Given the following snippet of code below:

...
my $change_mode = \&change_mode;
...
#Case 1:  Callback routine called directly with anonymous reference
$main->Button(-text => 'To Lower Case',
              -command => sub { &change_mode(1) }
              )->pack;
...              
#Case 2:  Callback routine called with argument via named reference ve
+r. 1      
$main->Button(-text => 'To Upper Case',
              -command => &{$change_mode}(2)
              )->pack;
#Case 3:  Callback routine called with argument via named reference ve
+r. 2      
$main->Button(-text => 'To Mixed Case',
              -command => $change_mode->(3)
              )->pack;

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Why does case 1, which uses an anonymous reference to the subroutine, work, while case 2 and 3 fail? What is the proper syntax for passing arguments to a subroutine that has a named reference when using callbacks?

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In reply to Passing arguments to callback routines with named references by nysus

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