in reply to Indices and inserts in Tk::Text

No, it's not a bug in Tk, but the way the Text widget works...it always adds a newline at the end of text, so you need to strip it when doing indices. A fix for your code is (and notice double quotes around end - 1c) 
my $but2 = $frame->Button(-text => "Replace in the end",
              -command => [\&replace,$text,'16.0',  "end - 1c"  ])
     ->pack(-side => 'left');

[download]
This shows the empty text problem more clearly: 
#!/usr/bin/perl
use warnings;
use strict;
use Tk;

my $mw = MainWindow->new;
my $text = $mw->Text->pack;

my $bFrame = $mw->Frame->pack(qw/-side bottom/);

$bFrame->Button(
   -text => "Check Text",
   -command => sub {
      if ($text->index('end - 1c') == 1) {
         print "Text is empty\n";
      } else {
         print "Text contains data\n";
      }
})->pack(qw/-side left/);

$bFrame->Button(
   -text => "Clear Text",
   -command => sub {
      $text->delete("1.0", 'end');
})->pack(qw/-side left/);

MainLoop;

[download]
I'm not really a human, but I play one on earth Remember How Lucky You Are

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Re^2: Indices and inserts in Tk::Text
by jethro (Monsignor) on Nov 27, 2008 at 19:56 UTC

    Lets call it an intentional bug then. Or at least it is a huge inconsistency. If you change the sub in anna_blacks program to:

    sub replace {
    my ($text,$start_index,$end_index) = @_;
    my $old_data = $text->get($start_index,$end_index);
    print "<$old_data>\n";
    $old_data =~ s/cdefg/12345/g;
    $text->delete($start_index,$end_index);
    $text->insert($start_index,$old_data);
    my $old_data = $text->get('3.0',$end_index);
    print "<$old_data>\n";
    return;
}

    [download]

    ... you can see that the insert started one char too early.

    It could be argued that you should not insert into lines that don't exist (i.e. after the delete of all lines starting from line 16 the location 16.0 doesn't really exist anymore). But then your 'end-1c' solution would be illegal as well, and it only works because the additional \n is confused with the \n of not-existant line 16.

    If TK inserts spurious characters it is its job to make sure that those characters don't get in the way of the programmer.

    PS: Why double quotes? They don't do anything different than a single quote here.

    UPDATE: changed 2 sentences
[reply]
[d/l]
      Oh, you are right about the double quotes not making a difference.

      As far as it being a bug or not, that is left up to you, all I'm saying is that is the way it works. There are alot of complicated interactions in the predefined subs in the Tk::Text module, that break expected behavior when changing or overriding them. I'm sure that if you redine 'end', that somwhere it will break some other method. File a bug report if you want.

      I'm not really a human, but I play one on earth Remember How Lucky You Are
[reply]

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