From: Morton Goldberg <m_goldberg@...>
Date: 2008-02-23T14:19:53+09:00
Subject: Re: Ruby/Tk

On Feb 22, 2008, at 10:07 PM, Isaac Toothyxdip wrote:

> This is something else i tried but of course it didnt work
>
> require 'tk'
>
> hello = TkRoot.new do
>   title "Hello World"
>   # the min size of window
>   minsize(400,400)
> end
>
> number = 1
>
> def addnumber
>   @text.value = number
> end
>
> @text = TkVariable.new
> lbl = TkEntry.new('textvariable' => @text) { justify 'center'
>   pack('padx'=>5, 'pady'=>5, 'side' => 'top') }
> TkButton.new() {
>   text "Add One"
>   command proc {addnumber}
>   pack('side'=>'right', 'padx'=>10, 'pady'=>10)
> }
> Tk.mainloop


It didn't work mainly because you are confused about how Ruby scopes  
variables. My example defines a new class for good reason -- to make  
sure the variables I use are visible where and when I need them.

<code>
require 'tk'

class Example
    def initialize
       @number = TkVariable.new(1)
       root = Tk.root
       root.title('Ruby/Tk Example')
       # @entry = TkLabel.new(root) {
       #    width 10
       #    borderwidth 1
       #    relief :solid
       #    pack(:pady => 10)
       # }
       @entry = TkEntry.new(root) {
          width 10
          justify :center
          pack(:pady => 10)
       }
       @entry.textvariable = @number
       @btn = TkButton.new(root) {
          text "Add One"
          pack(:pady => 10)
       }
       @btn.command = lambda { action }
       # Set initial window geometry; i.e., size and placement.
       win_w, win_h, win_y = 200, 85, 50
       win_x = (root.winfo_screenwidth - win_w) / 2
       root.geometry("#{win_w}x#{win_h}+#{win_x}+#{win_y}")
       # Set resize permissions.
       root.resizable(false, false)
       # Make Cmnd+Q work as expected on OS X.
       if RUBY_PLATFORM =~ /darwin/
          root.bind('Command-q') { root.destroy }
       end
       Tk.mainloop
    end

    def action
       @number.numeric += 1
    end
end

Example.new
</code>

The commented-out code will also work if you uncomment it and comment  
out the @entry = TkEntry { ... } code instead. This is because  
TkEntry is a direct subclass of TkLabel and inherits its textvariable  
property from TkLabel. The difference is that you can edit the  
numbers when a TkEntry object is used. For instance, if you edit a  
displayed number to 42, when you click on the button, the next number  
will be 43.

Regards, Morton