in reply to Clearing anonymous Tk widgets

To properly closure you should write 
my $goner = $_;
...
sub { delete $runtime{$goner} }

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Re^2: Clearing anonymous Tk widgets
by murrayn (Sexton) on Aug 31, 2012 at 10:03 UTC
    I did consider that but I don't know the name of $goner in advance. There might be one line in the input file or there might be 50. So what I'm trying to achieve is a loop scanning all lines in the input file (they are loaded into a hash by XML::Simple) then building an entry in a Tk GUI window for each line. There are three columns: keyword (as a read only Label), value (r/w as an Entry) and a delete button. The delete button should do two things: remove the entry from the hash with key=keyword and remove (destroy?) the row in the GUI window.
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      Play with this 

      #!/usr/bin/perl --
use strict; use warnings;
use Tk;
use Tk::WidgetDump;
use Tk::ObjScanner;
my %ons;
my $mw = tkinit();
for (1 .. 3) {
    my $goner = $_;
    $ons{$_} = $mw->Button(
        -text => "B $_",
        -command => sub {
            delete($ons{$goner})->destroy; ## this works, proper closu
+re
#~             delete($ons{$_})->destroy; ## this doesnt, $_ is alias
        }
    )->pack;
}
$mw->WidgetDump; ## before scan_object
Tk::ObjScanner::scan_object( { mw => $mw, ons => \%ons } ); ## after W
+idgetDump
MainLoop();

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[reply]
[d/l]
        That looks promising. I'll have a play over the next few days (it's Father's Day in Aus tomorrow - there'd be trouble if I was messing with Perl code then!). I was starting to think I'd need an array of Tk Frames and go destroying them but this looks more elegant. Thanks. I'll let you know how it goes.
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      I did consider that but I don't know the name of $goner in advance.

      Yes you do, its $_, its the keys of %runtime -- if thats not the case, you'll have to restate your question

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        Unless I've done something silly (highly plausible explanation!), I'm not seeing evidence to support that theory. $_ is the value of the key when I build the line in the GUI window and it displays exactly as I'd expect it to and when I put a button on the line saying delete $runtime{$_} it works the first time then objects the second time (makes sense too - the delete worked, so there's nothing there now). So now I want to remove the line from the GUI and I don't have a Tk widget name to destroy.
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