Quick Start Guide ----------------- 1. Install Microsoft Visual Studio 2017 or later with Python workload and Python native development component. 1a. Optionally install Python 3.6 or later. If not installed, get_externals.bat (via build.bat) will download and use Python via NuGet. 2. Run "build.bat" to build Python in 32-bit Release configuration. 3. (Optional, but recommended) Run the test suite with "rt.bat -q". Building Python using Microsoft Visual C++ ------------------------------------------ This directory is used to build CPython for Microsoft Windows on 32- and 64- bit platforms. Using this directory requires an installation of Microsoft Visual Studio (MSVC) with the *Python workload* and its optional *Python native development* component selected. Building from the command line is recommended in order to obtain any external dependencies. To build, simply run the "build.bat" script without any arguments. After this succeeds, you can open the "pcbuild.sln" solution in Visual Studio to continue development. To build an installer package, refer to the README in the Tools/msi folder. The solution currently supports two platforms. The Win32 platform is used to build standard x86-compatible 32-bit binaries, output into the win32 sub-directory. The x64 platform is used for building 64-bit AMD64 (aka x86_64 or EM64T) binaries, output into the amd64 sub-directory. The Itanium (IA-64) platform is no longer supported. Four configuration options are supported by the solution: Debug Used to build Python with extra debugging capabilities, equivalent to using ./configure --with-pydebug on UNIX. All binaries built using this configuration have "_d" added to their name: python310_d.dll, python_d.exe, parser_d.pyd, and so on. Both the build and rt (run test) batch files in this directory accept a -d option for debug builds. If you are building Python to help with development of CPython, you will most likely use this configuration. PGInstrument, PGUpdate Used to build Python in Release configuration using PGO, which requires Premium Edition of Visual Studio. See the "Profile Guided Optimization" section below for more information. Build output from each of these configurations lands in its own sub-directory of this directory. The official Python releases may be built using these configurations. Release Used to build Python as it is meant to be used in production settings, though without PGO. Building Python using the build.bat script ---------------------------------------------- In this directory you can find build.bat, a script designed to make building Python on Windows simpler. This script will use the env.bat script to detect either Visual Studio 2017 or 2015, either of which may be used to build Python. Currently Visual Studio 2017 is officially supported. By default, build.bat will build Python in Release configuration for the 32-bit Win32 platform. It accepts several arguments to change this behavior, try `build.bat -h` to learn more. C Runtime --------- Visual Studio 2017 uses version 14.0 of the C runtime (vcruntime140). The executables no longer use the "Side by Side" assemblies used in previous versions of the compiler. This simplifies distribution of applications. The run time libraries are available under the redist folder of your Visual Studio distribution. For more info, see the Readme in the redist folder. Sub-Projects ------------ The CPython project is split up into several smaller sub-projects which are managed by the pcbuild.sln solution file. Each sub-project is represented by a .vcxproj and a .vcxproj.filters file starting with the name of the sub-project. These sub-projects fall into a few general categories: The following sub-projects represent the bare minimum required to build a functioning CPython interpreter. If nothing else builds but these, you'll have a very limited but usable python.exe: pythoncore .dll and .lib python .exe These sub-projects provide extra executables that are useful for running CPython in different ways: pythonw pythonw.exe, a variant of python.exe that doesn't open a Command Prompt window pylauncher py.exe, the Python Launcher for Windows, see https://docs.python.org/3/using/windows.html#launcher pywlauncher pyw.exe, a variant of py.exe that doesn't open a Command Prompt window _testembed _testembed.exe, a small program that embeds Python for testing purposes, used by test_capi.py These are miscellaneous sub-projects that don't really fit the other categories: _freeze_module _freeze_module.exe, used to regenerate frozen modules in Python after changes have been made to the corresponding source files (e.g. Lib\importlib\_bootstrap.py). pyshellext pyshellext.dll, the shell extension deployed with the launcher python3dll python3.dll, the PEP 384 Stable ABI dll xxlimited builds an example module that makes use of the PEP 384 Stable ABI, see Modules\xxlimited.c xxlimited_35 ditto for testing the Python 3.5 stable ABI, see Modules\xxlimited_35.c The following sub-projects are for individual modules of the standard library which are implemented in C; each one builds a DLL (renamed to .pyd) of the same name as the project: _asyncio _ctypes _ctypes_test _zoneinfo _decimal _elementtree _hashlib _multiprocessing _overlapped _socket _testbuffer _testcapi _testclinic _testclinic_limited _testconsole _testimportmultiple _testmultiphase _testsinglephase _tkinter pyexpat select unicodedata winsound The following Python-controlled