[Kde-bindings] QtRuby section in my book

[Richard Dale]

On Wednesday 05 April 2006 20:47, Jason D. Clinton wrote:
> Hello list;
>
> I've been lurking for quite some time but I finally have something to
> say. I have a section in my upcoming book on using QtRuby for RAD. The
> book is a 'quick reference/pocket reference' style of book called Ruby
> Phrasebook (it's up on Amazon.com). Anyway, it covers Qt4 since that's
> the first release that's GPL for all platforms. Below I have a "Hello
> World" example that I wanted to run by you guys: see any major problems
> with my approach WRT Qt4? There's no documentation out there, yet ...
Another book is good news!

>
> require 'Qt'
>
> app = Qt::Application.new ARGV
>
> class MyDialog < Qt::Widget
>   slots 'button_clicked()'
>
>   def initialize(parent=nil)
>     super(parent)
>
>     @vgroup = Qt::VBoxLayout.new
>     @button = Qt::PushButton.new "Hello World!"
>     @edit   = Qt::LineEdit.new "Hello?"
>
>     @vgroup.addWidget @button
>     @vgroup.addWidget @edit
>
>     connect @button, SIGNAL('clicked()'), self,
>             SLOT('button_clicked()')
>
>     self.setLayout @vgroup
>   end
>
>   def button_clicked()
>     @edit.text = 'Hello! Hello!'
>   end
> end
>
> window = MyDialog.new
> window.show
>
> app.exec
It looks fine to me. I prefer to pass widgets in a block to a layout 
constructor like this:

    @vgroup = Qt::VBoxLayout.new do |v|
        @button = Qt::PushButton.new "Hello World!"
        @edit = Qt::LineEdit.new "Hello?"
        v.addWidget @button
        v.addWidget @edit
    end

And, rather than:
 self.setLayout @vgroup

Either:
  self.layout = @vgroup

Or:
  setLayout @vgroup

Note that you don't need to keep widgets in instance variables if they aren't 
needed once they are installed in a layout. They won't be garbage collected 
if they have a Qt::Widget parent in the Qt::Object heirarchy. So this is 
fine:

    self.layout = Qt::VBoxLayout.new do |v|
        @button = Qt::PushButton.new "Hello World!"
        @edit = Qt::LineEdit.new "Hello?"
        v.addWidget @button
        v.addWidget @edit
    end

On Wednesday 05 April 2006 20:58, Caleb Tennis wrote:
> I think making sure you specify the parent is probably more Qtish:
>
> @button = Qt::PushButton.new("Hello World!", self)
Once the layout is added to the widget, the layout and its widgets are 
children of MyWidget, so you don't really need to do this:

p @button.parent
#<MyDialog:0x3009fcb8 objectName="", x=256, y=230, width=512, height=307>

p self.layout
#<Qt::VBoxLayout:0x3009f6d0 objectName="">

p self.layout.parent
#<MyDialog:0x3009fcb8 objectName="", x=256, y=230, width=512, height=307>

-- Richard