def _format_value(val, limit, level, len=len, repr=repr):
  """Format an arbitrary value as a compact string.

  This is a variant on Python's built-in repr() function, also
  borrowing some ideas from the repr.py standard library module, but
  tuned for speed even in extreme cases (like very large longs or very
  long strings) and safety (it never invokes user code).

  For structured data types like lists and objects it calls itself
  recursively; recursion is strictly limited by level.

  Python's basic types (numbers, strings, lists, tuples, dicts, bool,
  and None) are represented using their familiar Python notations.
  Objects are represented as ClassName<attr1=val1, attr2=val2, ...>.
  Portions omitted due to the various limits are represented using
  three dots ('...').

  Args:
    val: An arbitrary value.
    limit: Limit on the output length.
    level: Recursion level countdown.
    len, repr: Not arguments; for optimization.

  Returns:
    A str instance.
  """

  if level <= 0:
    return '...'

  typ = type(val)

  if typ in EASY_TYPES:
    if typ is float:
      rep = str(val)
    elif typ is long:
      if val >= 10L**99:
        return '...L'
      elif val <= -10L**98:
        return '-...L'
      else:
        rep = repr(val)
    else:
      rep = repr(val)
    if typ is long and len(rep) > limit:
      n1 = (limit - 3) // 2
      n2 = (limit - 3) - n1
      rep = rep[:n1] + '...' + rep[-n2:]
    return rep

  if typ in META_TYPES:
    return val.__name__

  if typ in STRING_TYPES:
    n1 = (limit - 3) // 2
    if n1 < 1:
      n1 = 1
    n2 = (limit - 3) - n1
    if n2 < 1:
      n2 = 1
    if len(val) > limit:
      rep = repr(val[:n1] + val[-n2:])
    else:
      rep = repr(val)
      if len(rep) <= limit:
        return rep
    return rep[:n1] + '...' + rep[-n2:]

  if typ is types.MethodType:
    if val.im_self is None:
      fmt = '<unbound method %s of %s>'
    else:
      fmt = '<method %s of %s<>>'
    if val.im_class is not None:
      return fmt % (val.__name__, val.im_class.__name__)
    else:
      return fmt % (val.__name__, '?')

  if typ is types.FunctionType:
    nam = val.__name__
    if nam == '<lambda>':
      return nam
    else:
      return '<function %s>' % val.__name__

  if typ is types.BuiltinFunctionType:
    if val.__self__ is not None:
      return '<built-in method %s of %s<>>' % (val.__name__,
                                               type(val.__self__).__name__)
    else:
      return '<built-in function %s>' % val.__name__

  if typ is types.ModuleType:
    if hasattr(val, '__file__'):
      return '<module %s>' % val.__name__
    else:
      return '<built-in module %s>' % val.__name__

  if typ is types.CodeType:
    return '<code object %s>' % val.co_name

  if isinstance(val, ProtocolBuffer.ProtocolMessage):
    buf = [val.__class__.__name__, '<']
    limit -= len(buf[0]) + 2
    append = buf.append
    first = True

    dct = getattr(val, '__dict__', None)
    if dct:
      for k, v in sorted(dct.items()):
        if k.startswith('has_') or not k.endswith('_'):
          continue
        name = k[:-1]

        has_method = getattr(val, 'has_' + name, None)
        if has_method is not None:



          if type(has_method) is not types.MethodType or not has_method():
            continue

        size_method = getattr(val, name + '_size', None)
        if size_method is not None:




          if type(size_method) is not types.MethodType or not size_method():
            continue



        if has_method is None and size_method is None:
          continue

        if first:
          first = False
        else:
          append(', ')
        limit -= len(name) + 2
        if limit <= 0:
          append('...')
          break
        append(name)
        append('=')
        rep = _format_value(v, limit, level-1)
        limit -= len(rep)
        append(rep)
    append('>')
    return ''.join(buf)

  dct = getattr(val, '__dict__', None)
  if type(dct) is dict:
    if typ is INSTANCE_TYPE:
      typ = val.__class__
    typnam = typ.__name__
    priv = '_' + typnam + '__'
    buffer = [typnam, '<']
    limit -= len(buffer[0]) + 2
    if len(dct) <= limit//4:
      names = sorted(dct)
    else:
      names = list(dct)
    append = buffer.append
    first = True

    if issubclass(typ, BUILTIN_TYPES):



      for builtin_typ in BUILTIN_TYPES:
        if issubclass(typ, builtin_typ):
          try:
            val = builtin_typ(val)
            assert type(val) is builtin_typ
          except Exception:
            break
          else:
            append(_format_value(val, limit, level-1))
            first = False
            break

    for nam in names:
      if not isinstance(nam, basestring):
        continue
      if first:
        first = False
      else:
        append(', ')
      pnam = nam
      if pnam.startswith(priv):
        pnam = pnam[len(priv)-2:]
      limit -= len(pnam) + 2
      if limit <= 0:
        append('...')
        break
      append(pnam)
      append('=')
      rep = _format_value(dct[nam], limit, level-1)
      limit -= len(rep)
      append(rep)
    append('>')
    return ''.join(buffer)

  how = CONTAINER_TYPES.get(typ)
  if how:
    head, tail = how
    buffer = [head]
    append = buffer.append
    limit -= 2
    series = val
    isdict = typ is dict
    if isdict and len(val) <= limit//4:
      series = sorted(val)
    try:
      for elem in series:
        if limit <= 0:
          append('...')
          break
        rep = _format_value(elem, limit, level-1)
        limit -= len(rep) + 2
        append(rep)
        if isdict:
          rep = _format_value(val[elem], limit, level-1)
          limit -= len(rep)
          append(':')
          append(rep)
        append(', ')
      if buffer[-1] == ', ':
        if tail == ')' and len(val) == 1:
          buffer[-1] = ',)'
        else:
          buffer[-1] = tail
      else:
        append(tail)
      return ''.join(buffer)
    except (RuntimeError, __HOLE__):


      return head + tail + ' (Container modified during iteration)'

  if issubclass(typ, BUILTIN_TYPES):



    for builtin_typ in BUILTIN_TYPES:
      if issubclass(typ, builtin_typ):
        try:
          val = builtin_typ(val)
          assert type(val) is builtin_typ
        except Exception:
          break
        else:
          typnam = typ.__name__
          limit -= len(typnam) + 2
          return '%s<%s>' % (typnam, _format_value(val, limit, level-1))

  if message is not None and isinstance(val, message.Message):
    buffer = [typ.__name__, '<']
    limit -= len(buffer[0]) + 2
    append = buffer.append
    first = True
    fields = val.ListFields()

    for f, v in fields:
      if first:
        first = False
      else:
        append(', ')
      name = f.name
      limit -= len(name) + 2
      if limit <= 0:
        append('...')
        break
      append(name)
      append('=')
      if f.label == f.LABEL_REPEATED:
        limit -= 2
        append('[')
        first_sub = True
        for item in v:
          if first_sub:
            first_sub = False
          else:
            limit -= 2
            append(', ')
          if limit <= 0:
            append('...')
            break
          rep = _format_value(item, limit, level-1)
          limit -= len(rep)
          append(rep)
        append(']')
      else:
        rep = _format_value(v, limit, level-1)
        limit -= len(rep)
        append(rep)
    append('>')
    return ''.join(buffer)

  return typ.__name__ + '<>'
dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/ext/appstats/formatting.py/_format_value