README.md revision 11986
111986Sandreas.sandberg@arm.com 211986Sandreas.sandberg@arm.com 311986Sandreas.sandberg@arm.com# pybind11 — Seamless operability between C++11 and Python 411986Sandreas.sandberg@arm.com 511986Sandreas.sandberg@arm.com[](http://pybind11.readthedocs.org/en/master/?badge=master) 611986Sandreas.sandberg@arm.com[](http://pybind11.readthedocs.org/en/stable/?badge=stable) 711986Sandreas.sandberg@arm.com[](https://travis-ci.org/pybind/pybind11) 811986Sandreas.sandberg@arm.com[](https://ci.appveyor.com/project/wjakob/pybind11) 911986Sandreas.sandberg@arm.com 1011986Sandreas.sandberg@arm.com**pybind11** is a lightweight header-only library that exposes C++ types in Python 1111986Sandreas.sandberg@arm.comand vice versa, mainly to create Python bindings of existing C++ code. Its 1211986Sandreas.sandberg@arm.comgoals and syntax are similar to the excellent 1311986Sandreas.sandberg@arm.com[Boost.Python](http://www.boost.org/doc/libs/1_58_0/libs/python/doc/) library 1411986Sandreas.sandberg@arm.comby David Abrahams: to minimize boilerplate code in traditional extension 1511986Sandreas.sandberg@arm.commodules by inferring type information using compile-time introspection. 1611986Sandreas.sandberg@arm.com 1711986Sandreas.sandberg@arm.comThe main issue with Boost.Python—and the reason for creating such a similar 1811986Sandreas.sandberg@arm.comproject—is Boost. Boost is an enormously large and complex suite of utility 1911986Sandreas.sandberg@arm.comlibraries that works with almost every C++ compiler in existence. This 2011986Sandreas.sandberg@arm.comcompatibility has its cost: arcane template tricks and workarounds are 2111986Sandreas.sandberg@arm.comnecessary to support the oldest and buggiest of compiler specimens. Now that 2211986Sandreas.sandberg@arm.comC++11-compatible compilers are widely available, this heavy machinery has 2311986Sandreas.sandberg@arm.combecome an excessively large and unnecessary dependency. 2411986Sandreas.sandberg@arm.com 2511986Sandreas.sandberg@arm.comThink of this library as a tiny self-contained version of Boost.Python with 2611986Sandreas.sandberg@arm.comeverything stripped away that isn't relevant for binding generation. Without 2711986Sandreas.sandberg@arm.comcomments, the core header files only require ~2.5K lines of code and depend on 2811986Sandreas.sandberg@arm.comPython (2.7 or 3.x) and the C++ standard library. This compact implementation 2911986Sandreas.sandberg@arm.comwas possible thanks to some of the new C++11 language features (specifically: 3011986Sandreas.sandberg@arm.comtuples, lambda functions and variadic templates). Since its creation, this 3111986Sandreas.sandberg@arm.comlibrary has grown beyond Boost.Python in many ways, leading to dramatically 3211986Sandreas.sandberg@arm.comsimpler binding code in many common situations. 3311986Sandreas.sandberg@arm.com 3411986Sandreas.sandberg@arm.comTutorial and reference documentation is provided at 3511986Sandreas.sandberg@arm.com[http://pybind11.readthedocs.org/en/master](http://pybind11.readthedocs.org/en/master). 3611986Sandreas.sandberg@arm.comA PDF version of the manual is available 3711986Sandreas.sandberg@arm.com[here](https://media.readthedocs.org/pdf/pybind11/master/pybind11.pdf). 3811986Sandreas.sandberg@arm.com 3911986Sandreas.sandberg@arm.com## Core features 4011986Sandreas.sandberg@arm.compybind11 can map the following core C++ features to Python 4111986Sandreas.sandberg@arm.com 4211986Sandreas.sandberg@arm.com- Functions accepting and returning custom data structures per value, reference, or pointer 4311986Sandreas.sandberg@arm.com- Instance methods and static methods 4411986Sandreas.sandberg@arm.com- Overloaded functions 4511986Sandreas.sandberg@arm.com- Instance attributes and static attributes 4611986Sandreas.sandberg@arm.com- Arbitrary exception types 4711986Sandreas.sandberg@arm.com- Enumerations 4811986Sandreas.sandberg@arm.com- Callbacks 4911986Sandreas.sandberg@arm.com- Iterators and ranges 5011986Sandreas.sandberg@arm.com- Custom operators 5111986Sandreas.sandberg@arm.com- Single and multiple inheritance 5211986Sandreas.sandberg@arm.com- STL data structures 5311986Sandreas.sandberg@arm.com- Iterators and ranges 5411986Sandreas.sandberg@arm.com- Smart pointers with reference counting like ``std::shared_ptr`` 5511986Sandreas.sandberg@arm.com- Internal references with correct reference counting 5611986Sandreas.sandberg@arm.com- C++ classes with virtual (and pure virtual) methods can be extended in Python 5711986Sandreas.sandberg@arm.com 5811986Sandreas.sandberg@arm.com## Goodies 5911986Sandreas.sandberg@arm.comIn addition to the core functionality, pybind11 provides some extra goodies: 6011986Sandreas.sandberg@arm.com 6111986Sandreas.sandberg@arm.com- pybind11 uses C++11 move constructors and move assignment operators whenever 6211986Sandreas.sandberg@arm.com possible to efficiently transfer custom data types. 