Tk "hello, world", part 2

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";
[download]

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.

Comment on Tk "hello, world", part 2 Download Code

Replies are listed 'Best First'.
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	[reply] [d/l] [select]
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]
Re: Re: Tk "hello, world", part 2 by RandomWalk (Beadle) on Jan 29, 2004 at 21:31 UTC
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]


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