CODEWITHSUNDEEP
c++qt
Charles Curt
Charles Curt

Reputation: 69

Call a script in parallel in Qt C++

I am trying to run a script in parallel to my Qt program and am having trouble starting it as a separate process. Check out my attempts below and let me know what you see wrong.

The first attempt was just a system call:

system("python3 startprocess.py");

This works but it also stops the program while running it.

I then followed this guy https://forum.qt.io/topic/92205/writing-commands-to-linux-bash with no success. No errors, just no start of my script.

I am trying this after I saw the documentation and have the below code.

QProcess process;
process.start("python3 startprocess.py");
process.waitForStarted();

I am just wanting to start this script and have it run at the same time as my C++ code. Perhaps I am using the QProcess wrong?

UPDATE: It was a lot easier to use QThreading and the original system call.

Upvotes: 0

Views: 276

Answers (1)

Andrea Ricchi
Andrea Ricchi

Reputation: 490

I think the issue is that the QProcess doesn't have the file path and fails to find and start it! I suggest first to use the full file path! Also check the QProcess::setWorkingDirectory and QProcess::setProcessEnvironment that are useful to handle this case!

Update

In order to prevent the QProcess to be killed while running and without freezing the GUI, you need to define it as a pointer, then connect the QProcess::finished event; in the slot, you can check the exit code and delete the sender using QObject::deleteLater method. Check both the Qt example and the QProcess::finished.

Update 2

Try this code:

auto process = new QProcess(this);
connect(process, QOverload<int,QProcess::ExitStatus>::of(&QProcess::finished), 
[this](int exitCode, QProcess::ExitStatus exitStatus) 
{
    if (exitStatus == QProcess::ExitStatus::CrashExit 
        || exitCode != 0) {
        // Process error!
    } else {
        // Process OK!
    }
});
process->setWorkingDirectory("startprocess.py folder location");
process->start("python3 startprocess.py");
if (!process->waitForStarted(-1)) {
    // Failed to start process
    delete process;
}

Upvotes: 1

Related Questions