Sequential execution of QProcesses

[scottaronbloom]

Lesiok's option is probably the least effort. Here are some other options:

Create a slot for each step. In the slot for step 1 start the relevant process and connect() its finished() signal to the slot for step 2... and so on. You should check the exit state of step n at the top of step n+1 before starting the new step's process.

Or, between steps:

QEventLoop loop;
connect(process, SIGNAL(finished(...)), &loop, SLOT(quit()));
loop.exec();

QEventLoop loop;
connect(process, SIGNAL(finished(...)), &loop, SLOT(quit()));
loop.exec();

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The problem here, is you are assuming that the QProcess is still running when you start the event loop.

With the following code

QProcess process;
QEventLoop loop;
connect(process, SIGNAL(finished(...)), &loop, SLOT(quit()));
process.start();
loop.exec()

QProcess process;
QEventLoop loop;
connect(process, SIGNAL(finished(...)), &loop, SLOT(quit()));
process.start();
loop.exec()

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its possible for short running executables that the process ends before the loop.exec command. This has bit me in the butt more than once.

The best solution I have come up with is the following

QProcess process;
QEventLoop loop;
bool processFinished = false;
connect(process, &QProcess::finished, 
[&loop, &processFinished]()
{
    processFinished = true;
    if ( loop.isRunning() )
         loop.exit();
}
)
process.start();
loop.exec()

QProcess process;
QEventLoop loop;
bool processFinished = false;
connect(process, &QProcess::finished, 
[&loop, &processFinished]()
{
    processFinished = true;
    if ( loop.isRunning() )
         loop.exit();
}
)
process.start();
loop.exec()

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