my $module = MyModule->new() ;
...
my $out = '' ;
{ local *STDOUT ;
   local *STDERR ;
   open (STDOUT,">>", \$out) ;
   open (STDERR,">>", \$out) ;
   $module->process() ;
}
....
##</code><code>##

use IPC::Open2 ;
....
sub process {
..
   my $pid = open2( *Reader, *Writer, "some_prog" );
   print Writer "$some_options" ;
   my @prog_out = <Reader> ;
   close Writer;
   close Reader;
   ..
  return @output ;
}
##</code><code>##

print STDOUT "....." ;

##</code><code>##

open OUT,">>", \$out ;
select OUT; $| = 1 ;