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Tk::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.