#!/python22/bin/python
import types

class Var(object):
	DEFAULT_VALUE = None
	BASETYPE = str
	
	def __init__(self, value=None, *variables):
		#	create all private variables
		self._value = self.DEFAULT_VALUE
		self.variables = variables
		self._change_callbacks = []

		#	init variables
		self.value = value
		
	def _call_change_callbacks(self, old, new):
		for callback in self._change_callbacks:
			callback(self, old, new)
			
	def bind(self, callback):
		self._change_callbacks.append(callback)
			
	def unbind(self, callback, secure=False):
		try:
			self._change_callbacks.remove(callback)
			return True
		except ValueError:
			if secure:
				return False
			else:
				raise
			
	def __add__(self, other): return self.value + other
	def __sub__(self, other): return self.value - other
	def __mul__(self, other): return self.value * other
	def __div__(self, other): return self.value / other
	def __mod__(self, other): return self.value % other
	def __radd__(self, other): return other + self.value
	def __rsub__(self, other): return other - self.value
	def __rmul__(self, other): return other * self.value
	def __rdiv__(self, other): return other /self.value
	def __rmod__(self, other): return other % self.value

	def _set(self, value):
		_old = self._value
		self._value = value
		self._call_change_callbacks(_old, value)
		
	def _get(self):
	    if self.variables:
	        return self._value % self.variables
	    else:
	        return self._value

	def _del(self):
		self._value = self.DEFAULT_VALUE
		
	def __repr__(self):
		return "<object of %s>  value=%s" % (
			repr(self.__class__)[1:-1], 
			repr(self._value)
		)
	
	def __call__(self, *arg):
		if arg:
			self.value = arg[0]
		else:
			return self.value
		
	def __str__(self):
	    if self.variables:
	        return str(self._value) % self.variables
	    else:
	        return str(self._value)

	def __int__(self):
	    return int(self._value)

	def __float__(self):
	    return float(self._value)

	def __bool__(self):
	    return self.__nonzero__()

	def __nonzero__(self):
	    if self._value:
	        return True
	    else:
	        return False

	value = property(_get, _set, _del)
	
class StringVar(Var):
	DEFAULT_VALUE = ""
	BASETYPE = str
	
	def __init__(self, value=None, *variables):
		Var.__init__(self, value or self.DEFAULT_VALUE, *variables)
			
	def _set(self, value):
		if isinstance(value, (str, unicode, self.__class__)):
			Var._set(self, value)
		else:
			raise TypeError, \
				"Type must be string, unicode or StringVar, found %s instead." % str(type(value))
			return
			
	value = property(Var._get, _set, Var._del)
	

class IntVar(Var):
	DEFAULT_VALUE = 0
	BASETYPE = int
	
	def __init__(self, value=None):
		Var.__init__(self, value or self.DEFAULT_VALUE)
		
	def _set(self, value):
		if isinstance(value, (int, long, self.__class__)):
			Var._set(self, value)
		else:
			raise TypeError, \
				"Type must be int, long or IntVar, found %s instead." % str(type(value))
				
	value = property(Var._get, _set, Var._del)
	

class FloatVar(Var):	
	DEFAULT_VALUE = 0.0
	BASETYPE = float
	
	def __init__(self, value=None):
		Var.__init__(self, value or self.DEFAULT_VALUE)
		
	def _set(self, value):
		if isinstance(value, (float, self.__class__)):
			self._value = value
		elif isinstance(value, (int, long)):
			self._value = float(value)
		else:
			raise TypeError, \
				"Type must be float, int or long, found %s instead." % str(type(value))
				
	value = property(Var._get, _set, Var._del)

class BoolVar(Var):
    DEFAULT_VALUE = False
    BASETYPE = bool
    
    def __init__(self, value=None):
        Var.__init__(self, value or self.DEFAULT_VALUE)
        
    def _set(self, value):
        self._value = bool(value)
        
    value = property(Var._get, _set, Var._del)

def out(var, old, new):
	print "Wert von", var.__class__, "aenderte sich von", old, "zu", new