how to pass python method and kwargs to boost python c++ function and call
how do I pass a python method and kwargs to a boost C++ function and call the python method with kwargs.
python:
def py_method(**kwargs):
for key in kwargs.keys():
print 'Key: ', key, ', Value: ', kwargs[key]
cpp_method(py_method, arg1=1, arg2=2)
or
kwargs = {'arg1': 1, 'arg2': 2}
cpp_method(py_method, **kwargs)
C++: please help me to correct the below code.
using namespace boost::python;
void cpp_method(object py_method, object kwargs)
py_method(kwargs)
Thanks to Dan MaĊĦek for pointing this link
Compiled on MacOS HighSierra and getting segmentation fault:
g++ -std=c++11 -I/Library/Frameworks/Python.framework/Versions/2.7/Headers -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"foo.d" -MT"foo.o" -o "foo.o" foo.cpp
g++ -L/usr/local/lib -L/Library/Frameworks/Python.framework/Versions/2.7/ -shared -o foo.so ./foo.o -lboost_python27 -lPython
$ python
Python 2.7.14 (v2.7.14:84471935ed, Sep 16 2017, 12:01:12)
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import foo
>>> dir(foo)
['__doc__', '__file__', '__name__', '__package__', 'cpp_method']
>>> def py_method(**kwargs):
... print 'from py_method'
... print kwargs
...
>>> kwargs = {'arg1': 1, 'arg2': 2}
>>> foo.cpp_method(py_method, kwargs)
Segmentation fault: 11
Process: Python [22790]
Path: /Library/Frameworks/Python.framework/Versions/2.7/Resources/Python.app/Contents/MacOS/Python
Identifier: Python
Version: 2.7.14 (2.7.14)
Code Type: X86-64 (Native)
Parent Process: bash [368]
Responsible: Python [22790]
User ID: 501
Date/Time: 2018-10-04 16:54:51.618 -0700
OS Version: Mac OS X 10.13.6 (17G65)
Report Version: 12
Anonymous UUID: 3A7BC812-2E65-69A4-936B-21E5CE648BCF
Sleep/Wake UUID: E32B82BD-2B4C-4220-A9C2-F71FF57DDA56
Time Awake Since Boot: 580000 seconds
Time Since Wake: 2700 seconds
System Integrity Protection: disabled
Crashed Thread: 0 Dispatch queue: com.apple.main-thread
Exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0x0000000000000048
Exception Note: EXC_CORPSE_NOTIFY
Termination Signal: Segmentation fault: 11
Termination Reason: Namespace SIGNAL, Code 0xb
Terminating Process: exc handler [0]
VM Regions Near 0x48:
-->
__TEXT 0000000100000000-0000000100001000 [ 4K] r-x/rwx SM=COW /Library/Frameworks/Python.framework/Versions/2.7/Resources/Python.app/Contents/MacOS/Python
Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0 org.python.python 0x00007fff3bfaec5c PyErr_Occurred + 14
1 org.python.python 0x00007fff3bf2bdf5 PyObject_IsInstance + 401
2 foo.so 0x0000000100799aaf boost::python::converter::pyobject_type::check(_object*) + 31 (pyobject_type.hpp:24)
3 foo.so 0x0000000100799918 boost::python::converter::object_manager_value_arg_from_python::convertible() const + 24 (obj_mgr_arg_from_python.hpp:69)
4 foo.so 0x00000001007997e1 boost::python::detail::caller_arity::impl >::operator()(_object*, _object*) + 129 (local.hpp:37)
5 foo.so 0x00000001007996e4 boost::python::objects::caller_py_function_impl > >::operator()(_object*, _object*) + 52 (py_function.hpp:38)
6 libboost_python27.dylib 0x000000010190e1a4 boost::python::objects::function::call(_object*, _object*) const + 820
7 libboost_python27.dylib 0x0000000101910d5a boost::detail::function::void_function_ref_invoker0::invoke(boost::detail::function::function_buffer&) + 26
