, but where a large number of installations are going to be performed it is very useful to accept a locally cached copy.

Execute the post-obit control from Command Prompt to download all possible required files. Remember to substitute python-3.half-dozen.0.exe for the actual name of your installer, and to create layouts in their ain directories to avoid collisions betwixt files with the same proper noun.

                python-three.half-dozen.0.exe /layout [optional target directory]

You lot may also specify the /quiet option to hide the progress display.

3.1.6. Modifying an install¶

Once Python has been installed, y'all tin add or remove features through the Programs and Features tool that is role of Windows. Select the Python entry and cull "Uninstall/Change" to open the installer in maintenance manner.

"Change" allows yous to add or remove features by modifying the checkboxes - unchanged checkboxes will non install or remove anything. Some options cannot exist changed in this fashion, such every bit the install directory; to modify these, you will need to remove and then reinstall Python completely.

"Repair" will verify all the files that should be installed using the current settings and replace whatsoever that accept been removed or modified.

"Uninstall" will remove Python entirely, with the exception of the Python Launcher for Windows, which has its ain entry in Programs and Features.

three.ane.7. Other Platforms¶

With ongoing development of Python, some platforms that used to be supported earlier are no longer supported (due to the lack of users or developers). Check PEP xi for details on all unsupported platforms.

  • Windows CE is still supported.
  • The Cygwin installer offers to install the Python interpreter as well (cf. Cygwin packet source, Maintainer releases)

Encounter Python for Windows for detailed information near platforms with pre-compiled installers.

iii.2. Alternative bundles¶

Besides the standard CPython distribution, there are modified packages including additional functionality. The following is a list of popular versions and their key features:

ActivePython
Installer with multi-platform compatibility, documentation, PyWin32
Anaconda
Popular scientific modules (such equally numpy, scipy and pandas) and the conda bundle managing director.
Canopy
A "comprehensive Python analysis environment" with editors and other development tools.
WinPython
Windows-specific distribution with prebuilt scientific packages and tools for building packages.

Note that these packages may not include the latest versions of Python or other libraries, and are not maintained or supported past the core Python team.

3.three. Configuring Python¶

To run Python conveniently from a command prompt, you might consider changing some default surround variables in Windows. While the installer provides an pick to configure the PATH and PATHEXT variables for you, this is only reliable for a single, system-wide installation. If you regularly use multiple versions of Python, consider using the Python Launcher for Windows.

iii.3.one. Excursus: Setting environment variables¶

Windows allows environment variables to be configured permanently at both the User level and the System level, or temporarily in a command prompt.

To temporarily set environment variables, open Command Prompt and employ the fix command:

                C:\>set up PATH=C:\Program Files\Python 3.half-dozen;%PATH% C:\>prepare PYTHONPATH=%PYTHONPATH%;C:\My_python_lib C:\>python

These changes will employ to whatsoever further commands executed in that console, and will be inherited by any applications started from the console.

Including the variable name within percent signs will aggrandize to the existing value, assuasive you lot to add together your new value at either the start or the cease. Modifying PATH by adding the directory containing python.exe to the commencement is a common way to ensure the right version of Python is launched.

To permanently alter the default environment variables, click Start and search for 'edit surround variables', or open Organization properties, Advanced system settings and click the Environment Variables button. In this dialog, you can add or change User and System variables. To alter System variables, y'all need not-restricted access to your machine (i.due east. Administrator rights).

Note

Windows will concatenate User variables later on System variables, which may cause unexpected results when modifying PATH .

The PYTHONPATH variable is used by all versions of Python two and Python three, so you should non permanently configure this variable unless it just includes lawmaking that is uniform with all of your installed Python versions.

three.3.2. Finding the Python executable¶

Changed in version three.5.

Besides using the automatically created get-go carte entry for the Python interpreter, yous might desire to start Python in the command prompt. The installer has an option to set that up for you.

On the first page of the installer, an option labelled "Add Python to PATH" may be selected to have the installer add the install location into the PATH . The location of the Scripts\ folder is likewise added. This allows you to type python to run the interpreter, and pip for the package installer. Thus, yous can too execute your scripts with command line options, meet Command line documentation.

