cps::governor(3pm) [debian man page]

CPS::Governor(3pm)					User Contributed Perl Documentation					CPS::Governor(3pm)

NAME

       "CPS::Governor" - control the iteration of the "CPS" functions

DESCRIPTION

       Objects based on this abstract class are used by the "gk*" variants of the CPS functions, to control their behavior. These objects are
       expected to provide a method, "again", which the functions will use to re-invoke iterations of loops, and so on. By providing a different
       implementation of this method, governor objects can provide such behaviours as rate-limiting, asynchronisation or parallelism, and
       integration with event-based IO frameworks.

CONSTRUCTOR

   $gov = CPS::Governor->new
       Must be called on a subclass which implements the "again" method. Returns a new instance of a governor object in that class.

SUBCLASS METHODS

       Because this is an abstract class, instances of it can only be constructed on a subclass which implements the following methods:

   $gov->again( $code, @args )
       Execute the function given in the "CODE" reference $code, passing in the arguments @args. If this is going to be executed immediately, it
       should be invoked using a tail-call directly by the "again" method, so that the stack does not grow arbitrarily. This can be achieved by,
       for example:

	@_ = @args;
	goto &$code;

       Alternatively, the Sub::Call::Tail may be used to apply syntactic sugar, allowing you to write instead:

	use Sub::Call::Tail;
	...
	tail $code->( @args );

EXAMPLES

   A Governor With A Time Delay
       Consider the following subclass, which implements a "CPS::Governor" subclass that calls "sleep()" between every invocation.

	package Governor::Sleep

	use base qw( CPS::Governor );

	sub new
	{
	   my $class = shift;
	   my ( $delay ) = @_;

	   my $self = $class->SUPER::new;
	   $self->{delay} = $delay;

	   return $self;
	}

	sub again
	{
	   my $self = shift;
	   my $code = shift;

	   sleep $self->{delay};

	   # @args are still in @_
	   goto &$code;
	}

SEE ALSO

       o   Sub::Call::Tail - Tail calls for subroutines and methods

AUTHOR

       Paul Evans <leonerd@leonerd.org.uk>

perl v5.14.2							    2012-06-27							CPS::Governor(3pm)

Check Out this Related Man Page

IO::Async::Timer(3pm)					User Contributed Perl Documentation				     IO::Async::Timer(3pm)

NAME

       "IO::Async::Timer" - base class for Notifiers that use timed delays

DESCRIPTION

       This module provides a subclass of IO::Async::Notifier for implementing notifiers that use timed delays. For specific implementations, see
       one of the subclasses:

       o       IO::Async::Timer::Absolute - event callback at a fixed future time

       o       IO::Async::Timer::Countdown - event callback after a fixed delay

       o       IO::Async::Timer::Periodic - event callback at regular intervals

CONSTRUCTOR

   $timer = IO::Async::Timer->new( %args )
       Constructs a particular subclass of "IO::Async::Timer" object, and returns it. This constructor is provided for backward compatibility to
       older code which doesn't use the subclasses. New code should directly construct a subclass instead.

       mode => STRING
	       The type of timer to create. Currently the only allowed mode is "countdown" but more types may be added in the future.

       Once constructed, the "Timer" will need to be added to the "Loop" before it will work. It will also need to be started by the "start"
       method.

METHODS

   $running = $timer->is_running
       Returns true if the Timer has been started, and has not yet expired, or been stopped.

   $timer->start
       Starts the Timer. Throws an error if it was already running.

       If the Timer is not yet in a Loop, the actual start will be deferred until it is added. Once added, it will be running, and will expire at
       the given duration after the time it was added.

       As a convenience, $timer is returned. This may be useful for starting timers at construction time:

	$loop->add( IO::Async::Timer->new( ... )->start );

   $timer->stop
       Stops the Timer if it is running. If it has not yet been added to the "Loop" but there is a start pending, this will cancel it.

AUTHOR

       Paul Evans <leonerd@leonerd.org.uk>

perl v5.14.2							    2012-10-24						     IO::Async::Timer(3pm)

Linux and UNIX Man Pages

cps::governor(3pm) [debian man page]

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