debian man page for tk::eventloop

Eventloop(3pm)						User Contributed Perl Documentation					    Eventloop(3pm)

NAME
       Tk::Event - ToolKit for Events

SYNOPSIS
	use Tk::Event;

	Tk::Event->fileevent(*FH, 'readable' => callback);

	Tk::Event->lineavail(*FH, callback);

	use Tk::Event::Signal qw(INT);

	$SIG{'INT'} = callback;

	use Tk::Event::process;

	Tk::Event->proc($pid, callback);

	QueueEvent(callback [, position])

DESCRIPTION
       That is better than nothing but still hard to use. Most scripts want higher level result (a line, a "block" of data etc.)

       So it has occured to me that we could use new-ish TIEHANDLE thus:

	my $obj = tie SOMEHANDLE,Tk::Event::IO;

	while (<SOMEHANDLE>)
	 {
	 }

       Then the READLINE routine registers a callback and looks something like:

	sub READLINE
	 {
	  my $obj = shift;
	  Event->io(*$obj,'readable',sub { sysread(*$obj,${*$obj},1,length(${*$obj}) });
	  my $pos;
	  while (($pos = index(${*$obj},$/) < 0)
	   {
	    DoOneEvent();
	   }
	  Event->io(*$obj,'readable',''); # unregister
	  $pos += length($/);
	  my $result = substr(${*$obj},0,$pos);
	  substr(${*$obj},0,$pos) = '';
	  return $result;
	 }

       This is using the scalar part of the glob representing the _inner_ IO as a buffer in which to accumulate chars.

perl v5.14.2							    2010-05-29							    Eventloop(3pm)