QtRuby emit does not work

Question

Platform:

Darwin *-*s-MacBook-Pro.local 11.4.2 Darwin Kernel Version 11.4.2: Thu Aug 23 16:25:48 PDT 2012; root:xnu-1699.32.7~1/RELEASE_X86_64 x86_64

Ruby:

ruby 2.0.0p0 (2013-02-24 revision 39474) [x86_64-darwin11.4.2] (installed by rvm)

Qt:

qt: stable 4.8.4 (bottled), HEAD

Code:

require 'Qt'

class Foo < Qt::Object

    signals :my_signal #also tried 'my_signal()'
    slots 'my_slot()'

    def initialize(parent = nil)
        super(parent)

        puts "connecting signal and slot"
        Qt::Object.connect(self, SIGNAL('my_signal()'), self, SLOT('my_slot()'))
        # also tried => connect(self, SIGNAL('my_signal()'), self, SLOT('my_slot()'))

    end

    def emit_my_signal
        puts "sending signal"
        emit my_signal
    end

    def my_slot
        puts "received message from signal"
    end
end


o = Foo.new
o.emit_my_signal

Output:

connecting signal and slot
sending signal

Output with Qt.debug_level = Qt::DebugLevel::High

Munged method names:
        QObject$
        QObject?
        QObject#
candidate list:
    QObject* QObject::QObject(QObject*)  (smoke: 0 index: 3804)
matching => smoke: 0 index: 3804
        QObject* (u) score: 2
        match => smoke: 0 index: 3804 score: 2 chosen: 3804
setCurrentMethod(smokeList index: 0, meth index: 3804)
connecting signal and slot
Searching for QObject#connect
Munged method names:
        connect#$#$
candidate list:
    static bool QObject::connect(const QObject*, const char*, const QObject*, const char*)  (smoke: 0 index: 3850)
matching => smoke: 0 index: 3850
        const QObject* (QObject) score: 3
        const char* (s) score: 1
        const QObject* (QObject) score: 3
        const char* (s) score: 1
        match => smoke: 0 index: 3850 score: 8 chosen: 3850
setCurrentMethod(smokeList index: 0, meth index: 3850)
sending signal

it seems emit does not do anything. I have also tried reinstall qt and qtbindings, but the problem still exists. And also I tried PyQt with signal and slot on the same machine, it works like a charm.

Does anybody have any ideas about this? Is it a bug of ruby qtbindings or I just did something wrong?

Answer 1

Usually, one needs to start Qt's event loop before any signals can be reliably delivered. I don't see that in your code. More specifically, what I'm missing is:

app = Qt::Application.new(ARGV)
app.exec