sS limitedStruct(int limit, O o) {
  var baos = new ByteArrayOutputStream();
  var out = new LimitedOutputStream(baos, limit);
  var writer = printWriter(out);
  
  embedded void failMe() {
    fail("Struct exceeds limit of " + n2(limit) + " bytes: " + shorten(fromUtf8(baos.toByteArray()), limit));
  }
  
  try {
    structureToPrintWriter(o, writer);
  } catch e {
    writer.close();
    failMe();
  }
  writer.close();
  S struct = fromUtf8(baos.toByteArray());
  if (l(struct) > limit)
    failMe();
  ret struct;
}