Tk won't output until finished

[packetstormer]

Sorry can't think of a better title!

I have the simple code below. When I pass a value to &check_card the $mw->label doesn't appear until the &check_in_SQLStore completes. This defeats the purpose!

I have even tried putting the label in it own function and calling that first (once card length >0) but it still waits for the next function to complete!

Autoflush to positive doesn't help and WaitBox seems a little ropy/difficult/OTT for what I need.

Could anyone suggest how I could make the "Please wait..." text appear while/before the check_in_SQLStore function executes?

#!/usr/bin/perl
use strict;
use warnings;
use Tk;
use DBI;

my $mw = MainWindow->new;
$mw->geometry("500x300+600+200");
my $text;

$mw->title("Account Details");

$mw->Label(
        -text => "Card Number:"
    )->pack(-side => 'top');

my $card =  $mw->Entry(-textvariable => '',
        -background => 'white', -width => 24)->pack(-side => 'top');



$mw->Button(
        -text => "Check Account",
        -command => \&check_card,
    )->pack(-side => 'top');

$mw->Button(
        -text => "Done",
        -command => sub {exit}
    )->pack(-side => 'top');



MainLoop;

sub check_card {
my $cardno = $card->get();
if(length $cardno =="0"){
    error_no_card();

}
elsif(length $cardno > "0") {
$mw->Label(-text => "\nChecking Account Details for '$cardno'.\n Pleas
+e Wait......\n",
         -width => 54)->pack();

}
             
if(length $cardno > "0"){
    my $exists = check_in_SQLStore($cardno);
if($exists =="0"){
    print "We got nothing\n";
}
}
    
}

sub error_no_card {
$mw->messageBox(-title => "Error!", -type=>'ok', -message => "Please e
+nter an Account Card number!",);
}

[Athanasius]

The following seems to work correctly:

sub check_card
{
    my $cardno = $card->get();

    if    (length $cardno == 0)
    {
        error_no_card();
    }
    elsif (length $cardno >  0)
    {
        $mw->Label
        (
            -text  => "\nChecking Account Details for '$cardno'.\n Ple
+ase Wait......\n",
            -width => 54,

        )->pack();

        $mw->update;

        my $exists = check_in_SQLStore($cardno);

        print "We got nothing\n" unless $exists;
    }
}

That is, call $mw->update; immediately after creating the label.

See, for example, the recent thread Perl/Tk window contents disappear when obscured then revealed.

Hope that helps,