Overloading QDataStream & operator<< , operator>> in namespace

bright day

Hi! I need to overload operator<< and operator>> in order to write to and read from QDataStream these 2 types: QList<QList<QString> > and QMap<QString, QString>.
(For QMap<QString, QString> I can simply call
@operator<< <QString,QString>(out,map)@

but for to have similar calls to both QList<QList<QString> and QMap<QString, QString>, I overload the last one too ).

SO, code:
@
#ifndef OPERATORS_H
#define OPERATORS_H

#include <QDataStream>

namespace operatorsNamespace
{

QDataStream & operator<< ( QDataStream & out, const QMap<QString, QString> & map )
{
    return operator<< <QString, QString> (out,map);
}

QDataStream & operator>> ( QDataStream & in, QMap<QString, QString> & map )
{
    return operator>> <QString,QString>(in,map);
}

QDataStream& operator>>(QDataStream& s, QList<QList<QString> >& l)
{
    l.clear();
    quint32 c;
    s >> c;
    l.reserve(c);
    for(quint32 i = 0; i < c; ++i)
    {
        QList<QString> t;
        operator>> <QString> (s, t);
        l.append(t);
        if (s.atEnd())
            break;
    }
    return s;
}

QDataStream& operator<<(QDataStream& s, const QList<QList<QString> >& l)
{
    s << quint32(l.size());
    for (int i = 0; i < l.size(); ++i)
        operator<< <QString> (s, l.at(i));
    return s;
}

}
#endif // OPERATORS_H

@

The issue is that, when I remove namespace wrapper, and call
@
QMap <QString,QString> fields;
QList <QList<QString> > content;
operator>>(str,fields);
operator>>(str,content);
@

it's ok, program goes through these operators (stops at breakpoints). But when I add namespace wrapper, and call
@
operatorsNamespace::operator>>(str,fields);
operatorsNamespace::operator>>(str,content);
@

, I get the following compiler errors :
@
In file included from client.cpp:18:
operators.h: In function 'QDataStream& operatorsNamespace::operator<<(QDataStream&, const QMap<QString, QString>&)':
operators.h:11: error: expected primary-expression before ',' token
operators.h:11: error: expected primary-expression before '>' token
operators.h:11: warning: left-hand operand of comma has no effect
operators.h: In function 'QDataStream& operatorsNamespace::operator>>(QDataStream&, QMap<QString, QString>&)':
operators.h:16: error: expected primary-expression before ',' token
operators.h:16: error: expected primary-expression before '>' token
operators.h:16: warning: left-hand operand of comma has no effect
operators.h: In function 'QDataStream& operatorsNamespace::operator>>(QDataStream&, QList<QList<QString> >&)':
operators.h:28: error: expected primary-expression before '>' token
operators.h:28: warning: left-hand operand of comma has no effect
operators.h: In function 'QDataStream& operatorsNamespace::operator<<(QDataStream&, const QList<QList<QString> >&)':
operators.h:40: error: expected primary-expression before '>' token
operators.h:40: warning: left-hand operand of comma has no effect
@

Please, help me with this. Thanks in advance, gurus..

andre

Weird that you need to implement the operator at all. After all, in the QList documentation you can find that there already is a an implemenation for operator<<() and operator>>(), that are supported for all types that themselves support these operators. As QString supports them, so should QList<QString>, and thus so should QList<QList<QString> > .

goetz

I'm not a namespace expert, but from my understanding:

QDataStream is in global Namespace (or Qt namespace). So I would try ::QDataStream, as QDataStream would refer to a member within your current namespace.

Albeit, Andre is correct: Why do you need to implement the operators in the first place?