1require 'tk'
2
3v = TkVariable.new(0)
4l = TkLabel.new(:textvariable=>v).pack(:pady=>[1, 10])
5
6a = TkButton.new(:text=>"button A :: proc{p ['AAA', v.value]}").pack(:fill=>:x, :pady=>[1, 15], :padx=>15)
7a.command{p ['AAA', v.value]}
8
9TkLabel.new(:text=>'Callback of the button B returns LIFO order').pack
10b = TkButton.new(:text=>"button B :: proc{n = v.value; p ['B:start', n]; Tk.sleep(10000); p ['B:end', n]}").pack(:fill=>:x, :pady=>[1, 15], :padx=>15)
11b.command{n = v.value; p ['B:start', n]; Tk.sleep(10000); p ['B:end', n]}
12
13TkLabel.new(:text=>'Callback of the button C returns FIFO order').pack
14c = TkButton.new(:text=>"button C :: proc{n = v.value; Thread.new{p ['C:start', n]; Tk.sleep(10000); p ['C:end', n]}}").pack(:fill=>:x, :pady=>[1, 15], :padx=>15)
15c.command{n = v.value; Thread.new{p ['C:start', n]; Tk.sleep(10000); p ['C:end', n]}}
16
17TkLabel.new(:text=>'Callback of the button D blocks eventloop (no respond to event)').pack
18d = TkButton.new(:text=>"button D :: proc{n = v.value; p ['D:start', n]; sleep(10); p ['D:end', n]}").pack(:fill=>:x, :pady=>[1,15], :padx=>15)
19d.command{n = v.value; p ['D:start', n]; sleep(10); p ['D:end', n]}
20
21TkLabel.new(:text=>'Callback of the button E is another way to avoid eventloop blocking').pack
22e = TkButton.new(:text=>"button E :: proc{n = v.value; Thread.new{p ['D:start', n]; sleep(10); p ['D:end', n]}}").pack(:fill=>:x, :pady=>[1,15], :padx=>15)
23e.command{n = v.value; Thread.new{p ['D:start', n]; sleep(10); p ['D:end', n]}}
24
25TkButton.new(:text=>'QUIT', :command=>proc{exit}).pack
26
27TkTimer.new(500, -1){v.numeric += 1}.start
28
29Tk.mainloop
30