In the context of descriptors, the __set__ method is not called for
class attribute access. __set__ is only
called to set the attribute on an instance instance of the owner class
to a new value, value. WHY? Is there some other mechanism for
accomplishing this outcome. This subtle difference from __get__cost me
some time to track down. Might think about pointing that out the
documentation.
class RevealAccess(object):
"""A data descriptor that sets and returns values
normally and prints a message logging their access.
"""
def __init__(self, initval=None, name='var'):
self.val = initval
self.name = name
def __get__(self, obj, objtype):
print 'Retrieving', self.name
return self.val
def __set__(self, obj, val):
print 'Updating' , self.name
self.val = val
class MyClass(object):
x = RevealAccess(10, 'var "x"')
y = 5
print MyClass.x
MyClass.x = 20
print MyClass.x
MyClass.x = 30
print MyClass.x
Retrieving var "x"
10
20
30
I am at a lost on how to intercept class attribute sets. Can anyone
help :-/
Ryan
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