How do I change the data in a label in Perl Tk?

问题

I'm trying to create a program with Tk that will take the data from an entry, and, at the click of a button, create a label that has that data.

Below is the code I've been debugging. In the process of debugging, I have tried tb]geh following:

using references to $printItem
have the subroutine connected to -command go to a subroutine
combining the above in various ways

use Tk; use strict; use warnings;

$mw = MainWindow -> new;

my $printItem = $mw -> Entry(-width = 20); $printItem -> pack;

$mw -> Button(-text => "Write.", -command => sub{ $mw -> Label(-text => "$printItem") -> pack} -> pack;

MainLoop;

When I click the button, all that the label shows is Tk::Entry=HASH([seemingly random hexadecimal number here]). This is obviously not what I want, and I'd like to know how I can get the effect I desire.

回答1:

Tk::Entry=HASH(0xdeadbeef) is how Perl stringifies objects. And indeed, your $printItem variable stores an object of class Tk::Entry:

my $printItem = $mw -> Entry(-width = 20);

To get the string from a Tk::Entry widget, you can use its get method:

... -command => sub { $mw->Label(-text => $printItem->get)->pack } ...

Complete working example:

use strict;
use warnings;
use Tk;

my $mw = MainWindow->new;

my $printItem = $mw->Entry(-width => 20); $printItem->pack;

$mw->Button(-text => "Write.", -command => sub { $mw->Label(-text => $printItem->get)->pack })->pack;

MainLoop;

来源：https://stackoverflow.com/questions/56760432/how-do-i-change-the-data-in-a-label-in-perl-tk

标签

perl