DeleteLater and 2 slots

qtprogrammer123

Hi, i wonna ask if i have guaranti that deleteReplay slot will invoke after reciving slots - if i put deleteLater in reciving slots app crashing

void Modbus::ModbusDevice::readOutputs(int addr, int count, QString name, int id, QModbusDataUnit::RegisterType registerType)
{
    devName = name;

    QModbusDataUnit readUnit(registerType, addr, count);

    if (auto *reply = modbus->sendReadRequest(readUnit, 1)) {
        if (!reply->isFinished()) {
            if(id == 3) {
                connect(reply, &QModbusReply::finished,this,&ModbusDevice::onReadOutputsFinished);
            }
            else connect(reply, &QModbusReply::finished,this,&ModbusDevice::onReadFinished);
            
            connect(reply, &QModbusReply::finished, this, &ModbusDevice::deleteReply);
            
        } else {
            delete reply;
        }
    }
}
void Modbus::ModbusDevice::deleteReply()
{
    QModbusReply *reply = qobject_cast<QModbusReply *>(sender());
    reply->deleteLater();
}

jsulm

@qtprogrammer123 said in DeleteLater and 2 slots:

QModbusReply *reply = qobject_cast<QModbusReply *>(sender());
reply->deleteLater();

You're not checking the pointer: if it's nullptr it will crash.
You're connecting QModbusReply::finished to ModbusDevice::deleteReply and to ModbusDevice::onReadFinished - why don't you simply call deleteLater inside ModbusDevice::onReadFinished?