C++ Support¶

autopxd2 supports C++ headers through the libclang backend.

Important

C++ support requires the libclang backend. The default pycparser backend only supports C99.

Basic C++ Usage¶

# Use libclang for C++ headers
autopxd --backend libclang myclass.hpp > myclass.pxd

Or with Docker:

docker run --rm -v $(pwd):/work -w /work ghcr.io/elijahr/python-autopxd2 autopxd myclass.hpp

Supported C++ Features¶

Classes¶

C++ classes are converted to Cython structs:

// widget.hpp
class Widget {
public:
    int width;
    int height;
};

Generates:

cdef extern from "widget.hpp":

    cdef struct Widget:
        int width
        int height

Structs¶

C++ structs work the same as C:

struct Point {
    double x;
    double y;
};

Functions¶

Global functions are converted directly:

double distance(const Point& a, const Point& b);

Generates:

double distance(const Point & a, const Point & b)

Namespaces¶

Currently, only top-level declarations are extracted. Namespaced declarations are not directly supported.

Limitations¶

Methods¶

Class methods are not included in the generated .pxd. Only public data members are extracted.

For full method support, you'll need to manually add method declarations or use Cython's cppclass syntax.

Templates¶

Template classes are supported through the libclang backend, including primary templates and full specializations. See C++ Template Support for details.

Overloading¶

Multiple overloaded functions with the same name may produce conflicts. You may need to manually select which overload to use.

Best Practices¶

Use header-only libraries where possible for simpler integration
Start with the Docker image to avoid libclang installation issues
Check generated output and manually adjust for complex C++ features
Consider Cython's cppclass for classes with methods you need to call

Example Workflow¶

Generate initial pxd:

autopxd --backend libclang mylib.hpp > mylib.pxd

Review and adjust for methods, templates, or other features

Create your Cython wrapper:

# mylib.pyx
from mylib cimport Widget

def create_widget(width: int, height: int):
    cdef Widget w
    w.width = width
    w.height = height
    return (w.width, w.height)