in reply to Understanding callbacks

Have a look at Tk::UserGuide for examples of how a gui uses callbacks.

The first example is this :-

    #!/usr/bin/perl -w  
        use Tk;
        use strict;

        my $mw = MainWindow->new;
        $mw->Label(-text => 'Hello, world!')->pack;
        $mw->Button(
            -text    => 'Quit',
            -command => sub { exit },
        )->pack;
        MainLoop;

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The program sets up the gui then calls MainLoop and never returns, only when the user clicks on the button will the callback -command get called.

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Re^2: Understanding callbacks
by stevieb (Canon) on Jun 14, 2015 at 20:46 UTC

    I very much appreciate everyone's feedback in this thread, but I'm replying here as this post (after reading through the docs of Tk) showed me that I wasn't really trying to understand callbacks, but as a few stated, Event Driven Programming.

    I just didn't correlate the two so deeply, but now I fully understand the purpose of a callback in non-event driven apps (grep was a *great* example for me to grasp).

    Although I don't have any need to do GUI programming, I am going to play around with it for a while so I can grasp this event-driven thing, as I want to fully understand how it works so perhaps one day I can incorporate some of their benefits into apps I do write on a daily basis.

    Again, thanks to all the Monks who replied with such in-depth and thought-out posts to help me understand not just about callbacks, but programming at another level.

    Thanks and regards,

    -stevieb

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