class MyClass(HasTraits):
….a = Float(1.234) #default value declared statically
.
.
class AnotherClass(HasTraits):
….a = Float()

….def _a_default(self): #dynamic init setup using naming convention
……..return 1.234

from enthought.traits.api import HasTraits, Float

class MyClass(HasTraits):
a = Float(1.234) #default value declared statically

class AnotherClass(HasTraits):
a = Float()

def _a_default(self): #dynamic init setup using naming convention
return 1.234

for the later, the 'a' attribute is calculated on demand.

Traits also does runtime type checking, notification, delegation and GUI-generation. There are also Property traits which are cacheable and handle depenencies. There are predefined traits for all the standard types and you can subclass your own.

The above just looks like a mess!

Another problem is you've defined only a read-only property: the decorator wraps the getter, but the property has no setter (or deleter or docstring).

>>> class C(object):
…
… @property
… def a(self):
… try:
… self._a
… except AttributeError:
… # Do possibly expensive stuff here
… self._a = <result of possibly expensive stuff>
… return self._a

I think this has better performance than using hasattr. Also, I wonder if having a @property and instance variable with the same name would cause problems somewhere; that's why I use `_a`.

Note: I didn't read other comments first. Sorry for any repetition.