Is There Any Way To Create A Class Property In Python?

The following doesn't work for some reason: >>> class foo(object): ... @property ... @classmethod ... def bar(cls): ... return 'asdf' ... >>

Solution 1:

If you want the descriptor property to trigger when you get an attribute from object X, then you must put the descriptor in type(X). So if X is a class, the descriptor must go in the class's type, also known as the class's metaclass -- no "trickery" involved, it's just a matter of completely general rules.

Alternatively, you might write your own special-purpose descriptor. See here for an excellent "how-to" treaty on descriptors. Edit for example:

classclassprop(object):
  def__init__(self, f):
    self.f = classmethod(f)
  def__get__(self, *a):
    return self.f.__get__(*a)()

classbuh(object):
  @classpropdefbah(cls): return23print buh.bah

emits 23, as desired.