Tk::IO - high level interface to Tk's 'fileevent' mechanism

       Still not finished.  Idea is to use "exec" to emulate "system" in a non-blocking manner.

perl v5.40.1                                       2025-04-13                                            IO(3pm)

       Tk::IO is now layered on perl's IO::Handle class. Interfaces have changed, and are still evolving.

       In theory C methods which enable non-blocking IO as in earlier Tk-b* release(s) are still there. I have
       not changed them to use perl's additional Configure information, or tested them much.

       Assumption is that exec is used to fork a child process and a callback is called each time a complete
       line arrives up the implied pipe.

       "line" should probably be defined in terms of perl's input record separator but is not yet.

       The -childcommand callback is called when end-of-file occurs.

       $fh->wait can be used to wait for child process while processing other Tk events.

       $fh->kill can be used to send signal to child process.

       Tk::IO - high level interface to Tk's 'fileevent' mechanism

         my $fh = Tk::IO->new(-linecommand => callback, -childcommand => callback);
         $fh->exec("command")
         $fh->wait
         $fh->kill

       INTERFACES TO THIS MODULE MAY CHANGE AS PERL'S IO EVOLVES AND WITH PORT OF TK4.1