If you don't enable this choice at install fourth dimension, you tin can always re-run the installer, select Alter, and enable information technology. Alternatively, you can manually modify the PATH using the directions in Excursus: Setting environs variables. Y'all demand to set your PATH environment variable to include the directory of your Python installation, delimited by a semicolon from other entries. An example variable could await like this (assuming the beginning two entries already existed):

                C:\WINDOWS\system32;C:\WINDOWS;C:\Plan Files\Python 3.6

3.4. Python Launcher for Windows¶

New in version iii.3.

The Python launcher for Windows is a utility which aids in locating and executing of different Python versions. It allows scripts (or the command-line) to signal a preference for a specific Python version, and will locate and execute that version.

Dissimilar the PATH variable, the launcher will correctly select the most advisable version of Python. It will adopt per-user installations over organisation-wide ones, and orders by linguistic communication version rather than using the most recently installed version.

3.4.1. Getting started¶

three.iv.1.ane. From the command-line¶

Changed in version 3.6.

System-broad installations of Python iii.3 and after volition put the launcher on your PATH . The launcher is compatible with all available versions of Python, so it does non matter which version is installed. To check that the launcher is bachelor, execute the following control in Control Prompt:

You should find that the latest version of Python you accept installed is started - it can be exited as normal, and any additional command-line arguments specified will exist sent directly to Python.

If yous have multiple versions of Python installed (due east.g., 2.vii and 3.half dozen) y'all volition have noticed that Python three.half-dozen was started - to launch Python 2.7, try the command:

If you want the latest version of Python 2.x you accept installed, endeavour the command:

You should find the latest version of Python 2.x starts.

If you see the following error, y'all exercise not have the launcher installed:

                  'py' is not recognized as an internal or external command, operable program or batch file.

Per-user installations of Python do not add the launcher to PATH unless the choice was selected on installation.

iii.4.ane.ii. Virtual environments¶

New in version iii.5.

If the launcher is run with no explicit Python version specification, and a virtual surroundings (created with the standard library venv module or the external virtualenv tool) agile, the launcher volition run the virtual environment's interpreter rather than the global 1. To run the global interpreter, either conciliate the virtual environment, or explicitly specify the global Python version.

three.4.i.iii. From a script¶

Let'south create a exam Python script - create a file chosen hello.py with the following contents

                  #! python import sys sys.stdout.write("hello from Python %s\n" % (sys.version,))

From the directory in which hello.py lives, execute the control:

You lot should find the version number of your latest Python 2.x installation is printed. At present try changing the first line to be:

Re-executing the command should now print the latest Python 3.10 data. As with the higher up control-line examples, you tin specify a more explicit version qualifier. Assuming you have Python 2.6 installed, try changing the first line to #! python2.6 and you should detect the ii.6 version data printed.

Note that unlike interactive use, a bare "python" volition employ the latest version of Python 2.x that you have installed. This is for backward compatibility and for compatibility with Unix, where the command python typically refers to Python 2.

3.iv.1.4. From file associations¶

The launcher should have been associated with Python files (i.e. .py , .pyw , .pyc files) when information technology was installed. This means that when you double-click on 1 of these files from Windows explorer the launcher volition be used, and therefore you can apply the same facilities described above to have the script specify the version which should be used.

The key do good of this is that a single launcher tin support multiple Python versions at the same fourth dimension depending on the contents of the first line.

3.iv.2. Shebang Lines¶

If the get-go line of a script file starts with #! , it is known as a "shebang" line. Linux and other Unix like operating systems accept native back up for such lines and they are commonly used on such systems to bespeak how a script should be executed. This launcher allows the same facilities to be used with Python scripts on Windows and the examples above demonstrate their utilize.

To let shebang lines in Python scripts to exist portable between Unix and Windows, this launcher supports a number of 'virtual' commands to specify which interpreter to use. The supported virtual commands are:

  • /usr/bin/env python
  • /usr/bin/python
  • /usr/local/bin/python
  • python

For example, if the starting time line of your script starts with

The default Python will be located and used. As many Python scripts written to work on Unix will already have this line, you lot should discover these scripts tin exist used by the launcher without modification. If you are writing a new script on Windows which you lot hope will be useful on Unix, yous should use one of the shebang lines starting with /usr .

Any of the above virtual commands tin exist suffixed with an explicit version (either just the major version, or the major and minor version) - for example /usr/bin/python2.vii - which will cause that specific version to exist located and used.

The /usr/bin/env form of shebang line has one further special belongings. Earlier looking for installed Python interpreters, this form will search the executable PATH for a Python executable. This corresponds to the behaviour of the Unix env program, which performs a PATH search.

