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0001 .. _type-conversions:
0002
0003 Type conversions
0004 ################
0005
0006 Apart from enabling cross-language function calls, a fundamental problem
0007 that a binding tool like pybind11 must address is to provide access to
0008 native Python types in C++ and vice versa. There are three fundamentally
0009 different ways to do this—which approach is preferable for a particular type
0010 depends on the situation at hand.
0011
0012 1. Use a native C++ type everywhere. In this case, the type must be wrapped
0013 using pybind11-generated bindings so that Python can interact with it.
0014
0015 2. Use a native Python type everywhere. It will need to be wrapped so that
0016 C++ functions can interact with it.
0017
0018 3. Use a native C++ type on the C++ side and a native Python type on the
0019 Python side. pybind11 refers to this as a *type conversion*.
0020
0021 Type conversions are the most "natural" option in the sense that native
0022 (non-wrapped) types are used everywhere. The main downside is that a copy
0023 of the data must be made on every Python ↔ C++ transition: this is
0024 needed since the C++ and Python versions of the same type generally won't
0025 have the same memory layout.
0026
0027 pybind11 can perform many kinds of conversions automatically. An overview
0028 is provided in the table ":ref:`conversion_table`".
0029
0030 The following subsections discuss the differences between these options in more
0031 detail. The main focus in this section is on type conversions, which represent
0032 the last case of the above list.
0033
0034 .. toctree::
0035 :maxdepth: 1
0036
0037 overview
0038 strings
0039 stl
0040 functional
0041 chrono
0042 eigen
0043 custom
