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.\"
.IX Title "Eventloop 3pm"
.TH Eventloop 3pm 2024-03-07 "perl v5.38.2" "User Contributed Perl Documentation"
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.SH NAME
Tk::Event \- ToolKit for Events
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 1
\& use Tk::Event;
\&
\& Tk::Event\->fileevent(\e*FH, \*(Aqreadable\*(Aq => callback);
\&
\& Tk::Event\->lineavail(\e*FH, callback);
\&
\& use Tk::Event::Signal qw(INT);
\&
\& $SIG{\*(AqINT\*(Aq} = callback;
\&
\& use Tk::Event::process;
\&
\& Tk::Event\->proc($pid, callback);
\&
\& QueueEvent(callback [, position])
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
That is better than nothing but still hard to use. Most scripts want higher
level result (a line, a "block" of data etc.)
.PP
So it has occured to me that we could use new-ish TIEHANDLE thus:
.PP
.Vb 1
\& my $obj = tie SOMEHANDLE,Tk::Event::IO;
\& 
\& while (<SOMEHANDLE>)
\&  {
\&  }
.Ve
.PP
Then the READLINE routine registers a callback and looks something like:
.PP
.Vb 10
\& sub READLINE
\&  {
\&   my $obj = shift;
\&   Event\->io(*$obj,\*(Aqreadable\*(Aq,sub { sysread(*$obj,${*$obj},1,length(${*$obj}) });
\&   my $pos;
\&   while (($pos = index(${*$obj},$/) < 0)
\&    {
\&     DoOneEvent();
\&    }
\&   Event\->io(*$obj,\*(Aqreadable\*(Aq,\*(Aq\*(Aq); # unregister
\&   $pos += length($/);
\&   my $result = substr(${*$obj},0,$pos);
\&   substr(${*$obj},0,$pos) = \*(Aq\*(Aq;
\&   return $result;
\&  }
.Ve
.PP
This is using the scalar part of the glob representing the _inner_ IO
as a buffer in which to accumulate chars.