Using the array-ref style of -command is tricky and has limited usefulness, so I'll show you how to do it using an Entry with -textvariable, and using a Button -command with a real sub.

First, when using -textvariable, you want to give a reference to the variable, like so:

my $original_x = 3;

my $user_x = $f1->Entry( -textvariable => \$original_x )->pack;
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Then, whenever $original_x is tested/printed/etc., it contains whatever is currently in the entry box.

Here's a good way to use -command:

$mw->Button( -command => \&print_entries )->pack;

sub print_entries
{
    my $val = $user_x->cget('-text');
    print "$val\n";
}
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The salient facts are these:

1. You should call cget on '-text', not '-textvariable'.
2. The call to cget should be "delayed" until the time the button is pressed, not when it is created. In your form, cget was being called at creation time.

sub print_entries
{
    my $var_ref = $user_x->cget('-textvariable');
    my $val = $$var_ref;
    print "$val\n";
}
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sub print_entries
{
    print "$original_x\n";
}
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Thank you, jdporter for a right solution! I was trying to use @_ in the sub and not getting what I thought I would. I was passing variables to the sub because, coming from another language, I thought scope would be an issue referencing the variables that were modified in a different block. Thanks!

Cheers!
--p



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Don't worry about people stealing your ideas. If your ideas are any good, you'll have to ram them down people's throats.

-Howard Aiken

I believe that you need to pass a reference to a (Update: Scalar) variable into the -textvariable parameter for an entry widget.

use Tk;
require Tk::Entry;
require Tk::Button;

my $mw = MainWindow->new();

my($var1, $var2) = ('val1', 'val2');

my $entry1 = $mw->Entry(-textvariable=> \$var1)->pack();

my $entry2 = $mw->Entry(-textvariable => $var2)->pack();

my $but = $mw->Button(-text=>'print', -command=> sub{print "$var1, $va
+r2\n"; } )->pack();

MainLoop;

__END__
# Output upon pressing print after changeing both entry widget's:

entry1, val2
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Update: Please note that I intentioally left off the backslash on $val2 to demonstrate the different behavior when passing a simple value rather than a scalar reference.

When you create a PerlTk callback that will take arguments, using the [] syntax, the Tk::callbacks documentation says:

the contents of the [] are evaluated by perl when the callback is created

Therefore, your code,

$mw->Button (
  -command => [\&print_entries, $user_x->get(), $original_y],
);
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my $command_sub;
{
  my $x_at_time_of_sub_definition = $user_x->get();
  my $y_at_time_of_sub_definition = $original_y;
  $command_sub = sub {
    print_entries(
      $x_at_time_of_sub_definition,
      $y_at_time_of_sub_definition,
    );
  }
}
$mw->Button (
  -command => $command_sub,
);
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Instead of telling PerlTk to create the callback, create it yourself with an anonymous sub. This should work for you:

  -command => sub {
    print_entries(
      $user_x->get(),
      $user_y->get(),
      $original_x,
      $original_y,
    );
  },
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For reasons in the *real* application I need to create a call back to a real sub. Thank you, though for your insight on when variables are evaluated in brackets and sub calls.

Cheers!
--P



---

Don't worry about people stealing your ideas. If your ideas are any good, you'll have to ram them down people's throats.

-Howard Aiken