From: David Abrahams (david.abrahams_at_[hidden])
Date: 2001-07-26 11:26:19
This sample code reveals your problem:
void f(vector const& x, vector const& y) { x + y };
It won't compile either, for the same reasons.
your operator+ and operator- should be const member functions. Try adding
const before the opening brace of each one.
-Dave
----- Original Message -----
From: <jfo60540_at_[hidden]>
To: <boost_at_[hidden]>
Sent: Thursday, July 26, 2001 11:55 AM
Subject: [boost] Operator overloading problems with Python 2.1 and gcc 3.0
> Hi -
>
> I am new to boost.python. I compiled the library with Python 2.1.1 and
> gcc
> 3.0 under Solaris 2.7. There were a few minor problems (gcc stl
> headers
> are broken and std::sin(float) and std::cos(float) are left undefined
> ),
> but I eventually got all the tests (in particular comprehensive.py)
> to
> work properly. I then tried the following code to test
> the operator overloading feature:
>
>
> #include <iostream>
>
> class vector {
> protected:
> int x;
> int y;
> public:
> vector(int a=0,int b=0) {
> x = a;
> y = b;}
> void set_values(int a, int b) {
> x=a;
> y=b;}
> vector operator+ (const vector operand) {
> vector z;
> z.x = x + operand.x;
> z.y = y + operand.y;
> return z;}
> vector operator- (const vector operand) {
> vector z;
> z.x = x - operand.x;
> z.y = y - operand.y;
> return z;}
> };
>
> #include <boost/python/class_builder.hpp>
> namespace python = boost::python;
> BOOST_PYTHON_MODULE_INIT(over)
> {
> try
> {
> python::module_builder over("over");
> python::class_builder<vector> vector_class(over, "vector");
> vector_class.def(python::constructor<int,int>());
> vector_class.def(&vector::set_values, "set_values");
> vector_class.def(boost::python::operators<(boost::python::op_add |
> boost::python::op_sub)>());
> }
> catch(...)
> {
> python::handle_exception(); // Deal with the exception for Python
> }
> }
>
>
> Compilation of the above fails with the following error messages:
>
> /usr/local/ap/include/boost/python/operators.hpp: In member function
> `PyObject*
> boost::python::detail::define_operator<2>::operator_function<Left,
> Right>::do_call(PyObject*, PyObject*) const [with Left = const
> vector&,
> Right = const vector&]':
> /usr/local/ap/include/boost/python/detail/extension_class.hpp:861:
> instantiated from here
> /usr/local/ap/include/boost/python/operators.hpp:295: passing `const
> vector' as
> `this' argument of `vector vector::operator-(vector)' discards
> qualifiers
> /usr/local/ap/include/boost/python/operators.hpp: In member function
> `PyObject*
> boost::python::detail::define_operator<1>::operator_function<Left,
> Right>::do_call(PyObject*, PyObject*) const [with Left = const
> vector&,
> Right = const vector&]':
> /usr/local/ap/include/boost/python/detail/extension_class.hpp:861:
> instantiated from here
> /usr/local/ap/include/boost/python/operators.hpp:294: passing `const
> vector' as
> `this' argument of `vector vector::operator+(vector)' discards
> qualifiers
>
>
> Any help would be appreciated.
>
>
>
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>