sub-projects wrap external projects. Note that these external libraries are not necessary for a working interpreter, but they do implement several major features. See the "Getting External Sources" section below for additional information about getting the source for building these libraries. The sub-projects are: _bz2 Python wrapper for version 1.0.8 of the libbzip2 compression library Homepage: http://www.bzip.org/ _lzma Python wrapper for version 5.2.2 of the liblzma compression library Homepage: https://tukaani.org/xz/ _ssl Python wrapper for version 3.0 of the OpenSSL secure sockets library, which is downloaded from our binaries repository at https://github.com/python/cpython-bin-deps. Homepage: https://www.openssl.org/ Building OpenSSL requires Perl on your path, and can be performed by running PCbuild\prepare_ssl.bat. This will retrieve the version of the sources matched to the current commit from the OpenSSL branch in our source repository at https://github.com/python/cpython-source-deps. To use an alternative build of OpenSSL completely, you should replace the files in the externals/openssl-bin- folder with your own. As long as this folder exists, its contents will not be downloaded again when building. _sqlite3 Wraps SQLite 3.42.0, which is itself built by sqlite3.vcxproj Homepage: https://www.sqlite.org/ _tkinter Wraps version 8.6.6 of the Tk windowing system, which is downloaded from our binaries repository at https://github.com/python/cpython-bin-deps. Homepage: https://www.tcl.tk/ Building Tcl and Tk can be performed by running PCbuild\prepare_tcltk.bat. This will retrieve the version of the sources matched to the current commit from the Tcl and Tk branches in our source repository at https://github.com/python/cpython-source-deps. The two projects install their respective components in a directory alongside the source directories called "tcltk" on Win32 and "tcltk64" on x64. They also copy the Tcl and Tk DLLs into the current output directory, which should ensure that Tkinter is able to load Tcl/Tk without having to change your PATH. Getting External Sources ------------------------ The last category of sub-projects listed above wrap external projects Python doesn't control, and as such a little more work is required in order to download the relevant source files for each project before they can be built. However, a simple script is provided to make this as painless as possible, called "get_externals.bat" and located in this directory. This script extracts all the external sub-projects from https://github.com/python/cpython-source-deps and https://github.com/python/cpython-bin-deps via a Python script called "get_external.py", located in this directory. If Python 3.6 or later is not available via the "py.exe" launcher, the path or command to use for Python can be provided in the PYTHON_FOR_BUILD environment variable, or get_externals.bat will download the latest version of NuGet and use it to download the latest "pythonx86" package for use with get_external.py. Everything downloaded by these scripts is stored in ..\externals (relative to this directory). It is also possible to download sources from each project's homepage, though you may have to change folder names or pass the names to MSBuild as the values of certain properties in order for the build solution to find them. This is an advanced topic and not necessarily fully supported. The get_externals.bat script is called automatically by build.bat unless you pass the '-E' option. Profile Guided Optimization --------------------------- The solution has two configurations for PGO. The PGInstrument configuration must be built first. The PGInstrument binaries are linked against a profiling library and contain extra debug information. The PGUpdate configuration takes the profiling data and generates optimized binaries. The build.bat script has an argument `--pgo` that automate the creation of optimized binaries. It creates the PGI files, runs the unit test suite with the PGI python, and finally creates the optimized files. You can customize the job for profiling with `--pgo-job ` option. See https://docs.microsoft.com/en-us/cpp/build/profile-guided-optimizations for more on this topic. Static library -------------- The solution has no configuration for static libraries. However it is easy to build a static library instead of a DLL. You simply have to set the "Configuration Type" to "Static Library (.lib)" and alter the preprocessor macro "Py_ENABLE_SHARED" to "Py_NO_ENABLE_SHARED". You may also have to change the "Runtime Library" from "Multi-threaded DLL (/MD)" to "Multi-threaded (/MT)". Visual Studio properties ------------------------ The PCbuild solution makes use of Visual Studio property files (*.props) to simplify each project. The properties can be viewed in the Property Manager (View -> Other Windows -> Property Manager) but should be carefully modified by hand. The property files used are: * python (versions, directories and build names) * pyproject (base settings for all projects) * openssl (used by projects dependent upon OpenSSL) * tcltk (used by _tkinter, tcl, and tk projects) The pyproject property file defines all of the build settings for each project, with some projects overriding certain specific values. The GUI doesn't always reflect the correct settings and may confuse the user with false information, especially for settings that automatically adapt for different configurations.