3.iv.3. Arguments in shebang lines¶

The shebang lines can too specify additional options to be passed to the Python interpreter. For example, if you accept a shebang line:

Then Python volition exist started with the -v option

3.4.iv. Customization¶

iii.4.4.1. Customization via INI files¶

2 .ini files volition be searched by the launcher - py.ini in the electric current user's "application data" directory (i.e. the directory returned by calling the Windows part SHGetFolderPath with CSIDL_LOCAL_APPDATA) and py.ini in the same directory every bit the launcher. The same .ini files are used for both the 'console' version of the launcher (i.e. py.exe) and for the 'windows' version (i.due east. pyw.exe)

Customization specified in the "application directory" will have precedence over the ane next to the executable, so a user, who may not have write access to the .ini file side by side to the launcher, tin can override commands in that global .ini file)

3.4.4.ii. Customizing default Python versions¶

In some cases, a version qualifier can be included in a control to dictate which version of Python volition exist used past the command. A version qualifier starts with a major version number and can optionally be followed by a flow ('.') and a minor version specifier. If the minor qualifier is specified, it may optionally be followed past "-32" to indicate the 32-bit implementation of that version be used.

For example, a shebang line of #!python has no version qualifier, while #!python3 has a version qualifier which specifies only a major version.

If no version qualifiers are found in a command, the surround variable PY_PYTHON tin be set to specify the default version qualifier - the default value is "2". Note this value could specify just a major version (due east.g. "2") or a major.minor qualifier (e.g. "2.6"), or fifty-fifty major.small-32.

If no minor version qualifiers are institute, the environment variable PY_PYTHON{major} (where {major} is the current major version qualifier as determined above) can exist set to specify the full version. If no such option is establish, the launcher will enumerate the installed Python versions and use the latest small release found for the major version, which is probable, although not guaranteed, to be the most recently installed version in that family.

On 64-bit Windows with both 32-fleck and 64-flake implementations of the aforementioned (major.minor) Python version installed, the 64-bit version volition always be preferred. This will be truthful for both 32-bit and 64-bit implementations of the launcher - a 32-bit launcher will prefer to execute a 64-bit Python installation of the specified version if available. This is so the behavior of the launcher can be predicted knowing only what versions are installed on the PC and without regard to the club in which they were installed (i.e., without knowing whether a 32 or 64-chip version of Python and corresponding launcher was installed last). As noted to a higher place, an optional "-32" suffix can be used on a version specifier to change this behaviour.

Examples:

  • If no relevant options are set up, the commands python and python2 volition use the latest Python 2.x version installed and the control python3 will utilise the latest Python 3.10 installed.
  • The commands python3.i and python2.seven will not consult any options at all as the versions are fully specified.
  • If PY_PYTHON=iii , the commands python and python3 will both use the latest installed Python three version.
  • If PY_PYTHON=3.i-32 , the command python will apply the 32-bit implementation of 3.i whereas the control python3 will use the latest installed Python (PY_PYTHON was not considered at all as a major version was specified.)
  • If PY_PYTHON=3 and PY_PYTHON3=3.1 , the commands python and python3 will both employ specifically 3.1

In addition to surround variables, the same settings can be configured in the .INI file used past the launcher. The section in the INI file is called [defaults] and the fundamental name will be the aforementioned as the surroundings variables without the leading PY_ prefix (and notation that the key names in the INI file are instance insensitive.) The contents of an environment variable will override things specified in the INI file.

For instance:

  • Setting PY_PYTHON=3.1 is equivalent to the INI file containing:
  • Setting PY_PYTHON=3 and PY_PYTHON3=3.1 is equivalent to the INI file containing:
                  [defaults] python=3 python3=three.1

3.four.v. Diagnostics¶

If an environment variable PYLAUNCH_DEBUG is set up (to whatsoever value), the launcher will print diagnostic data to stderr (i.east. to the console). While this information manages to be simultaneously verbose and terse, information technology should let you to see what versions of Python were located, why a item version was called and the verbal command-line used to execute the target Python.

3.5. Finding modules¶

Python commonly stores its library (and thereby your site-packages folder) in the installation directory. So, if you lot had installed Python to C:\Python\ , the default library would reside in C:\Python\Lib\ and third-party modules should be stored in C:\Python\Lib\site-packages\ .

