How to create Ruby Tk radiobuttons in nested loops - ruby

Question

Using Ruby Tk, I'm wanting to create sets of radio buttons in nested loops: an outer loop for devices (Foo, Bar, Baz), and inner loop for actions on each device (Start, Stop, Pause, Nuke).
Current code:
require 'tk'
device_names = %w/Foo Bar Baz/
action_names = %w/Start Pause Stop Nuke/
button_variables = Array.new(device_names.size)
root = TkRoot.new
foo = bar = nil
device_names.each_with_index do |device_name, i|
TkLabel.new(root) do
text device_name
pack {}
end
action_names.each_with_index do |action_name, j|
TkRadiobutton.new(root) do
text action_name
value j
variable button_variables[i]
pack {}
end
end
end
Tk.mainloop
This produces the 12 radiobuttons, but when I click on any of the 4 Pause buttons, for example, all 4 Pause buttons are set.
Other variations of the code produce the 12 radiobuttons, but all as one set; i.e., only one of the 12 is set at any given time.
What's needed to group these into 3 sets of 4 radiobuttons?
(This code is pared down from a much larger application, which is why it does not make much sense symantically.)

Answer 1

The value passed as variable is the name of a global variable.
The outer loop needs to dynamically define an instance variable, via instance_variable_set:
This code works:
require 'tk'
device_names = %w/Foo Bar Baz/
action_names = %w/Start Pause Stop Nuke/
root = TkRoot.new
device_names.each do |device_name|
TkLabel.new(root) do
text device_name
pack {}
end
instance_variable_set("##{device_name}", nil)
action_names.each do |action_name|
TkRadiobutton.new(root) do
text action_name
value action_name
variable device_name
pack {}
end
end
end
Tk.mainloop