Re: [ruby-fltk-users] Fltk::ListBox and Fltk::HoldBrowser

[Takaaki T. <tt...@kt...>]

At Sun, 30 Sep 2001 16:48:18 -0400,
Kent Dahl <ke...@st...> wrote:
> ...I still get b==nil. Its not an immediate problem, as I can get the
> data thru the browser object, but since most Fltk callbacks use the
> idiom of a widget pointer and a void pointer as arguments in C++, this
> caught me by surprise. 

If you'd like to get non-nil value, give the data like this:

@transactionlist.callback(somedata){ ... }

> Reading /ruby-fltk/doc/en/guide.txtand especially 3.2 seems to be
> somewhat misleading on this subject, as it states that only the data
> should be passed. I'm assuming it should say that the widget itself and
> the data will be passed. (Or is this changing?)

Here is a part of FLTK manual:

  Each line contains a null-terminated string of text and a void * data pointer.
  The text string is displayed, the void * pointer can be used by the callbacks
  to reference the object the text describes.

If I don't misunderstand, I think this description mention
something like "a.data(a.value)" in your code,
and the void * pointer (= "a.data(a.value)") *can* be used
in the callback block.

  @transactionlist.callback do |a,b| 
    puts a.value.to_s + ":" + a.data(a.value).to_s + ";" + b
  end

But I don't be assure of my thought.
-- 
Takaaki Tateishi <tt...@kt...>