Using Boost Python for C++ class which takes user input - c++

Question

I have a C++ class which takes user input in the constructor and then writes that (and other stuff) onto a file. It works perfectly fine on C++ (both on MSVC and GCC) and now I would like to use this class in my Python projects. My files are:
foo.h
#include <iostream>
#include <fstream>
#include <stdio.h>
class Foo
{
public:
explicit Foo(const std::string file_name, const std::string other_input);
virtual ~Foo();
void Write(const std::string random_text);
private:
std::ofstream output_file;
char buffer[200];
std::string random_string;
};
foo.cpp
#include <Python.h>
#include <boost/python.hpp>
#include <boost/shared_ptr.hpp>
// Constructor
Foo::Foo(const std::string file_name, const std::string other_input)
{
std::ifstream file_exists(file_name)
if(file_exists.good())
output_file.open(file_name, std::ios_base::app);
else
output_file.open(file_name);
random_string = other_input;
}
// Destructor
Foo::~Foo()
{
output_file.close();
}
// Write to a file
void Foo::Write(const std::string random_text)
{
sprintf( buffer, "%s", random_string );
output_file << buffer << ";\n";
}
// Boost.Python wrapper
BOOST_PYTHON_MODULE(foo)
{
boost::python::class_<Foo>("Foo", boost::python::init<>())
.def("Write", &Foo::Write)
;
}
When I try to compile this on Visual Studio or GCC, I am getting the following error:
'std::basic_ofstream<_Elem,_Traits>::basic_ofstream' : cannot access private member declared in class 'std::basic_ofstream<_Elem,_Traits>'
I am totally confused regarding why this is the case. I have tried another variant of the wrapper, namely:
// Boost.Python wrapper
BOOST_PYTHON_MODULE(foo)
{
boost::python::class_<Foo, boost::noncopyable>("Foo", boost::python::init<>())
.def("Write", &Foo::Write)
;
}
And here I get the error:
'Foo' : no appropriate default constructor available
Any ideas to get this to heel would be highly appreciated!
Thanks in advance..

Answer 1

One apparent mistake in your code is that Foo's constructor takes two parameters that you have not included in the wrapper:
// Boost.Python wrapper
BOOST_PYTHON_MODULE(foo)
{
boost::python::class_<Foo, boost::noncopyable>("Foo",
boost::python::init<const std::string, const std::string>())
.def("Write", &Foo::Write)
;
}
This explains the second error and this version (with noncopyable) should now compile fine.