README.md
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
