Mine

import structclass Struct(object):	__slots__ = ('__attrs__', '__baked__', '__defs__', '__endian__', '__next__', '__sizes__', '__values__')	int8 = ('b', 1)	uint8 = ('B', 1)		int16 = ('h', 2)	uint16 = ('H', 2)		int32 = ('l', 4)	uint32 = ('L', 4)		float = ('f', 4)		@classmethod	def string(cls, len):		return ('s', len)		LE = '<'	BE = '>'	__endian__ = '<'		def __init__(self):		self.__defs__ = []		self.__sizes__ = []		self.__attrs__ = []		self.__values__ = {}		self.__next__ = True		self.__baked__ = False				self.__format__()				self.__baked__ = True		def __setattr__(self, name, value):		if name in self.__slots__:			return object.__setattr__(self, name, value)				if self.__baked__ == False:			type, size = value						if type == 's':				self.__defs__.append(Struct.string)				self.__sizes__.append(size)				self.__attrs__.append(name)				self.__values__[name] = ''				self.__next__ = True			else:				if self.__next__:					self.__defs__.append('')					self.__sizes__.append(0)					self.__attrs__.append([])					self.__next__ = False								self.__defs__[-1] += type				self.__sizes__[-1] += size				self.__attrs__[-1].append(name)				self.__values__[name] = 0		else:			self.__values__[name] = value		def __getattr__(self, name):		if self.__baked__ == False:			return name		else:			try:				return self.__values__[name]			except KeyError:				raise AttributeError(name)		def unpack(self, data):		pos = 0		for i in range(len(self.__defs__)):			sdef, size, attrs = self.__defs__[i], self.__sizes__[i], self.__attrs__[i]						if sdef == Struct.string:				if isinstance(size, str):					size = self.__values__[size]				self.__values__[attrs] = data[pos:pos+size]				pos += size			else:				values = struct.unpack(self.__endian__+sdef, data[pos:pos+size])				pos += size				j = 0				for name in attrs:					self.__values__[name] = values[j]					j += 1				return self		def pack(self):		ret = ''		for i in range(len(self.__defs__)):			sdef, size, attrs = self.__defs__[i], self.__sizes__[i], self.__attrs__[i]						if sdef == Struct.string:				if isinstance(size, str):					size = self.__values__[size]				temp = self.__values__[attrs][:size]				ret += temp + ('\0' * (size - len(temp)))			else:				values = [self.__values__[name] for name in attrs]				ret += struct.pack(self.__endian__+sdef, *values)		return retif __name__=='__main__':	class TestStruct(Struct):		__endian__ = Struct.LE		def __format__(self):			self.foo, self.bar = Struct.uint32, Struct.float			self.baz = Struct.string(8)						self.omg = Struct.uint32			self.wtf = Struct.string(self.omg)		test = TestStruct()	test.unpack('\xEF\xBE\xAD\xDE\x00\x00\x80\x3Fdeadbeef\x04\x00\x00\x00test')	print test.bar	assert test.foo == 0xDEADBEEF	assert test.bar == 1.0	assert test.baz == 'deadbeef'	assert test.omg == 4	assert test.wtf == 'test'		test.foo = 0xCAFEBABE	test.bar = 0.0	assert test.pack() == '\xBE\xBA\xFE\xCA\0\0\0\0deadbeef\x04\x00\x00\x00test'