6311986Sandreas.sandberg@arm.com 6411986Sandreas.sandberg@arm.com- It is possible to bind C++11 lambda functions with captured variables. The 6511986Sandreas.sandberg@arm.com lambda capture data is stored inside the resulting Python function object. 6611986Sandreas.sandberg@arm.com 6711986Sandreas.sandberg@arm.com- It's easy to expose the internal storage of custom data types through 6811986Sandreas.sandberg@arm.com Pythons' buffer protocols. This is handy e.g. for fast conversion between 6911986Sandreas.sandberg@arm.com C++ matrix classes like Eigen and NumPy without expensive copy operations. 7011986Sandreas.sandberg@arm.com 7111986Sandreas.sandberg@arm.com- pybind11 can automatically vectorize functions so that they are transparently 7211986Sandreas.sandberg@arm.com applied to all entries of one or more NumPy array arguments. 7311986Sandreas.sandberg@arm.com 7411986Sandreas.sandberg@arm.com- Python's slice-based access and assignment operations can be supported with 7511986Sandreas.sandberg@arm.com just a few lines of code. 7611986Sandreas.sandberg@arm.com 7711986Sandreas.sandberg@arm.com- Everything is contained in just a few header files; there is no need to link 7811986Sandreas.sandberg@arm.com against any additional libraries. 7911986Sandreas.sandberg@arm.com 8011986Sandreas.sandberg@arm.com- Binaries are generally smaller by a factor of at least 2 compared to 8111986Sandreas.sandberg@arm.com equivalent bindings generated by Boost.Python. A recent pybind11 conversion 8211986Sandreas.sandberg@arm.com of PyRosetta, an enormous Boost.Python binding project, 8311986Sandreas.sandberg@arm.com [reported](http://graylab.jhu.edu/RosettaCon2016/PyRosetta-4.pdf) a binary 8411986Sandreas.sandberg@arm.com size reduction of **5.4x** and compile time reduction by **5.8x**. 8511986Sandreas.sandberg@arm.com 8611986Sandreas.sandberg@arm.com- When supported by the compiler, two new C++14 features (relaxed constexpr and 8711986Sandreas.sandberg@arm.com return value deduction) are used to precompute function signatures at compile 8811986Sandreas.sandberg@arm.com time, leading to smaller binaries. 8911986Sandreas.sandberg@arm.com 9011986Sandreas.sandberg@arm.com- With little extra effort, C++ types can be pickled and unpickled similar to 9111986Sandreas.sandberg@arm.com regular Python objects. 9211986Sandreas.sandberg@arm.com 9311986Sandreas.sandberg@arm.com## Supported compilers 9411986Sandreas.sandberg@arm.com 9511986Sandreas.sandberg@arm.com1. Clang/LLVM (any non-ancient version with C++11 support) 9611986Sandreas.sandberg@arm.com2. GCC (any non-ancient version with C++11 support) 9711986Sandreas.sandberg@arm.com3. Microsoft Visual Studio 2015 or newer 9811986Sandreas.sandberg@arm.com4. Intel C++ compiler 16 or newer (15 with a [workaround](https://github.com/pybind/pybind11/issues/276)) 9911986Sandreas.sandberg@arm.com5. Cygwin/GCC (tested on 2.5.1) 10011986Sandreas.sandberg@arm.com 10111986Sandreas.sandberg@arm.com## About 10211986Sandreas.sandberg@arm.com 10311986Sandreas.sandberg@arm.comThis project was created by [Wenzel Jakob](https://www.mitsuba-renderer.org/~wenzel/). 10411986Sandreas.sandberg@arm.comSignificant features and/or improvements to the code were contributed by 10511986Sandreas.sandberg@arm.comJonas Adler, 10611986Sandreas.sandberg@arm.comSylvain Corlay, 10711986Sandreas.sandberg@arm.comTrent Houliston, 10811986Sandreas.sandberg@arm.comAxel Huebl, 10911986Sandreas.sandberg@arm.com@hulucc, 11011986Sandreas.sandberg@arm.comSergey Lyskov 11111986Sandreas.sandberg@arm.comJohan Mabille, 11211986Sandreas.sandberg@arm.comTomasz Miąsko, 11311986Sandreas.sandberg@arm.comDean Moldovan, 11411986Sandreas.sandberg@arm.comBen Pritchard, 11511986Sandreas.sandberg@arm.comJason Rhinelander, 11611986Sandreas.sandberg@arm.comBoris Schäling, 11711986Sandreas.sandberg@arm.comPim Schellart, and 11811986Sandreas.sandberg@arm.comIvan Smirnov. 11911986Sandreas.sandberg@arm.com 12011986Sandreas.sandberg@arm.com### License 12111986Sandreas.sandberg@arm.com 12211986Sandreas.sandberg@arm.compybind11 is provided under a BSD-style license that can be found in the 12311986Sandreas.sandberg@arm.com``LICENSE`` file. By using, distributing, or contributing to this project, 12411986Sandreas.sandberg@arm.comyou agree to the terms and conditions of this license. 125
