jalanb3 wrote:
> Evening all,
>
> And thank you for your valuable reading skills.
>
> The following pattern turned up in coding tonight.
> It works, but I'm suspicious, it just seems too easy.
>
> So any comments or constructive criticisms welcome ?
>
> *** Start doctest format ***
>
> >>> class Cacher:
> ... def __init__(self):
> ... self.value_in_database = 0
> ...
> ... def very_slow_database_access(self):
> ... return self.value_in_database
> ...
> ... @property
> ... def show(self):
> ... result = self.very_slow_database_access()
> ... self.show = result
> ... return result
> ...
The above only works because properties don't work with classic class. If
you make Cacher a newstyle class (have it inherit from object) you'll get
an AttributeError. Therefore I think it would be cleaner to either
use __getattr__() or
change the Cacher to something like
class Cacher(object):
def __init__(self):
self._show = None
# ...
@property
def show(self):
result = self._show
if result is None:
result = self._show = self.very_slow_database_access()
return result
Peter
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