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Ruby Programming
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Setting/Getting Options Dynamically

In addition to setting a widget's options when it's created, you can reconfigure a widget while it's running. Every widget supports the configure method, which takes a Hash or a code block in the same manner as new. We can modify the first example to change the label text in response to a button press:

lbl = TkLabel.new(top) { justify 'center'
  text    'Hello, World!';
  pack('padx'=>5, 'pady'=>5, 'side' => 'top') }
TkButton.new(top) {
  text "Cancel"
  command proc { lbl.configure('text'=>"Goodbye, Cruel World!") }
  pack('side'=>'right', 'padx'=>10, 'pady'=>10)
}

Now when the Cancel button is pressed, the text in the label will change immediately from ``Hello, World!'' to ``Goodbye, Cruel World!''

You can also query widgets for particular option values using cget:

require 'tk'
b = TkButton.new {
  text     "OK"
  justify  'left'
  border   5
}
b.cget('text') "OK"
b.cget('justify') "left"
b.cget('border') 5

Ruby Programming
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