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

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",
      }
    );
  }
);
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Re^3: Confused by variable scope in Tk::Wizard by Anonymous Monk on Apr 19, 2011 at 01:52 UTC
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); }` [download] 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	[reply] [d/l] [select]

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Re^3: Confused by variable scope in Tk::Wizard
by Anonymous Monk on Apr 19, 2011 at 01:52 UTC

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

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 :)

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