boost::assign for a set not working with +=

Question

I am trying to use Boost::assign and the operator += to initialize a static set that I am planning to use later. I followed the steps specified in this link. The code is split across three files

/*Assign.hpp*/
#ifndef __SAMPLE_CLASS__
#define __SAMPLE_CLASS__

#include <iostream>
#include <set>
#include <string>
#include <boost/assign/std/set.hpp>

class SampleClass
{
    public:
        SampleClass();
        ~SampleClass();

        typedef std::set<int> SET_TYPE;

        static const SET_TYPE my_set1;
        static const SET_TYPE my_set2;
};

#endif

/*Assign.cpp*/
#include "assign.hpp"

using namespace boost::assign;

const SampleClass::SET_TYPE SampleClass::my_set1 += 1,2,3;
const SampleClass::SET_TYPE SampleClass::my_set2 += 4,5,6;

SampleClass::SampleClass()
{

}

SampleClass::~SampleClass()
{

}

/*main.cpp*/
#include "assign.hpp"                    

int main()
{
    SampleClass sobj;
    return 0;
}

I get the following compilation error when I issue the following command

g++ -I /usr/local/include main.cpp assign.cpp

Error snippet

assign.cpp:6:50: error: invalid '+=' at end of declaration; did you mean '='?
const SampleClass::SET_TYPE SampleClass::my_set1 += 1,2,3;
                                             ^~
                                             =
assign.cpp:6:42: error: no viable conversion from 'int' to 'const SampleClass::SET_TYPE' (aka 'const set<int>')
const SampleClass::SET_TYPE SampleClass::my_set1 += 1,2,3;
                                     ^          ~
assign.cpp:6:55: error: expected unqualified-id
const SampleClass::SET_TYPE SampleClass::my_set1 += 1,2,3;
                                                  ^
assign.cpp:6:55: error: expected ';' after top level declarator
const SampleClass::SET_TYPE SampleClass::my_set1 += 1,2,3;

...

Is there something wrong in the way I am trying to initialize my static set or my usage of the += operator here?

Answer 1

You can change it like this if your compiler supports c++11:

const SampleClass::SET_TYPE SampleClass::my_set1 = {1,2,3};
const SampleClass::SET_TYPE SampleClass::my_set2 = {4,5,6};

Answer 2

You can't use += in an initialization statement.