[Interest] Connecting output of an external process to a QML component

[Daniel França]

Thanks guys, I was blind by the new year eve and couldn't see this capital
E messing up my code.
I changed my call to start the process to pass a single string instead of a
QStringList of arguments (it's calling a python script) and it worked.
Still want to investigate why it's working only this way, but thanks for
all the help.

Em Thu Jan 01 2015 at 4:20:17 PM, Alejandro Exojo <suy at badopi.org> escreveu:

> El Wednesday 31 December 2014, Daniel França escribió:
> > I'm instantiating the C++ class via setContextProperty, so it's a
> singleton
> > object.
>
> I would not say that this is a singleton object. You register one already
> instantated object instead of a class, but it could be or not a singleton.
>
> > Then I start the process, and connect the signal/slot:
> > http://pastebin.com/p2CyZwfh
> >
> > Here's the first problem... the slot is never being called.
> > The slot should be called and then emit another signal (that I could
> > connect to QML): http://pastebin.com/Zvj1Y11w
> >
> > The other problem is that QML can't recognize this signal:
> > http://pastebin.com/QWkkk5mT
> > Giving me the error: *Cannot call method 'connect' of undefined*
> > and of course, the signal is defined: http://pastebin.com/rxsnQNke
>
> This is a horrible way to show your code. You are pasting 2 line snippets
> without any context.
>
> I see the same mistake that Dmitry saw for starters: in QML you have to
> follow
> Qt's conventions or is likely that you are doing it wrong. Only types begin
> with "Capital" letter. Not only that. In the other paste you are writing it
> beginning with a lower case first letter.
>
> > Googling around all the examples I see are using the QMLRegisterType
> > instead, to connect signals/slots, should I move to this way? It's not
> > possible to connect with singleton/context objects?
>
> Unrelated. Think of the way you are using a way to make one object alone
> (or
> several if you instantiate more, but one at a time). the qmlRegisterType is
> for registering a class as a QML object type.
>
> > Of course, if there's an easier way to show the standard output of
> another
> > process to a QML component I would love to know.
>
> Depends on what you want to achieve. If for example you want to launch a
> process and show it's stdout in a TextEdit element I would wrap the
> QProcess
> in a subclass that keeps a Q_PROPERTY updated with the contents of that
> output. That would be probably more efficient, since instead of passing a
> string list through the signal, you follow the usual pattern of signaling
> only
> that new content is available, and using a "getter" to get those conents,
> instead of passing them all in the signal. That's what Qt does (e.g. your
> QProcess doesn't pass all the output contents in the signal; you react to
> the
> signal and call readAllStandardOutput() in the slot).
>
> --
> Alex (a.k.a. suy) | GPG ID 0x0B8B0BC2
> http://barnacity.net/ | http://disperso.net
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