RandomWalk has asked for the wisdom of the Perl Monks concerning the following question:

Dear Monks,

I can run hello.pl as in Tk Tutorial but am having a little trouble with the next step. For instance, I would like to get input from an Entry widget instead of STDIN. I thought this should work but I'm not getting assigned as I expected: 

my $main = MainWindow->new();
$main->Label(-text=>"Company Name:")->pack();
my $entry = $main->Entry()->pack;
$entry->focus();
my $name = $entry->get();
$main->Button(-text=>"Continue", -command=> sub {$main->destroy})->pac
+k();
$main->Button(-text=>"Cancel", -command => sub {exit})->pack();
$main->bind('<Return>' => sub {$main->destroy});
MainLoop;
die "$name";

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Results only in

$ perl new_invoice.pl Died at new_invoice.pl line 38.

I guess when this works I'll try to make it more attractive with fonts and geometry management, and then maybe continue with the tutorial or "Mastering Perl/Tk".

I would appreciate any guidance. Thanks.

Replies are listed 'Best First'.
Re: Tk "hello, world", part 2
by arden (Curate) on Jan 29, 2004 at 20:51 UTC
    I prefer using -textvariable as Rhose++ pointed out, but if you really want to use ->get(), it needs to happen AFTER something is put into the Entry. Try this: 

    my $name;
my $main = MainWindow->new();
$main->Label(-text=>"Company Name:")->pack();
my $entry = $main->Entry()->pack;
$entry->focus();
$main->Button(-text=>"Continue", -command=> sub {$name = $entry->get()
+; $main->destroy();})->pack();
$main->Button(-text=>"Cancel", -command => sub {exit})->pack();
$main->bind('<Return>' => sub {$main->destroy});
MainLoop;
die "$name";

    [download]

    Also, next time, if you're going to include the error perl gave you, include all of the lines leading up to it. You can't have an error at line 38 of a 10 line script. . . :)

[reply]
[d/l]
      Thank you both.

      I guess I was using the get method as a way to see how MainLoop works. (Plus for a beginner there is comfort in having assignments isolated, explicit, and reference-free--but I'll just have to get used to the new syntax!)

      So it looks like I can't call the "get" method just once if I am to assign the entry text both upon button and return press. Right?

[reply]
Re: Tk "hello, world", part 2
by Rhose (Priest) on Jan 29, 2004 at 20:46 UTC
    You could also use -textvariable with your Entry widget. 
    #!/usr/bin/perl

use strict;
use warnings;

use Tk;

my $name;

my $main = MainWindow->new();
$main->Label(-text=>"Company Name:")->pack();
my $entry = $main->Entry(-textvariable => \$name)->pack;
$entry->focus();
$main->Button(-text=>"Continue", -command=> sub {$main->destroy;})->pa
+ck();
$main->Button(-text=>"Cancel", -command => sub {exit})->pack();
$main->bind('<Return>' => sub {$main->destroy});
MainLoop;
die "$name";

    [download]

    Update
    Oops... I forgot to put in the reason for the first code not working -- the problem is that the "$name = $entry->get();" line is being executed before there is a value in the Entry widget (You can't use the interface before the MainLoop;)

    Here is a "fix" for the first example:

    #!/usr/bin/perl

use strict;
use warnings;

use Tk;

my $name;

my $main = MainWindow->new();
$main->Label(-text=>"Company Name:")->pack();
my $entry = $main->Entry()->pack;
$entry->focus();
$main->Button(-text=>"Continue", -command=> sub {$name = $entry->get()
+;$main->destroy;})->pack();
$main->Button(-text=>"Cancel", -command => sub {exit})->pack();
$main->bind('<Return>' => sub {$main->destroy});
MainLoop;
die "$name";

    [download]

    Update 2
    Yeah, what arden said. *Smiles*

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