1 2 3# pybind11 — Seamless operability between C++11 and Python 4 5[](http://pybind11.readthedocs.org/en/master/?badge=master) 6[](http://pybind11.readthedocs.org/en/stable/?badge=stable) 7[](https://gitter.im/pybind/Lobby) 8[](https://travis-ci.org/pybind/pybind11) 9[](https://ci.appveyor.com/project/wjakob/pybind11) 10 11**pybind11** is a lightweight header-only library that exposes C++ types in Python 12and vice versa, mainly to create Python bindings of existing C++ code. Its 13goals and syntax are similar to the excellent 14[Boost.Python](http://www.boost.org/doc/libs/1_58_0/libs/python/doc/) library 15by David Abrahams: to minimize boilerplate code in traditional extension 16modules by inferring type information using compile-time introspection. 17 18The main issue with Boost.Python—and the reason for creating such a similar 19project—is Boost. Boost is an enormously large and complex suite of utility 20libraries that works with almost every C++ compiler in existence. This 21compatibility has its cost: arcane template tricks and workarounds are 22necessary to support the oldest and buggiest of compiler specimens. Now that 23C++11-compatible compilers are widely available, this heavy machinery has 24become an excessively large and unnecessary dependency. 25 26Think of this library as a tiny self-contained version of Boost.Python with 27everything stripped away that isn't relevant for binding generation. Without 28comments, the core header files only require ~4K lines of code and depend on 29Python (2.7 or 3.x, or PyPy2.7 >= 5.7) and the C++ standard library. This 30compact implementation was possible thanks to some of the new C++11 language 31features (specifically: tuples, lambda functions and variadic templates). Since 32its creation, this library has grown beyond Boost.Python in many ways, leading 33to dramatically simpler binding code in many common situations. 34 35Tutorial and reference documentation is provided at 36[http://pybind11.readthedocs.org/en/master](http://pybind11.readthedocs.org/en/master). 37A PDF version of the manual is available 38[here](https://media.readthedocs.org/pdf/pybind11/master/pybind11.pdf). 39 40## Core features 41pybind11 can map the following core C++ features to Python 42 43- Functions accepting and returning custom data structures per value, reference, or pointer 44- Instance methods and static methods 45- Overloaded functions 46- Instance attributes and static attributes 47- Arbitrary exception types 48- Enumerations 49- Callbacks 50- Iterators and ranges 51- Custom operators 52- Single and multiple inheritance 53- STL data structures 54- Smart pointers with reference counting like ``std::shared_ptr`` 55- Internal references with correct reference counting 56- C++ classes with virtual (and pure virtual) methods can be extended in Python 57 58## Goodies 59In addition to the core functionality, pybind11 provides some extra goodies: 60 61- Python 2.7, 3.x, and PyPy (PyPy2.7 >= 5.7) are supported with an 62 implementation-agnostic interface. 63 64- It is possible to bind C++11 lambda functions with captured variables. The 65 lambda capture data is stored inside the resulting Python function object. 66 67- pybind11 uses C++11 move constructors and move assignment operators whenever 68 possible to efficiently transfer custom data types. 69 70- It's easy to expose the internal storage of custom data types through 71 Pythons' buffer protocols. This is handy e.g. for fast conversion between 72 C++ matrix classes like Eigen and NumPy without expensive copy operations. 73 74- pybind11 can automatically vectorize functions so that they are transparently 75 applied to all entries of one or more NumPy array arguments. 76 77- Python's slice-based access and assignment operations can be supported with 78 just a few lines of code. 79 80- Everything is contained in just a few header files; there is no need to link 81 against any additional libraries. 82 83- Binaries are generally smaller by a factor of at least 2 compared to 84 equivalent bindings generated by Boost.Python. A recent pybind11 conversion 85 of PyRosetta, an enormous Boost.Python binding project, 86 [reported](http://graylab.jhu.edu/RosettaCon2016/PyRosetta-4.pdf) a binary 87 size reduction of **5.4x** and compile time reduction by **5.8x**. 88 89- Function signatures are precomputed at compile time (using ``constexpr``), 90 leading to smaller binaries. 91 92- With little extra effort, C++ types can be pickled and unpickled similar to 93 regular Python objects. 94 95## Supported compilers 96 971. Clang/LLVM 3.3 or newer (for Apple Xcode's clang, this is 5.0.0 or newer) 982. GCC 4.8 or newer 993. Microsoft Visual Studio 2015 Update 3 or newer 1004. Intel C++ compiler 17 or newer (16 with pybind11 v2.0 and 15 with pybind11 v2.0 and a [workaround](https://github.com/pybind/pybind11/issues/276)) 1015. Cygwin/GCC (tested on 2.5.1) 102 103## About 104 105This project was created by [Wenzel Jakob](http://rgl.epfl.ch/people/wjakob). 106Significant features and/or improvements to the code were contributed by 107Jonas Adler, 108Lori A. Burns, 109Sylvain Corlay, 110Trent Houliston, 111Axel Huebl, 112@hulucc, 113Sergey Lyskov 114Johan Mabille, 115Tomasz Miąsko, 116Dean Moldovan, 117Ben Pritchard, 118Jason Rhinelander, 119Boris Schäling, 120Pim Schellart, 121Henry Schreiner, 122Ivan Smirnov, and 123Patrick Stewart. 124 125### License 126 127pybind11 is provided under a BSD-style license that can be found in the 128``LICENSE`` file. By using, distributing, or contributing to this project, 129you agree to the terms and conditions of this license. 130
