From: jfn@... (Jeremy Nelson)
Date: 2001-02-13T07:10:03+09:00
Subject: [ruby-talk:10760] How do I love ruby? [Because it's easy to fix things!]

If anyone has read my messages, they have observed that I am in the midst
of a saga of learning both Ruby *and* Tk at the same time.  I should say
that I am thouroughly enjoying this, and programming in Ruby is the most fun
I have had in many, many years!  (And I don't even hate Tk yet! =)

One thing that I did notice about ruby/tk is that there is no parallel
to the focusNext and focusPrev methods as in perl/tk. [1]  I did find the 
'tkmngfocus.rb' file in the ruby/tk library, but those functions do not
seem to do what it is that I was trying to do.  At the very best, I was 
able to get them to return a window path, but not to actually focus on 
that window.

After pondering the circumstances for a while, (and a lot of digging around
trying to learn how Ruby/Tk works), I realized that ruby can retroactively
permit you to extend class definitions.  Thus, whipping up the following
modest functions:

	class TkObject
		def focusNext
			tk_call 'focus', tk_call 'tk_focusNext', @path
		end
		def focusPrev
			tk_call 'focus', tk_call 'tk_focusPrev', @path
		end
	end

and putting this at the top of my source file, permits me to use the
focusNext and focusPrev functions from *any* Tk widget automagically!

The ability to "fix" things as needed on the fly is yet another reason
why Ruby is quickly becoming my favorite language.

Jeremy

[1] My program needs to go to the next entry widget when the user presses
    the KP_Enter key.  <Tab> already does this, but I could not figure out
    how to alias a key to do what <Tab> does, so I arrived at this solution.