8 libboost_python27.dylib 0x0000000101916f48 boost::python::handle_exception_impl(boost::function0) + 72
9 libboost_python27.dylib 0x0000000101910871 boost::python::objects::function_call(_object*, _object*, _object*) + 81
10 org.python.python 0x000000010000c2e2 PyObject_Call + 98
11 org.python.python 0x00000001000c30b1 PyEval_EvalFrameEx + 15777
12 org.python.python 0x00000001000cac23 PyEval_EvalCodeEx + 2115
13 org.python.python 0x00000001000cad46 PyEval_EvalCode + 54
14 org.python.python 0x00000001000ef7ec PyRun_InteractiveOneFlags + 380
15 org.python.python 0x00000001000efa4e PyRun_InteractiveLoopFlags + 78
16 org.python.python 0x00000001000f0261 PyRun_AnyFileExFlags + 161
17 org.python.python 0x00000001001071dd Py_Main + 3101
18 org.python.python 0x0000000100000f14 0x100000000 + 3860
Thread 0 crashed with X86 Thread State (64-bit):
rax: 0x0000000000000000 rbx: 0x0000000000000002 rcx: 0x0000000000000001 rdx: 0x0000000000000003
rdi: 0x00007fff8cc80458 rsi: 0x00000001007b4030 rbp: 0x00007ffeefbff210 rsp: 0x00007ffeefbff210
r8: 0x00000001007b4030 r9: 0x8c8bb1dcac69804a r10: 0x0000000000001002 r11: 0xffff8001c47c5769
r12: 0x0000000000000000 r13: 0x0000000100702a70 r14: 0x0000000100728280 r15: 0x00007fff8cc784f0
rip: 0x00007fff3bfaec5c rfl: 0x0000000000010246 cr2: 0x0000000000000048
Logical CPU: 3
Error Code: 0x00000004
Trap Number: 14
Binary Images:
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Calls made by other processes targeting this process:
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Calls made by this process:
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Calls made by all processes on this machine:
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VM Region Summary:
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Model: MacBookPro12,1, BootROM MBP121.0177.B00, 2 processors, Intel Core i7, 3.1 GHz, 16 GB, SMC 2.28f7
Graphics: Intel Iris Graphics 6100, Intel Iris Graphics 6100, Built-In
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Serial ATA Device: APPLE SSD SM0512G, 500.28 GB
USB Device: USB 3.0 Bus
USB Device: Bluetooth USB Host Controller
Thunderbolt Bus: MacBook Pro, Apple Inc., 27.1
1 Answer
I solved it with pybind11, much easier than boost-python
cpp.cpp:
#include <pybind11/pybind11.h>
#include <iostream>
namespace py = pybind11;
void cpp_method(py::object method, py::kwargs kw) {
py::object obj = method(**kw);
std::cout << "Printing from cpp: " << std::string(py::str(obj)) << std::endl;
}
PYBIND11_MODULE(cpp, mod) {
mod.def("cpp_method", &cpp_method);
}
compilation:
c++ -O3 -Wall -shared -std=c++11 -fPIC `python -m pybind11 --includes` cpp.cpp -o cpp.so `python-config --ldflags`
python:
$ python
Python 2.7.14 (v2.7.14:84471935ed, Sep 16 2017, 12:01:12)
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import cpp
>>> dir(cpp)
['__doc__', '__file__', '__name__', '__package__', 'cpp_method']
>>> def py_method(**kwargs):
... print 'Printing from python, kwargs: ', kwargs
... return 'py_method return string'
...
>>> cpp.cpp_method(py_method, a=1, b=2, c=3)
Printing from python, kwargs: {'a': 1, 'c': 3, 'b': 2}
Printing from cpp: py_method return string
answered on Stack Overflow Oct 14, 2018 by 
user3713719
user3713719User contributions licensed under CC BY-SA 3.0