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Ruby Programming
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Getting Widget Data

We can get information back from widgets with callbacks and by binding variables.

Callbacks are very easy to set up. The command option (shown in the TkButton call in the example that follows) takes a Proc object, which will be called when the callback fires. Here we use Kernel::proc to convert the {exit} block to a Proc.

TkButton.new(bottom) {
  text "Ok"
  command proc { p mycheck.value; exit }
  pack('side'=>'left', 'padx'=>10, 'pady'=>10)
}

We can also bind a Ruby variable to a Tk widget's value using a TkVariable proxy. We show this in the following example. Notice how the TkCheckButton is set up; the documentation says that the variable option takes a var reference as an argument. For this, we create a Tk variable reference using TkVariable.new. Accessing mycheck.value will return the string ``0'' or ``1'' depending on whether the checkbox is checked. You can use the same mechanism for anything that supports a var reference, such as radio buttons and text fields.

mycheck = TkVariable.new

TkCheckButton.new(top) {   variable mycheck   pack('padx'=>5, 'pady'=>5, 'side' => 'left') }
Ruby Programming
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