[Kde-bindings] questions about signals and slots in qruby4

[Stefano Crocco]

I have a few questions about signals, slots and connections in qtruby4:

* 'connect' if called with an explicit receiver wants a block and raises an 
error if called in the non-block form. For example, the following code works:

require 'Qt4'

app =  Qt::Application.new []
btn = Qt::PushButton.new "Sender"
label = Qt::Label.new "Receiver"
btn.connect(SIGNAL('clicked()')){label.clear}
btn.show
label.show
app.exec

but if I replace the connect line with:

btn.connect(SIGNAL('clicked()'), label, SLOT('clear()'))

I get the following error:

./prova.rb:9:in `method_missing': super: no superclass method `connect' 
(NoMethodError)
        from ./prova.rb:9:in `connect'
        from ./prova.rb:9

(At first, I thought the error might have had been caused by calling connect 
from the top-level object, given that it spoke about a missing superclass 
method, but trying it inside an instance method of a Qt::Widget-derived class 
gave the same result). Is this wanted, or is it a bug? If it is wanted, is 
there another way to make a connection outside from an instance method of a 
Qt::Object-derived object? In C++ (I think) you can write:

QObject::connect(...)

In ruby this doesn't work. Is there another way?

* It seems to be impossible to reopen predefined Qt/KDE classes to add signals 
and slots to them, even if it is possible to add common methods. For example, 
the following works:

require 'Qt4'

class Qt::PushButton
  def custom_method
    puts "custom method"
  end
end

app = Qt::Application.new []
w = Qt::PushButton.new
w.custom_method

Instead, if I try to add a signal, I get an error when I try to connect to it:

require 'Qt4'

class Qt::PushButton
  signals 'custom_signal()'
end

app = Qt::Application.new []
w = Qt::PushButton.new
w.connect(SIGNAL('custom_signal()')){puts "custom_signal"}

The error message is:

/usr/lib/ruby/site_ruby/1.8/Qt/qtruby4.rb:2706:in `getMetaObject': undefined 
method `name' for nil:NilClass (NoMethodError)
        from /usr/lib/ruby/site_ruby/1.8/Qt/qtruby4.rb:2707:in `getMetaObject'
        from /usr/lib/ruby/site_ruby/1.8/Qt/qtruby4.rb:2740:in `metaObject'
        from /usr/lib/ruby/site_ruby/1.8/Qt/qtruby4.rb:2740:in 
`method_missing'
        from /usr/lib/ruby/site_ruby/1.8/Qt/qtruby4.rb:2740:in `connect'
        from /usr/lib/ruby/site_ruby/1.8/Qt/qtruby4.rb:2740:in 
`signal_connect'
        from prova.rb:9:in `connect'
        from prova.rb:9

The same seems to happen for slots. Again, is this simply a bug, or it simply 
can't be done?

Thanks in advance

Stefano