set_buffer_mode

Does anybody have a working example that actually uses the new
set_buffer_mode with in input buffer or an output buffer (and for
extra bonus points: and a read or a write callback)?

I tried to get it to work in a sample program, but I'm now wondering if
I misunderstood the way it's supposed to be used, or if the code is buggy
in the Stdio lib.

I'm currently using the test program below.  The read_cb doesn't seem
to be called ever, if I read from "in" instead of "i" then it actually
reads from the file, but the buffer is never used (neither is the read_cb).
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#!/usr/local/bin/pike

object in;
object out;
Stdio.Buffer i;
Stdio.Buffer o;

void tim()
{ werror("help\n");
  write("direct\n");
  werror("reading\n");
  string a = i->read(20);
  werror("got %O\ni:%O\n",a,(string)i);
  call_out(tim,2);
}

int read_cb(mixed id,Stdio.Buffer d)
{ werror("read_cb %O\n",(string)d);
  return 0;
}

int write_cb(mixed id,Stdio.Buffer d)
{ werror("write_cb %O\n",(string)d);
  return 0;
}

int main(int argc, array(string) argv)
{ i=Stdio.Buffer();
  o=Stdio.Buffer();
  in=Stdio.File();
  out=Stdio.File();
  //in->assign(Stdio.stdin);
  in=Stdio.File("/etc/group");
  out->assign(Stdio.stdout);

  in->set_buffer_mode(i);
  in->set_nonblocking(read_cb);
  out->set_buffer_mode(UNDEFINED,o);
  out->set_nonblocking(UNDEFINED,write_cb);
  
  call_out(tim,1);

  return -1;
}
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-- 
Stephen.