To completely override sys.path , create a ._pth file with the aforementioned proper noun as the DLL ( python36._pth ) or the executable ( python._pth ) and specify i line for each path to add to sys.path . The file based on the DLL name overrides the ane based on the executable, which allows paths to be restricted for any plan loading the runtime if desired.

When the file exists, all registry and environment variables are ignored, isolated mode is enabled, and site is not imported unless i line in the file specifies import site . Blank paths and lines starting with # are ignored. Each path may be absolute or relative to the location of the file. Import statements other than to site are not permitted, and arbitrary lawmaking cannot exist specified.

Notation that .pth files (without leading underscore) volition be processed normally by the site module.

When no ._pth file is found, this is how sys.path is populated on Windows:

  • An empty entry is added at the start, which corresponds to the electric current directory.
  • If the environment variable PYTHONPATH exists, as described in Environment variables, its entries are added next. Note that on Windows, paths in this variable must be separated past semicolons, to distinguish them from the colon used in drive identifiers ( C:\ etc.).
  • Additional "awarding paths" can be added in the registry as subkeys of \SOFTWARE\Python\PythonCore\ version \PythonPath under both the HKEY_CURRENT_USER and HKEY_LOCAL_MACHINE hives. Subkeys which have semicolon-delimited path strings equally their default value volition cause each path to exist added to sys.path . (Annotation that all known installers only use HKLM, so HKCU is typically empty.)
  • If the surround variable PYTHONHOME is prepare, it is assumed as "Python Home". Otherwise, the path of the main Python executable is used to locate a "landmark file" (either Lib\os.py or pythonXY.null ) to deduce the "Python Home". If a Python home is found, the relevant sub-directories added to sys.path ( Lib , plat-win , etc) are based on that binder. Otherwise, the core Python path is synthetic from the PythonPath stored in the registry.
  • If the Python Domicile cannot be located, no PYTHONPATH is specified in the environment, and no registry entries can be found, a default path with relative entries is used (e.g. .\Lib;.\plat-win , etc).

If a pyvenv.cfg file is plant alongside the main executable or in the directory 1 level in a higher place the executable, the post-obit variations utilise:

  • If dwelling house is an absolute path and PYTHONHOME is not fix, this path is used instead of the path to the master executable when deducing the home location.

The terminate result of all this is:

  • When running python.exe , or any other .exe in the chief Python directory (either an installed version, or direct from the PCbuild directory), the core path is deduced, and the cadre paths in the registry are ignored. Other "awarding paths" in the registry are always read.
  • When Python is hosted in another .exe (different directory, embedded via COM, etc), the "Python Home" will not be deduced, then the cadre path from the registry is used. Other "application paths" in the registry are ever read.
  • If Python can't find its habitation and at that place are no registry value (frozen .exe, some very strange installation setup) you lot get a path with some default, simply relative, paths.

For those who want to bundle Python into their application or distribution, the post-obit advice will foreclose conflicts with other installations:

  • Include a ._pth file alongside your executable containing the directories to include. This will ignore paths listed in the registry and environment variables, and also ignore site unless import site is listed.
  • If you lot are loading python3.dll or python36.dll in your ain executable, explicitly call Py_SetPath() or (at least) Py_SetProgramName() earlier Py_Initialize() .
  • Clear and/or overwrite PYTHONPATH and set PYTHONHOME earlier launching python.exe from your application.
  • If y'all cannot use the previous suggestions (for example, you are a distribution that allows people to run python.exe directly), ensure that the landmark file ( Lib\os.py ) exists in your install directory. (Note that information technology will non be detected inside a Naught file, merely a correctly named Goose egg file will exist detected instead.)

These will ensure that the files in a system-wide installation will not take precedence over the copy of the standard library bundled with your awarding. Otherwise, your users may experience issues using your application. Note that the first proposition is the all-time, every bit the other may withal exist susceptible to non-standard paths in the registry and user site-packages.

Changed in version iii.6:

  • Adds ._pth file support and removes applocal option from pyvenv.cfg .
  • Adds pythonXX.zip as a potential landmark when directly next to the executable.

Deprecated since version three.6:

Modules specified in the registry under Modules (not PythonPath ) may be imported by importlib.mechanism.WindowsRegistryFinder . This finder is enabled on Windows in 3.6.0 and earlier, but may need to be explicitly added to sys.meta_path in the futurity.

