From: nagai@...
Date: 2001-10-17T16:16:17+09:00
Subject: [ruby-talk:22663] Re: Ruby/Tk  How to set a text mark

Hi, 

From: Albert Wagner <alwagner@tcac.net>
Subject: [ruby-talk:22660] Ruby/Tk  How to set a text mark
Date: Wed, 17 Oct 2001 10:58:59 +0900
Message-ID: <20011017015718.OQWU18411.io@there>
alwagner> Can you help me to set a text mark?

A text index must be String. 
If you give a index 'line.char' as Float, 
sometimes Ruby/Tk misunderstands it.
( for example, 2.10 ==> '2.1' )

If you want to use TkTextMark with modifires, 
you will have to use TkTextMark#id method. 
The method returns the mark name on Tk. 
By using the name, you must generate index description.

For example, 
------------------------------------------------
t = TkText.new.pack
t.insert('1.0', "0123456789\nABCDEFGHIJKLMN\nabcdefghijklmn\n")
m1 = TkTextMark.new(t, '1.end')
m2 = TkTextMark.new(t, '2.10')
m3 = TkTextMark.new(t, '@20,40')         # coordinate on the text widget
p t.mark_names                           #=> return array of TkTextMark objects
p t.index(m1)                            #=> "1.10"
p t.index(m3)                            #=> for example, "3.2"
p t.index(m2.id + ' lineend')            #=> "2.14"
p t.index(m2.id + ' + 1 lines - 5 chars')#=> "3.5"
p t.compare(m1, '<', m2)                 #=> true
p t.compare(m1, '>', m2)                 #=> false
p t.get(m1,m2)                           #=> "\nABCDEFGHIJ"
p t.get(m2,m1)                           #=> ""
m1.set(m1.id + '+1chars')
p t.index(m1)                            #=> "2.0"
p t.get(m1,m2)                           #=> "ABCDEFGHIJ"
------------------------------------------------

And, I found bad implements in TkTextMark class. 
Current definitions of TkTextMark#next and TkTextMark#previous are
------------------------------------------------
  def next(index)
    @t.tagid2obj(tk_call(@t.path, 'mark', 'next', index))
  end

  def previous(index)
    @t.tagid2obj(tk_call(@t.path, 'mark', 'previous', index))
  end
------------------------------------------------
These should be followings. 
------------------------------------------------
  def next
    @t.tagid2obj(tk_call(@t.path, 'mark', 'next', @id))
  end

  def previous
    @t.tagid2obj(tk_call(@t.path, 'mark', 'previous', @id))
  end
------------------------------------------------
-- 
                                  Hidetoshi NAGAI (nagai@ai.kyutech.ac.jp)