class Immutable(object):
"""An immutable class.
"""
_mutable = False
def __setattr__(self, name,value):
if self._mutable or name == '_mutable':
super(Immutable,self).__setattr__(name,value)
else:
raise TypeError("Can't modify immutable instance")
def __delattr__(self,name):
if self._mutable:
super(Immutable,self).__delattr__(name)
else:
raise TypeError("Can't modify immutable instance")
def mutablemethod(f):
def func(self,*args, **kwargs):
if isinstance(self,Immutable):
old_mutable = self._mutable
self._mutable = True
res = f(self,*args, **kwargs)
self._mutable = old_mutable
else:
res = f(self,*args, **kwargs)
return res
return func
if __name__ == '__main__':
class A(Immutable):
'''
Define __init__ can set attributes for instance
'''
@mutablemethod
def __init__(self,value):
super(A,self).__init__(self)
self.value = value
def try_change(self,value):
self.value = value
a = A("test")
a.try_change("TEST")
a.value = "TEST"
Diff to Previous Revision
--- revision 1 2010-04-22 19:39:32
+++ revision 2 2010-04-23 08:30:50
@@ -43,6 +43,6 @@
def try_change(self,value):
self.value = value
-a = A("test")
-a.try_change("TEST")
-a.value = "TEST"
+ a = A("test")
+ a.try_change("TEST")
+ a.value = "TEST"
