@returnsnames('topicid', 'title', 'author')
def getmessage():
    return (3564395, 'Inline records', 'VladD2')

class A:
    def __init__(self):
        self.x = 0
        self.y = 'bla-bla-bla'

a = A()
a.x += a.y

class inlinerecord(tuple):

    def __new__(cls, dict):

        instance = super(inlinerecord, cls).__new__(cls, dict.values())

        instance.__dict__['names'] = tuple(dict.keys())

        for name, value in dict.iteritems(): instance.__dict__[name] = value

        return instance

    def __setattr__(self, *args):
        raise TypeError("can't modify immutable instance")

    __delattr__ = __setattr__

    def __eq__(self, other):
        return False if type(other) is not type(self) else self.names == other.names and super(inlinerecord, self).__eq__(other)

a = inlinerecord({'a': 0, 'b': 1})
b = inlinerecord({'a': 0, 'b': 1})
c = inlinerecord({'c': 0, 'b': 1})

print a.a, a.b
print b.a, b.b
print c.c, c.b

print a == b
print b == c
print a == c

0 1
0 1
0 1
True
False
False

KV>Да, конечно. Правда в процитированном тобой коде я дважды ошибся (один раз — фатально ), поэтому ниже — немного исправленный/дополненный вариант и целиком, ок?

class inlinerecord(tuple):
    def __new__(cls, dict):
        instance = super(inlinerecord, cls).__new__(cls, dict.values())
        instance.__dict__['names'] = tuple(dict.keys())
        for name, value in dict.iteritems(): instance.__dict__[name] = value
        return instance

    def __setattr__(self, *args):
        raise TypeError("can't modify immutable instance")
    __delattr__ = __setattr__

    def __eq__(self, other):
        return False if type(other) is not type(self) else self.names == other.names and super(inlinerecord, self).__eq__(other)

struct POINT3D {
  struct POINT plain;
  int z;
};

VD>(string ret1, int ret2) FuncName(string param1, int param2)
VD>

class TourKey
{
  public readonly string Name;
  public readonly DateTime BeginTime;
  public TourKey(string name, DateTime beginTime)
  {
    this.Name = name;
    this.BeginTime = beginTime;
  }
  public override bool Equals(object obj)
  {
    ...
  }
  public override int GetHashCode()
  {
    ...
  } 
}

TourKey GetTourKey(Tour tour)
{
  ...
}

class TourKey implement PairedKey<string, DateTime, First as Name, Second as BeginTime>;

TourKey GetTourKey(Tour tour)
{
  ...
}

class TourKey implement PairedKey<string, DateTime, First as Name, Second as BeginTime>;

class TourKey
{
  readonly PairedKey<string, DateTime> obj;

  public TourKey(string Name, DateTime BeginTime)
  {
    obj = new PairedKey<string, DateTime>(Name, BeginTime);
  }

  public string Name
  {
    get { return obj.First; }
  }

  public DateTime BeginTime
  {
    get { return obj.Second; }
  }

  public override int GetHashCode()
  {
    return obj.GetHashCode();
  }

  //Имплементация остальных методов PairedKey
}

struct POINT* p = (struct POINT*) p3d;
return p->getX(p);