Hi everyone,
I experimented a bit with stream iterators following one of Danny's
"10-Minute-Solutions". Great stuff, but I hit a problem when I tried
to use the same techique for a nested class template. I attach the code
if you want to reproduce the problem. The thing that puzzles me is, that
I can manually iterate through the list of nested class objects and use
the stream operator, but cannot compile when I try to use the std::copy()
algorithm. Am I missing anything here or is this a (known?) deficiancy of
STL or more likely Microsofts implementation of it?
Any tips welcome...

Thanks,

Dieter

// OStrTest.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <string>
#include <vector>
#include <iostream>
#include <fstream>
#include <iterator>
using namespace std;

template <class X>
class my_class
{
public:
class sub
{
string str;
public:
sub(string s)
: str(s)
{
}
friend ostream& operator << (ostream& os, const sub& s);
friend class my_class<X>;
};
private:
X member1;
X member2;
vector<sub> strs;
public:
my_class(X m1 = 0,X m2 = 0)
{
member1 = m1;
member2 = m2;
strs.push_back(string("str1"));
strs.push_back(string("str2"));
strs.push_back(string("str3"));
strs.push_back(string("str4"));
}
friend ostream& operator << (ostream& os, my_class<X>& mcl);
};

template <class X>
ostream& operator << (ostream& os, const my_class<X>::sub& s)
{
os << " - " << s.str << endl;
return os;
}

template <class X>
ostream& operator << (ostream& os, my_class<X>& mcl)
{
os << "(" << mcl.member1 << "," << mcl.member2 << ")" << endl;
for(vector<my_class<X>::sub>::iterator it=mcl.strs.begin(); it != mcl.strs.end() ; it++)
cout << (*it);
//
// UNCOMMENTING THE NEXT LINE PRODUCES THE FOLLOWING ERROR:
//
// c:\program files\microsoft visual studio\vc98\include\iterator(203) :
// error C2679: binary '<<' : no operator defined which takes a right-hand operand
// of type 'const class my_class<int>::sub' (or there is no acceptable conversion)
// c:\program files\microsoft visual studio\vc98\include\iterator(203) :
// while compiling class-template member function
// 'class std::ostream_iterator<class my_class<int>::sub,char,struct std::char_traits<char> >
// &__thiscall std::ostream_iterator
// <class my_class<int>::sub,char,struct std::char_traits<char> >::operator =
// (const class my_class<int>::sub &)'

// This line produces the error
// std::copy(mcl.strs.begin(),mcl.strs.end(),ostream_iterator<my_class<X>::sub> (os, " "));
return os;
}

int main(int argc, char* argv[])
{
my_class<int> mcl1(3,5);
cout << mcl1 << endl;
my_class<double> mcl2(3.14159265,5.678);
cout << mcl2 << endl;
return 0;
}