Your Boost.Python usage is fine. It's the Python code that inherently
won't work:
>> from MyModule import *
>> mc = MyClass()
>> p = []
>> mc.myFuncSet(p)
Here, 'p' doesn't actually have a std::vector in it - it's a regular
Python list, so Boost.Python can't get a std::vector reference out of it.
Instead you can do:
>> from MyModule import *
>> mc = MyClass()
>> p = MyList()
>> mc.myFuncSet(p)
One could imagine writing a fancy converter that would allow the first
form by making a temporary std::vector, passing that to the C++
function, and then copying the elements in the vector back into the
Python list. But that's potentially a very expensive sequence of
operations, and it's actually impossible to do that through a registered
converter in Boost.Python. If you really want that Python syntax to
work, you'll have to write a C++ function that takes a
boost::python::list argument and calls the actual C++ function that
operates on std::vector.
Jim
On 01/21/2012 11:40 AM, DeVico, Mike wrote:
Hello,
I would like to wrap a class that looks like below (taken from an
example I found on another site)
#include <boost/python.hpp>
#include <boost/python/suite/indexing/vector_indexing_suite.hpp>
#include <boost/python/suite/indexing/map_indexing_suite.hpp>
typedef std::vector<std::string> MyList;
class MyClass {
public:
MyList myFuncGet()
{
return MyList();
}
void myFuncSet(MyList& list)
{
list.push_back("Hello");
}
// stuff
};
BOOST_PYTHON_MODULE(MyModule)
{
class_<MyList>("MyList")
.def(vector_indexing_suite<MyList>() );
class_<MyClass>("MyClass")
.def("myFuncGet", &MyClass::myFuncGet)
.def("myFuncSet", &MyClass::myFuncSet)
;
}
However, this is what I get when I try to use it from python:
Python 2.7.2 (default, Jun 12 2011, 14:24:46) [MSC v.1500 64 bit
(AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>> from MyModule import *
>> mc = MyClass()
>> p = []
>> mc.myFuncSet(p)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
Boost.Python.ArgumentError: Python argument types in
MyClass.myFuncSet(MyClass, list)
did not match C++ signature:
myFuncSet(MyClass {lvalue}, std::vector<std::string,
std::allocator<std::string> > {lvalue})
>>
I know I’m missing a converter function, but I’m new to boost and I
don’t know what the converter
should look like in this case.
I’ve found lots of working examples of how to return a vector, but I
want to be able to pass the vector
into the function by reference and modify it.
I would really appreciate it if someone could complete the example by
adding the necessary converter
code.
Thanks in advance.
--Mike
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