Timers in Perl

Here’s the Perl translation of the Go code example for timers:

Our program demonstrates the use of timers in Perl. Timers allow us to execute code at some point in the future or repeatedly at some interval.

use strict;
use warnings;
use Time::HiRes qw(sleep);

# Timers represent a single event in the future. You
# tell the timer how long you want to wait, and it
# will execute a given code block after that time.
# This timer will wait 2 seconds.
my $timer1 = {
    seconds => 2,
    code => sub {
        print "Timer 1 fired\n";
    }
};

# We'll use sleep to simulate the timer firing
sleep($timer1->{seconds});
$timer1->{code}->();

# If you just wanted to wait, you could have used
# sleep directly. One reason a timer may be useful is
# that you can cancel the timer before it fires.
# Here's an example of that.
my $timer2 = {
    seconds => 1,
    code => sub {
        print "Timer 2 fired\n";
    }
};

my $timer2_thread = async {
    sleep($timer2->{seconds});
    $timer2->{code}->();
};

# Stop the timer
$timer2_thread->cancel();
print "Timer 2 stopped\n";

# Give the timer2 enough time to fire, if it ever
# was going to, to show it is in fact stopped.
sleep(2);

To run this program, save it as timers.pl and execute it with:

$ perl timers.pl
Timer 1 fired
Timer 2 stopped

The first timer will fire ~2s after we start the program, but the second should be stopped before it has a chance to fire.

Note that Perl doesn’t have built-in timer objects like Go does. Instead, we’ve simulated timers using hash references and the Time::HiRes module for high-resolution sleep. For the cancellable timer, we’ve used a simple threading model with the threads module. This is a basic approximation of Go’s timer functionality in Perl.

In a real-world scenario, you might want to use a more robust event loop or timer library, such as AnyEvent or POE, for more complex timer operations in Perl.

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