3.6. Additional modules¶

Even though Python aims to be portable among all platforms, at that place are features that are unique to Windows. A couple of modules, both in the standard library and external, and snippets be to employ these features.

The Windows-specific standard modules are documented in MS Windows Specific Services.

iii.6.1. PyWin32¶

The PyWin32 module by Marker Hammond is a drove of modules for avant-garde Windows-specific support. This includes utilities for:

  • Component Object Model (COM)
  • Win32 API calls
  • Registry
  • Event log
  • Microsoft Foundation Classes (MFC) user interfaces

PythonWin is a sample MFC application shipped with PyWin32. Information technology is an embeddable IDE with a born debugger.

3.6.2. cx_Freeze¶

cx_Freeze is a distutils extension (meet Extending Distutils) which wraps Python scripts into executable Windows programs ( * .exe files). When you have done this, you can distribute your application without requiring your users to install Python.

three.6.3. WConio¶

Since Python'south advanced terminal handling layer, curses , is restricted to Unix-like systems, there is a library exclusive to Windows every bit well: Windows Console I/O for Python.

WConio is a wrapper for Turbo-C's CONIO.H , used to create text user interfaces.

three.vii. Compiling Python on Windows¶

If you want to compile CPython yourself, first thing you should do is get the source. Yous can download either the latest release's source or only catch a fresh checkout.

The source tree contains a build solution and project files for Microsoft Visual Studio 2015, which is the compiler used to build the official Python releases. These files are in the PCbuild directory.

Cheque PCbuild/readme.txt for general data on the build process.

For extension modules, consult Building C and C++ Extensions on Windows.

3.viii. Embedded Distribution¶

New in version 3.v.

The embedded distribution is a ZIP file containing a minimal Python environment. It is intended for acting as role of another application, rather than being direct accessed by end-users.

When extracted, the embedded distribution is (virtually) fully isolated from the user's system, including environment variables, system registry settings, and installed packages. The standard library is included as pre-compiled and optimized .pyc files in a ZIP, and python3.dll , python36.dll , python.exe and pythonw.exe are all provided. Tcl/tk (including all dependants, such every bit Idle), pip and the Python documentation are not included.

Annotation

The embedded distribution does not include the Microsoft C Runtime and it is the responsibility of the application installer to provide this. The runtime may have already been installed on a user'south organization previously or automatically via Windows Update, and tin can be detected by finding ucrtbase.dll in the system directory.

Third-party packages should be installed by the application installer alongside the embedded distribution. Using pip to manage dependencies as for a regular Python installation is not supported with this distribution, though with some care it may be possible to include and use pip for automatic updates. In general, third-party packages should be treated equally office of the application ("vendoring") so that the developer can ensure compatibility with newer versions before providing updates to users.

The two recommended utilize cases for this distribution are described below.

3.eight.ane. Python Application¶

An application written in Python does not necessarily crave users to exist aware of that fact. The embedded distribution may be used in this case to include a private version of Python in an install parcel. Depending on how transparent it should exist (or conversely, how professional it should appear), there are two options.

Using a specialized executable as a launcher requires some coding, but provides the most transparent experience for users. With a customized launcher, there are no obvious indications that the program is running on Python: icons can be customized, company and version data can be specified, and file associations comport properly. In most cases, a custom launcher should simply be able to telephone call Py_Main with a hard-coded control line.

The simpler arroyo is to provide a batch file or generated shortcut that directly calls the python.exe or pythonw.exe with the required command-line arguments. In this instance, the awarding volition appear to be Python and not its actual proper name, and users may have trouble distinguishing it from other running Python processes or file associations.

With the latter arroyo, packages should be installed as directories alongside the Python executable to ensure they are available on the path. With the specialized launcher, packages can be located in other locations as in that location is an opportunity to specify the search path before launching the awarding.

3.viii.2. Embedding Python¶

Applications written in native code often crave some form of scripting linguistic communication, and the embedded Python distribution can be used for this purpose. In full general, the bulk of the application is in native code, and some office will either invoke python.exe or directly apply python3.dll . For either case, extracting the embedded distribution to a subdirectory of the awarding installation is sufficient to provide a loadable Python interpreter.

As with the application use, packages can be installed to any location as there is an opportunity to specify search paths earlier initializing the interpreter. Otherwise, there is no primal differences between using the embedded distribution and a regular installation.

3.9. Other resource¶