Active object: Difference between revisions

=={{header|Perl 6}}==

{{works with|Rakudo|2018.12}}

There is some jitter in the timer, but it is typically accurate to within a few thousandths of a second.

<lang perl6>class Integrator {

has $.f is rw = sub ($t) { 0 };

has $.now is rw;

has $.value is rw = 0;

has $.integrator is rw;

method init() {

self.value = &(self.f)(0);

self.integrator = Thread.new(

:code({

loop {

my $t1 = now;

self.value += (&(self.f)(self.now) + &(self.f)($t1)) * ($t1 - self.now) / 2;

self.now = $t1;

sleep .001;

}

}),

:app_lifetime(True)

).run

}

method Input (&f-of-t) {

self.init;

self.f = &f-of-t;

self.now = now;

}

method Output { self.value }

}

my $a = Integrator.new;

$a.Input( sub ($t) {sin(pi * $t) } );

say "Initial value: ", $a.Output;

sleep 2;

say "After 2 seconds: ", $a.Output;

$a.Input( sub ($t) { 0 } );

sleep .5;

say "f(0): ", $a.Output;</lang>

{{out|Typical output}}

<pre>Initial value: 0

After 2 seconds: -0.0005555887464620366

f(0): 0</pre>