qvariant_test.cpp

qvariant_test.cpp

#include <stdio.h>
#include <stdlib.h>
#include <iostream>
#include <QObject>
#include <QVariant>
#include <QDebug>

using namespace std;

template <typename A>
A arg(const QVariant& arg)
{
    return arg.value<A>();
}

template<>
int arg<int>(const QVariant& arg)
{
    bool ok = false;
    int intVal = arg.toInt(&ok);
    if (ok) return intVal;
    double dblVal = arg.toDouble(&ok);
    if (ok) return static_cast<int>(dblVal + 0.5);
    return 0;
}

template <typename A>
QVariant makeReturn(const A& val)
{
    return QVariant(val);
}

template <typename A1, typename A2, typename RET>
QVariant add(const QVariant& a1, const QVariant& a2)
{
    return makeReturn<RET>(static_cast<RET>(arg<A1>(a1) + arg<A2>(a2)));
}

int main(int argc, char* argv[])
{
    Q_UNUSED(argc)
    Q_UNUSED(argv)
    qDebug() << add<int,int,int>("2.142857", "3.571428");
    qDebug() << add<int,double,int>("2.142857", "3.571428");
    qDebug() << add<int,double,double>("2.142857", "3.571428");
    qDebug() << add<double,double,double>("2.142857", "3.571428");

    //qDebug() << makeReturn<double>(3.14159265358979323);
    //qDebug() << QVariant(3.14159265358979323);
    return 0;
}