From: David Tran <email55555@...>
Date: 2005-08-02T06:53:52+09:00
Subject: Tk - Ruby/Tk core library design questions

I forgot which old version is, on that old version, the widget.pack
method always returns nil.
So people have to write something like:

b = TkButton.new {
  pack
}

Now the pack returns self, what's great improvement, so we can write
something like:
b = TkButton.new.pack.command { puts "Hello" }

Now, my ruby version is : ruby 1.8.2 (2004-12-25) [i386-mswin32]
and my Tcl/Tk version is : 8.4
I have some Ruby/Tk design questions :

(1) Layout Manager:
there are:
widget.pack ;  TkPack.pack ; Tk.pack
widget.grid ; TkGrid.grid ; Tk.grid
widget.place ; TkPlace.place
methods, why there is no Tk.place method ?
This seems inconsistent for me.

(2) Since we try to wrap Tcl/Tk on OO, why some Tcl commands are not
treat like options ?
Most options have getter and setter method, there are many way to do
it, for example:
# setter
button.bg = :red
button.bg(:red)
button.configure(:bg, :red)
# getter
puts button.bg
puts button.cget(:bg)

Now, for example, root.title and root.iconbitmap ... etc are command
but not options on Tcl/Tk language.
But, I feel this will be nice if we "wrap" them like options, so we
can write something like:
TkRoot.new(:title=>'Hello')  or
TkButton.new(:text=>'set title').command { Tk.root.title = "some title" }
For me, it seems title is just like an option for TkRoot.
(But in current version, it is not, so I cannot use :title=>... or
root.title = ... syntax )

(3)
require 'tk'
c = TkCanvas.new.pack
TkcRectangle.new(c, 10, 10, 50, 50)
Tk.mainloop

The above code works fine, but if I rewrite it to become

require 'tk'
TkcRectangle.new(TkCanvas.new.pack, 10, 10, 50, 50)
Tk.mainloop

I got this error: uninitialized constant TkcRectangle (NameError)

Rewrite it again like:

require 'tk'
TkCanvas
TkcRectangle.new(TkCanvas.new.pack, 10, 10, 50, 50)
Tk.mainloop

It works fine again.

So, what's going wrong with:
require 'tk' ; TkcRectangle.new(TkCanvas.new.pack, 10, 10, 50, 50) ; Tk.mainloop
Why should I reference TkCanvas ( at least class ) first ?

Thank you.