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perl/tk changing button commands

by Anonymous Monk
on Apr 22, 2003 at 17:12 UTC ( #252319=perlquestion: print w/ replies, xml ) Need Help??
Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

i have a perl/tk program witch is just a text widget, and a button, and i want the text to change everytime i click the button. so i need to be able to change the command of the button each time it is clicked, does anybody know how to do this? here is the code:
#!/usr/bin/perl use strict; use warnings; use Tk; sub one; my $main = MainWindow->new; my $label1 = $main->Text ( '-width'=>'50' )->pack; my $button = $main->Button ( -text=>'next', -command=>sub{one} )->pack; MainLoop; sub one { my $talk2="number1"; my $talk="this text will be changing after every click of the butt +on."; $label1 -> insert('1.0',"$talk"); my $button = $main->Button(-text=>'next',-command=>sub{two})->pack +; } sub two { # change the text box again }

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Re: perl/tk changing button commands
by Improv (Pilgrim) on Apr 22, 2003 at 17:30 UTC
    Some comments
    • I doubt you really mean to be adding all those new buttons everytime you click 'next', right? You might want to read up about how the Tk event loop works.
    • You had the syntax for -command incorrect. You either pass it an anonymous subroutine (as in the $button2 example below) or a code reference, with \&
    See below for corrected code.
Re: perl/tk changing button commands
by hiseldl (Priest) on Apr 22, 2003 at 21:38 UTC

    If you want to change the action of the button every time it is pressed, then you need to leave out the -command switch and bind the 'ButtonPress' action later. This will allow you to re-bind the action once you have pressed the button. Here's an example:

    #!/usr/bin/perl use strict; use warnings; use Tk; my $main = MainWindow->new; my $text = $main->Scrolled('Text', -width=>'50' )->pack; my $button = $main->Button(-text=>'next', )->pack; $button->bind('<ButtonPress>', \&one); MainLoop; sub one { my $talk="One! Click for two.\n"; $text -> insert('1.0',"$talk"); $button->bind('<ButtonPress>', \&two); } sub two { my $talk="One! Click for three.\n"; $text -> insert('1.0',"$talk"); $button->bind('<ButtonPress>', \&three); } sub three { my $talk="One! Click for one.\n"; $text -> delete('1.0', 'end'); $text -> insert('1.0',"$talk"); $button->bind('<ButtonPress>', \&one); }

    Cheers!

    --
    hiseldl
    What time is it? It's Camel Time!

Re: perl/tk changing button commands
by kelan (Deacon) on Apr 23, 2003 at 13:56 UTC

    How about just having an array that holds whatever pieces of text you want and looping through it. (Untested)

    #!/usr/bin/perl use strict; use warnings; use Tk; my $main = MainWindow->new; my $label1 = $main->Text( -width => 50 )->pack; my $count = 0; my @texts = ( "This is the first piece.\n", "This is the second.\n", "This is the third.\n", "etc...\n", ); my $button = $main->Button( -text => "Next", -command => sub { $label1->insert('1.0', $texts[$count++]); } )->pack; MainLoop;

    kelan


    Perl6 Grammar Student

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