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+Overview
+########
+
+.. rubric:: 1. Native type in C++, wrapper in Python
+
+Exposing a custom C++ type using :class:`py::class_` was covered in detail
+in the :doc:`/classes` section. There, the underlying data structure is
+always the original C++ class while the :class:`py::class_` wrapper provides
+a Python interface. Internally, when an object like this is sent from C++ to
+Python, pybind11 will just add the outer wrapper layer over the native C++
+object. Getting it back from Python is just a matter of peeling off the
+wrapper.
+
+.. rubric:: 2. Wrapper in C++, native type in Python
+
+This is the exact opposite situation. Now, we have a type which is native to
+Python, like a ``tuple`` or a ``list``. One way to get this data into C++ is
+with the :class:`py::object` family of wrappers. These are explained in more
+detail in the :doc:`/advanced/pycpp/object` section. We'll just give a quick
+example here:
+
+.. code-block:: cpp
+
+ void print_list(py::list my_list) {
+ for (auto item : my_list)
+ std::cout << item << " ";
+ }
+
+.. code-block:: pycon
+
+ >>> print_list([1, 2, 3])
+ 1 2 3
+
+The Python ``list`` is not converted in any way -- it's just wrapped in a C++
+:class:`py::list` class. At its core it's still a Python object. Copying a
+:class:`py::list` will do the usual reference-counting like in Python.
+Returning the object to Python will just remove the thin wrapper.
+
+.. rubric:: 3. Converting between native C++ and Python types
+
+In the previous two cases we had a native type in one language and a wrapper in
+the other. Now, we have native types on both sides and we convert between them.
+
+.. code-block:: cpp
+
+ void print_vector(const std::vector<int> &v) {
+ for (auto item : v)
+ std::cout << item << "\n";
+ }
+
+.. code-block:: pycon
+
+ >>> print_vector([1, 2, 3])
+ 1 2 3
+
+In this case, pybind11 will construct a new ``std::vector<int>`` and copy each
+element from the Python ``list``. The newly constructed object will be passed
+to ``print_vector``. The same thing happens in the other direction: a new
+``list`` is made to match the value returned from C++.
+
+Lots of these conversions are supported out of the box, as shown in the table
+below. They are very convenient, but keep in mind that these conversions are
+fundamentally based on copying data. This is perfectly fine for small immutable
+types but it may become quite expensive for large data structures. This can be
+avoided by overriding the automatic conversion with a custom wrapper (i.e. the
+above-mentioned approach 1). This requires some manual effort and more details
+are available in the :ref:`opaque` section.
+
+.. _conversion_table:
+
+List of all builtin conversions
+-------------------------------
+
+The following basic data types are supported out of the box (some may require
+an additional extension header to be included). To pass other data structures
+as arguments and return values, refer to the section on binding :ref:`classes`.
+
++---------------------------------+--------------------------+-------------------------------+
+| Data type | Description | Header file |
++=================================+==========================+===============================+
+| ``int8_t``, ``uint8_t`` | 8-bit integers | :file:`pybind11/pybind11.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``int16_t``, ``uint16_t`` | 16-bit integers | :file:`pybind11/pybind11.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``int32_t``, ``uint32_t`` | 32-bit integers | :file:`pybind11/pybind11.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``int64_t``, ``uint64_t`` | 64-bit integers | :file:`pybind11/pybind11.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``ssize_t``, ``size_t`` | Platform-dependent size | :file:`pybind11/pybind11.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``float``, ``double`` | Floating point types | :file:`pybind11/pybind11.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``bool`` | Two-state Boolean type | :file:`pybind11/pybind11.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``char`` | Character literal | :file:`pybind11/pybind11.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``wchar_t`` | Wide character literal | :file:`pybind11/pybind11.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``const char *`` | UTF-8 string literal | :file:`pybind11/pybind11.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``const wchar_t *`` | Wide string literal | :file:`pybind11/pybind11.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``std::string`` | STL dynamic UTF-8 string | :file:`pybind11/pybind11.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``std::wstring`` | STL dynamic wide string | :file:`pybind11/pybind11.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``std::pair<T1, T2>`` | Pair of two custom types | :file:`pybind11/pybind11.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``std::tuple<...>`` | Arbitrary tuple of types | :file:`pybind11/pybind11.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``std::reference_wrapper<...>`` | Reference type wrapper | :file:`pybind11/pybind11.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``std::complex<T>`` | Complex numbers | :file:`pybind11/complex.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``std::array<T, Size>`` | STL static array | :file:`pybind11/stl.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``std::vector<T>`` | STL dynamic array | :file:`pybind11/stl.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``std::list<T>`` | STL linked list | :file:`pybind11/stl.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``std::map<T1, T2>`` | STL ordered map | :file:`pybind11/stl.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``std::unordered_map<T1, T2>`` | STL unordered map | :file:`pybind11/stl.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``std::set<T>`` | STL ordered set | :file:`pybind11/stl.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``std::unordered_set<T>`` | STL unordered set | :file:`pybind11/stl.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``std::function<...>`` | STL polymorphic function | :file:`pybind11/functional.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``std::chrono::duration<...>`` | STL time duration | :file:`pybind11/chrono.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``std::chrono::time_point<...>``| STL date/time | :file:`pybind11/chrono.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``Eigen::Matrix<...>`` | Eigen: dense matrix | :file:`pybind11/eigen.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``Eigen::Map<...>`` | Eigen: mapped memory | :file:`pybind11/eigen.h` |
++---------------------------------+--------------------------+-------------------------------+
+| ``Eigen::SparseMatrix<...>`` | Eigen: sparse matrix | :file:`pybind11/eigen.h` |
++---------------------------------+--------------------------+-------------------------------+