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Subject: Re: lazy properties?
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From: "Stefan H. Holek" <stefan@epy.co.at>
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Date: Fri, 2 Nov 2012 09:36:11 +0100
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To: Andrea Crotti <andrea.crotti.0@gmail.com>
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On 01.11.2012, at 22:38, Andrea Crotti wrote:

> Seeing the wonderful "lazy val" in Scala I thought that I should try =
to get the following also in Python.
> The problem is that I often have this pattern in my code:
>=20
> class Sample:
>    def __init__(self):
>        self._var =3D None
>=20
>    @property
>    def var(self):
>        if self._var is None:
>            self._var =3D long_computation()
>        else:
>            return self._var
>=20
>=20
> which is quite useful when you have some expensive attribute to =
compute that is not going to change.
> I was trying to generalize it in a @lazy_property but my attempts so =
far failed, any help on how I could do that?

There is a ready made and well tested lazy decorator at =
http://pypi.python.org/pypi/lazy

Stefan

--=20
Stefan H. Holek
stefan@epy.co.at