Forum: Ruby Tk and instance variables (pickaxe book Ed 2, p260)

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John M. (Guest)
on 2006-01-14 23:56
(Received via mailing list)
Chaps,

There's a small section of code from the second edition of the pickaxe
book on p260.

require 'tk'

image1 = TkPhotoImage.new {file "img1.gif" }
image2 = TkPhotoImage.new {file "img2.gif" }

b = TkButton.new(@root) do #  <---- This line
 # more code
 # not shown for sake of brevity
end
# more code
# more code

Am I right in saying that the line that creates the new button has an
instance variable that will be used to define the main root "container"?
David V. (Guest)
on 2006-01-21 16:40
(Received via mailing list)
On Sat, 14 Jan 2006 22:54:58 +0100, John M. 
<removed_email_address@domain.invalid>
wrote:

> b = TkButton.new(@root) do #  <---- This line
>  # more code
>  # not shown for sake of brevity
> end
> # more code
> # more code
> Am I right in saying that the line that creates the new button has an
> instance variable that will be used to define the main root "container"?
>


If my (horrible) memory of the 15 minutes I've worked in Tk serves me
right for a change, there's a

@root = TkRoot.new

missing there somewhere. All other widgets should require a parent
container parameter for their constructor. TkRoot serves as the toplevel
container for a Tk interface and contains some plumbing related to the
event loop and such.

David V.
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