Ruby TkButton won't run proc - ruby

Question

I have a ruby program that uses the TK gui package and I am having trouble with TkButton, specifically the command part. I am trying to run a method that's in the same class when the button is clicked. My code is below. I'm very new to Ruby but not programming in general. When the button is clicked in the gui I get an Application error that says "Error: NameError: unknown option..." where it identifies the method call in the button as the error cause. Can someone explain what I'm doing wrong? I'm using RubyMine to develop.
Code:
require 'tk'
require 'test/unit'
require_relative 'calc'
require_relative 'calcTest'
class CalcUIK
def test_add
calc = Calc.new
expected = Calc.add tk6.get().to_i,tk6.get().to_i
tk8['textvariable'] = 'Result: ' + expected
end
hello = TkRoot.new do
title "Hello World"
# the min size of window
minsize(400,400)
end
tk1 = TkLabel.new(hello) do
text 'Super Calculator'
foreground 'red'
pack { padx 15; pady 15; side 'left'}
end
tk5 = TkLabel.new(hello) do
text 'Enter two numbers to math'
foreground 'blue'
pack { padx 15; pady 15; side 'left'}
end
tk6 = TkEntry.new(hello) do
foreground 'blue'
pack { padx 15; pady 15; side 'left'}
end
tk7 = TkEntry.new(hello) do
foreground 'blue'
pack { padx 15; pady 15; side 'left'}
end
tk8 = TkLabel.new(hello) do
textvariable
foreground 'blue'
pack { padx 15; pady 15; side 'left'}
end
tk2 = TkButton.new(hello){
text 'Add'
command (proc {self.test_add})
pack('padx'=>'20')
pack('side'=>'left')
}
end
Tk.mainloop
PS I know that this code is kind of dumb but it is just a dummy program to set some more important things up. The issue I need to resolve is why the button click is not executing the test_add method. Thanks.

Answer 1

You've defined an instance method on your class called test_add, but in the context in which your "Add" button is defined, self refers to the class CalcUIK. Edit - now that I think about it, I think since self occurs within a block given to TkButton.new, self refers to the new instance of TkButton, which is trying to receive the test_add method, but doesn't recognize it as a valid option. Define the proc as proc { CalcUIK.new.test_add } to generate a new instance that will run the method.
I would also recommend moving all of the TkRoot, TkButton, etc. calls either outside the class entirely, or move them into an initialize method on CalcUIK. Right now, they are run as the class is evaluated, but it's very unusual to have code that is unrelated to the class executed within the context of the class definition.