Quick help on QProcess

[devilj]

I am trying to use QProcess to call a perl script. Here is my code:

Window.h

private slots:
                 void processIT();
                 void output(const QString &text);
private:
                QProcess process;

private slots:
                 void processIT();
                 void output(const QString &text);
private:
                QProcess process;

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Window.cpp

void Window::processIT()
 {
 	connect(process,SIGNAL(readyReadStandardOutput()),
		this,SLOT(output(const QString &)));
	connect(process,SIGNAL(readyReadStandardError(const QString &)),
	this,SLOT(output()));
 	QString path(dirEdit->text());
 	QString program("perl /home/jim/perlQt/moalq.pl ");
 	program += path;
 	process.start(program);
}
 
//....
 
void Window::output(const QString &text)
{
	out->append(text);   
 
}

void Window::processIT()
 {
 	connect(process,SIGNAL(readyReadStandardOutput()),
		this,SLOT(output(const QString &)));
	connect(process,SIGNAL(readyReadStandardError(const QString &)),
	this,SLOT(output()));
 	QString path(dirEdit->text());
 	QString program("perl /home/jim/perlQt/moalq.pl ");
 	program += path;
 	process.start(program);
}

//....

void Window::output(const QString &text)
{
	out->append(text);   
	 
}

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my app compiles but I get the following at runtime:
[HTML]Object::connect: No such slot Window:rocess()[/HTML]


Any ideas?

[marcel]

First of all, this is not correct:

connect(process,SIGNAL(readyReadStandardOutput()),
        this,SLOT(output(const QString &)));

connect(process,SIGNAL(readyReadStandardOutput()),
        this,SLOT(output(const QString &)));

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A slot may have a shorter signature than the incoming signal, but not the way around.
Hint: make the parameter for output a default one:

void output(const QString &text = "");
...
connect(process,SIGNAL(readyReadStandardOutput()),
        this,SLOT(output()));

void output(const QString &text = "");
...
connect(process,SIGNAL(readyReadStandardOutput()),
        this,SLOT(output()));

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This will work.

As for the runtime error, that does not make any sense unless you have somewhere in your application a slot called process or you try connecting a signal to an nonexistent process() slot.

Regards

[jacek]

QObject::connect: No such slot Window::process()

Shouldn't it be processIT()?

[marcel]

Shouldn't it be processIT()?

Yes, that confuses me too.
Maybe it is just a copy paste error.

But, if it is processIT, where do you connect to processIT? Could you post that code too?

Regards

[devilj]

You guys are right!


I had this for my process button:
processButton = createButton(tr("&Process"), SLOT(process()));

should be ...SLOT(processIT()));

A slot may have a shorter signature than the incoming signal, but not the way around.
Hint: make the parameter for output a default one:

Should I forget about passing a parameter to the output() function.
in essence:

//......
connect(&process,SIGNAL(readyReadStandardOutput()),
		this,SLOT([B]output()[/B]));
//.......

//......
connect(&process,SIGNAL(readyReadStandardOutput()),
		this,SLOT([B]output()[/B]));
//.......

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and then setup output as:

void Window::output()
{
	out->append(QString(process.readyReadStandardOutput()));   
}

void Window::output()
{
	out->append(QString(process.readyReadStandardOutput()));   
}

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