I'm working on a Tk project that includes the ability to edit a set of filters, much like email filters. I've come up with a scheme that uses two HList widgets to manage this.

The user interaction works nicely, but I've discovered that I've got some memory issues. Every time I select a new rule for editing, I gobble up about 110 K of ram.

Before I go into much more detail, my questions are:

Here's a gross little ASCII picture of the interface: 

+--------------------------------+
| [ ] A Rule                   X |
| [X] A Different Rule         X |
|  +                             |
+--------------------------------+
 
Name _____________________
Run if [ANY =] conditions:
+--------------------------------+
|[FIELD1 =] [  > =] __________ X |
|[FIELD2 =] [  < =] __________ X |
|[FIELD3 =] [ is =] [ value =] X |
+--------------------------------+

Legend:
[FOO =] is meant to represent an Optionmenu
The X and + are buttons for adding or deleting items
_____ are Entry widgets
The borders denote my HList widgets.

[download]

How it works

When a user selects a rule in the top HList, it is displayed in the bottom HList. The I copy the rule into my "working copy" aka my object's rule attribute. The Rule and Clause objects are basic Class::Struct based objects. Then I clean out the bottom HList by explicitly destroying the widgets in each item, and delete each entry. Then I create new entries and items and populate them with new widgets. A lot of widgets are created and destroyed in this process, but the only other option I can see is creating a pool of widgets and parceling them out or creating new ones as needed--a task I'd rather not manage.

sub EditRule {
    my $self = shift;
    my $rule = shift || 'NO_COPY';

    if ( $rule ne 'NO_COPY') {
        
        $rule->copy($self->original_rule);
        $rule->copy($self->rule);

    }

    
    # This is my HList widget
    my $clause_list = $self->clause_list;

    # Here we remove all items from the HList.
    foreach my $path ( $clause_list->info('children') ) {
        print "Deleting $path\n";
        foreach (0..3) {
            next unless $clause_list->item('exists', $path, $_);

            my $w = $clause_list->item('cget', $path, $_, '-widget');

            # This is testing code where I try explicitly clearing out
+ bits the widgets I use.
            # It could be refined by writing an arg list to an array a
+nd passing it to a generic $w->configure call.
            if ( ref $w eq 'Tk::Button' ) {
                print "\tCleaning button\n";
                $w->configure(
                    '-command'=> undef,
                    -textvariable => undef
                ); 
            } elsif ( ref $w eq 'Tk::Optionmenu' ) {
                print "\tCleaning Optionmenu\n";
                $w->options($NULL_OPTS);
                $w->configure(
                    '-command'=> undef, 
                    -textvariable => undef,
                ); 
            } elsif ( ref $w eq 'Tk::Entry' ) {
                print "\tCleaning Entry\n";
                $w->configure(
                    -textvariable => undef,
                ); 
            }

            $w->DESTROY;
        }
        $clause_list->delete('entry', $path);
    }

    # This gets a list of conditions or clauses for the rule
    # Clause is another Class::Struct based object.
    my $clauses = $self->rule->clauses;
    
    # Here I make a new HList item to house the NEW CLAUSE button.
    # methods called _W_blah_blah return a widget.
    $clause_list->add('new_clause');
    $clause_list->itemCreate('new_clause',0,
        -itemtype => 'window',
        -widget   => $self->_W_new_clause(),
    );


    # Here I add a new entry for each clause in the rule.
    foreach my $i ( 0..$#{$clauses} ) {
        $self->DisplayClause($i);
    }

    $self->join_op->configure( 
            -state => 'normal',
    );

}   # END EditRule -----------------------------------------

sub DisplayClause {
    my $self = shift;
    my $i = shift;    # Clause index

    my $clause_list = $self->clause_list; # Get my HList widget
    my $clause = $self->rule->clauses->[$i]; # Get the clause to displ
+ay.

    # I know that no item exists at HList path $i.
    $clause_list->add($i, -before=>'new_clause');

    # Create the Tix display items.
    # _W_foobar returns a widget.
    # different field values have different operator and value widgets
+.
    $clause_list->itemCreate($i, 0, 
        -itemtype => 'window', 
        -widget   => $self->_W_select_field($clause, $i),
    );
    $clause_list->itemCreate($i, 1, 
        -itemtype => 'window', 
        -widget   => $self->_W_select_op($clause),
    );
    $clause_list->itemCreate($i, 2, 
        -itemtype => 'window', 
        -widget   => $self->_W_select_value($clause),
    );
    $clause_list->itemCreate($i,3,
        -itemtype => 'window',
        -widget   => $self->_W_delete_clause($i),
    );

}

[download]

Any ideas? Comments? Rebukes for my foolishness?


TGI says moo

In reply to Tk, HLists and memory leakage by TGI

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