merrymonk has asked for the wisdom of the Perl Monks concerning the following question:

On the website http://search.cpan.org/~srezic/Tk-804.028/pod/Balloon.pod
I found the following to attach balloons (tooltips) to individual options on a menu.
# Balloon attached to entries in a menu widget:
$b->attach($menu, -state => 'status',
-msg => 'first menu entry', </br> 'second menu entry', </br> ... </br> ,
);
I tried to use this as shown in the Perl below.
use Tk;
use Tk::Balloon;
use strict "vars";
my ($mw);   
my (%tooltip_mes, %tooltip_status_mes, %balloon_wg, %wg, @local_option
+s, @mes_options, @sta_options, $option_res);
$mw = MainWindow->new(-title => "Simple example");
$local_options[0] = 'Option 1';
$local_options[1] = 'Option 2';
$local_options[2] = 'Option 3';
$local_options[3] = 'Option 4';

$mes_options[0] = "tooltip 1/nOption A";
$mes_options[1] = "tooltip 2/nOption B";
$mes_options[2] = "tooltip 3/nOption C";
$mes_options[3] = "tooltip 4/nOption D";
$wg{APullDown_Option} = $mw->Optionmenu(
                -textvariable     => \$option_res,
                -state        => 'normal',
                 -options      => [@local_options])->pack;
# line that fails
$balloon_wg{pulldown}->attach($wg{APullDown_Option}, -msg => [@mes_opt
+ions]);
MainLoop;

[download]
Sadly this fails with the message
Can't call method "attach" on an undefined value at line nn.
This is the line where I try to attach the balloon to the pull down menu. Without this line the pull down menu can be seen.
Does anyone know how to solve this?
Also, can messages to the status area be associated with each option of the pull down menu?

Replies are listed 'Best First'.
Re: Balloon and menus options
by almut (Canon) on Dec 07, 2009 at 13:11 UTC

    You don't seem to assign anything to the hash entry $balloon_wg{pulldown} (or to the hash %balloon_wg at all) anywhere in the script...

[reply]
[d/l]
[select]
      Thanks to you both. Absolutely correct!
      Therefore I added the following.
      $wg{Status_Label} = $mw->Label(-borderwidth => 2, -relief => 'groove')
  ->pack(-side => 'bottom');
$balloon_wg{pulldown} = $mw->Balloon(-statusbar => $wg{Status_Label});
$balloon_wg{pulldown}->attach($wg{APullDown_Option}, -msg => [@mes_opt
+ions]);
# lines A
#$balloon_wg{pulldown}->attach($wg{APullDown_Option}, -state => 'ballo
+on',
#                            -msg => ['A1', 'B2','C3', 'D4']);
# line B
#$balloon_wg{pulldown}->attach($wg{APullDown_Option}, -msg => [@mes_op
+tions]);

      [download]
      As you can see there are two options , two lines for A and one for B
      For both I got messages of the form
      Malformed UTF-8 character (unexpected continuation byte 0xb6, with no preceding start byte) in null operation at ….site/lib/Tk.pm line 406.
      How can I cure this?
[reply]
[d/l]

        I can replicate the problem (but mind you, I'm no Tk-wiz either).  I.e. with the following simple test script 

        #!/usr/local/bin/perl

use strict;
use warnings;
use Tk;
use Tk::Balloon;

my $mw = MainWindow->new();
$mw->title('Simple example');

my $status  = $mw->Label(
                  -width => 20,
                  -relief => 'groove',
              )->pack();

my $balloon = $mw->Balloon(-statusbar => $status);

my $menu    = $mw->Optionmenu(
                  -textvariable => \my $res,
                  -options      => [qw(A B C D)],
              )->pack();

$balloon->attach(
    $menu,
    -msg => [qw(a b c d)],

    #-msg => 'foo',
    # this works, but you get the same msg for all menu entries, of co
+urse
);

MainLoop;

        [download]

        it seems that random strings from memory are being displayed as tooltip texts, which would also explain the "Malformed UTF-8 character" messages (because a random sequence of bytes is typically not well-formed UTF-8).

        Apparently, the -msg => [...] doesn't work as advertised  (a simple scalar "works", but that of course doesn't make much sense for a menu...).

        (Perl 5.8.4, $Tk::VERSION: 804.027 — I don't have anything more recent on this box)

[reply]
[d/l]
[select]
        How can I cure this?

        it would help if you could come up with a small example that gives the error, and the exact platform you are on..... it now sounds like a different problem, probably unicode related..... and you probably should use strict completely, not just strict 'vars'

        I'm not really a human, but I play one on earth.
        Old Perl Programmer Haiku
[reply]
[reply]
Re: Balloon and menus options
by Anonymous Monk on Dec 07, 2009 at 13:11 UTC
    Can't call method "attach" on an undefined value at line nn. This is the line where I try to attach the balloon to the pull down menu. Without this line the pull down menu can be seen. Does anyone know how to solve this?

    Define $balloon_wg{pulldown}

[reply]

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