Please forgive me if this question has been answered but I've searched for days now and cannot find it. How do I expose a c++ struct with a bit field to python using boost::python? When I try I get this error. error: invalid pointer to bit-field ‘frameHdr_s::hdrSize’ Here is the struct: #define DATA_SIZE 0x100 typedef struct frameHdr_s { #define USE_BIT_FIELDS #ifdef USE_BIT_FIELDS // Longword 0 uint32_t hdrSize : 16; ///< Size of the header uint32_t revMin : 8; ///< Frame Minor Version uint32_t revMaj : 8; ///< Frame Major Version #else // Longword 0 uint32_t hdrSize; ///< Size of the header uint32_t revMin ; ///< Frame Minor Version uint32_t revMaj ; ///< Frame Major Version #endif } frameHdr_t; typedef struct frame_t { frameHdr_t frame_header; ///< frame header uint8_t data[DATA_SIZE]; ///< Byte array of data } frame_t; Here is boost code to expose it: using namespace boost::python; BOOST_PYTHON_MODULE(api) { class_<frameHdr_t>("frameHdr_t") .def_readwrite("hdrSize", &frameHdr_t::hdrSize) ; class_<frame_t>("frame_t") .def_readwrite("frame_header", &frame_t::frame_header) ; class_<myClass>("myClass") .def("register_callback", &myClass::register_callback) .def("boo", &myClass::boo) .def("crap", &myClass::crap) ; } I know that with ctypes I can create the same struct as in c++: from ctypes import * class frameHdr_t(Structure): _pack_ = 1 _fields_=[ # Longword 0 ("hdrSize",c_uint32, 16), ("revMin",c_uint32, 8), ("revMaj",c_uint32, 8), ] DATA_SIZE = 0x100 class frame_t(Structure): _pack_ = 1 _fields_=[ ("frame_header",frameHdr_t), ("data",c_uint8 * DATA_SIZE), ] But how do I translate from the Python version of frame_t to the c++ version of frame_t? In summary, * How do I tell boost to expose a bitfield? * If that is not possible, how do I translate from Python frame_t to C++ frame_t using boot? (I don't want to wrap in C because I need to preserve the C++ness of the interface.) The code is attached. Thank you for your time, Chris
I used the c++ for developing, but now perhaps I wil begin use the boost. Is there quick way from standard c++ to boost c++?
I used the c++ for developing, but now perhaps I wil begin use the boost. Is there quick way from standard c++ to boost c++?
Boost is a collection of libraries written in standard c++ and interoperable with the standard c++ library. The most quick way to begin working with boost is to choose the libraries you need and to read the appropriate manuals: http://www.boost.org/doc/libs/1_53_0/
AMDG On 04/05/2013 08:19 AM, Chris Gem wrote:
Please forgive me if this question has been answered but I've searched for days now and cannot find it.
How do I expose a c++ struct with a bit field to python using boost::python?
When I try I get this error.
error: invalid pointer to bit-field ‘frameHdr_s::hdrSize’
You can't take that address of a bitfield. You'll have to use add_property directly. In Christ, Steven Watanabe
Thank you Steve, BOOST_PYTHON_MODULE(api) { class_<FrameHdr>("FrameHdr") //.def_readwrite("hdrSize", &frameHdr_t::hdrSize) .add_property("hdrSize", frameHdr_t) ; Still got the same error. However, after looking at add_property, I wrapped the struct with a class that implemented setters and getters for the bitfields, thusly: typedef struct frameHdr_s { #define USE_BIT_FIELDS #ifdef USE_BIT_FIELDS // Longword 0 uint32_t hdrSize : 16; ///< Size of the header uint32_t revMin : 8; ///< Frame Minor Version uint32_t revMaj : 8; ///< Frame Major Version #else // Longword 0 uint32_t hdrSize; ///< Size of the header uint32_t revMin ; ///< Frame Minor Version uint32_t revMaj ; ///< Frame Major Version #endif } frameHdr_t; class FrameHdr :public frameHdr_t { public: uint32_t getHdrSize() { return hdrSize; } void setHdrSize(uint32_t val) { hdrSize = val; } }; Then I used add_property to expose the setters and getters as the name of the property in question: BOOST_PYTHON_MODULE(api) { class_<FrameHdr>("FrameHdr") //.def_readwrite("hdrSize", &frameHdr_t::hdrSize) .add_property("hdrSize", &FrameHdr::getHdrSize, &FrameHdr::setHdrSize) ; Without trying to sound like too much of a whiner, this seems like a lot of work. Is this what you had in mind? Thanks for your time, Chris
Date: Sat, 6 Apr 2013 13:03:55 -0700 From: watanabesj@gmail.com To: boost-users@lists.boost.org Subject: Re: [Boost-users] c++ Bit Fields
AMDG
On 04/05/2013 08:19 AM, Chris Gem wrote:
Please forgive me if this question has been answered but I've searched for days now and cannot find it.
How do I expose a c++ struct with a bit field to python using boost::python?
When I try I get this error.
error: invalid pointer to bit-field ‘frameHdr_s::hdrSize’
You can't take that address of a bitfield. You'll have to use add_property directly.
In Christ, Steven Watanabe
_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users
participants (4)
-
Chris Gem -
Igor R -
Steven Watanabe -
yujian221