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# NAME

Async::Event::Interval - Scheduled and one-off asynchronous events

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# SYNOPSIS

A simple event that updates JSON data from a website using a shared scalar
variable, while allowing the main application to continue running in the
foreground. Multiple events can be simultaneously used if desired.

See ["EXAMPLES"](#examples) for other various functionality of this module.

    use warnings;
    use strict;

    use Async::Event::Interval;

    my $event = Async::Event::Interval->new(2, \&callback);

    my $json = $event->shared_scalar;

    $event->start;

    while (1) {
        print "$$json\n";

        #... do other things

        $event->restart if $event->error;
    }

    sub callback {
        $$json = ...; # Fetch JSON from website
    }

# DESCRIPTION

Very basic implementation of asynchronous events triggered by a timed interval.
If a time of zero is specified, we'll run the event only once.

# METHODS - EVENT OPERATION

## new($delay, $callback, @params)

Returns a new `Async::Event::Interval` object. Does not create the event. Use
`start` for that.

Parameters:

    $delay

Mandatory: The interval on which to trigger your event callback, in seconds.
Represent partial seconds as a floating point number. If zero is specified,
we'll simply run the event once and stop.

    $callback

Mandatory: A reference to a subroutine that will be called every time the
interval expires.

    @params

Optional, List: A list of parameters to pass to the callback. Note that these
are not shared parameters and are a copy only, so changes to them in the main
code will not be seen in the event, and vice-versa. See ["shared\_scalar"](#shared_scalar) if
you'd like to use variables that can be shared between the main application and
the events.

## start

Starts the event timer. Each time the interval is reached, the event callback
is executed.

## stop

Stops the event from being executed.

## restart

Alias for `start()`. Re-starts a `stop()`ped event.

## status

Returns the event's process ID (true) if it is running, `0` (false) if it
isn't.

## waiting

Returns true if the event is dormant and is ready for a `start()` or
`restart()` command. Returns false if the event is already running.

## error

Returns true if an event crashed unexpectedly in the background, and is ready
for a `start()` or `restart()` command. Returns false if the event is not in
an error state.

## interval($seconds)