Function handle

include/pybind11/pytypes.h:247–247

The default constructor creates a handle with a ``nullptr``-valued pointer

public:
    /// The default constructor creates a handle with a ``nullptr``-valued pointer
    handle() = default;

    /// Enable implicit conversion from ``PyObject *`` and ``nullptr``.
    /// Not using ``handle(PyObject *ptr)`` to avoid implicit conversion from ``0``.