cached_property decorator

cached_property.py

from functools import wraps

def cached_property(fn):
    @wraps(fn)
    def wrapper(self):
        cache_var = '_%s' % fn.__name__
        if not hasattr(self, cache_var):
            setattr(self, cache_var, fn(self))
        return getattr(self, cache_var)
    return property(wrapper)

usage.py

from cached_property import cached_property

class UsageExample(object):

    @cached_property
    def slow_property(self):
        # access_database()

o = UsageExample()
o.slow_property # hits database
o.slow_property # uses data cached in memory