How to memoize/cache property access?

[thebjorn]

On Dec 20, 5:43 pm, Michele Simionato <michele.simion... at gmail.com>
wrote:
> On Dec 20, 5:02 pm, thebjorn <BjornSteinarFjeldPetter... at gmail.com>
> wrote:
>
> > I seem to be writing the following boilerplate/pattern quite
> > frequently to avoid hitting the database until absolutely necessary ...
>
> I use the following module:
[...]

I love it!  much better name too ;-)

I changed your testcase to include a second cached property (the
naming is in honor of my late professor in Optimization of Functional
Languages class: "...any implementation that calls bomb_moscow is per
definition wrong, even if the program produces the correct result..."
-- it was a while ago ;-)

if __name__ == '__main__': # a simple test
    import itertools
    counter = itertools.count()
    class Test(object):
        @cached
        def foo(self):
            return counter.next()

        @cached
        def bomb_moscow(self):
            print 'fire missiles'
            return counter.next()

        reset = cached.reset

it didn't start WWIII, but I had to protect attribute deletion to get
it to run:

        def fdel(s):
            if private in s.__dict__:
                del s.__dict__[private]

I'm a bit ambivalent about the reset functionality. While it's a
wonderful demonstration of a staticmethod, the very few times I've
felt the need to "freshen-up" the object, I've always felt it was best
to create it again from scratch. Do you have many uses of it in your
code?

-- bjorn