Leif K-Brooks wrote:
class CachingProperty(object):
def __init__(self, attr_name, calculate_function):
self._name = attr_name
self._calculate = calculate_function
def __get__(self, obj, type=None):
if obj is None:
return self
else:
value = self._calculate(obj)
setattr(obj, self._name, value)
return value
And example code:
>>> class Foo(object):
... def calculate_value(self):
... print 'Calculating...'
... return 42
... foo = CachingProperty('foo', calculate_value)
...
>>> bar = Foo()
>>> bar.__dict__
{}
>>> bar.foo
Calculating...
42
>>> bar.foo # Notice that the print statement doesn't run this time
42
>>> bar.__dict__
{'foo': 42}
To build on this for Python 2.4:
class Caches(object):
def __init__(self, calculate_function):
self._calculate = calculate_function
def __get__(self, obj, _=None):
if obj is None:
return self
value = self._calculate(obj)
setattr(obj, self._calculate.func_name, value)
return value
class Foo(object):
@Caches
def foo(self):
print 'Calculating...'
return 42
--Scott David Daniels
[EMAIL PROTECTED]
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