Re^2: Confused by variable scope in Tk::Wizard

[rgcosma]

Thank you very much, the example does work. I do have to admit though that I don't understand why.. the syntax around this segment gives me a headache:

$wiz->addPage (
  sub {
    $wiz->_text_frame(
      {
        -title => 'Partitioning',
        -boxedtext => "/mirror/inifiles/partition.$oschoice",
      }
    );
  }
);

[Anonymous Monk]

Here is the exact same thing only written more verbosely

{
    my $Aspirin = sub {
        return $wiz->_text_frame(
            {
                -title     => 'Partitioning',
                -boxedtext => "/mirror/inifiles/partition.$oschoice",
            }
        );
    };
    $wiz->addPage($Aspirin);
}

I suspect you're having trouble with closures

In my original program, this unnamed subroutine, this anonymous subroutine, whose reference is now stored in $Aspirin, refers to two variables outside its scope. Namely $oschoice and $wiz, which are not declared (my) within $Aspirin. This makes $Aspirin a closure.

Each time you call this subroutine, $Aspirin->(); it calls _text_frame with the current value of $oschoice

So if $oschoice="Lin" then $Aspirin->() returns a frame with /mirror/inifiles/partition.Lin

Next you change $oschoice="Win" and then $Aspirin->() returns a frame with /mirror/inifiles/partition.Win

The first step in the wizard edits $oschoice, then when you click next, the wizard invokes $Aspirin , which returns a new frame using the current value of $oschoice

If you click the back button and select a different OS, and click next again, the wizard will call $Aspirin again

More on closures, hopefully easier to understand :) oh and no wizards or witches :)

• Closure Explanation
• Closures Explained
• closures
• http://perl.apache.org/docs/general/perl_reference/perl_reference.html#Understanding_Closures____the_Easy_Way
• Tutorials: Closure on Closures
• Achieving Closure - Perl.com