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Re: lazy properties?

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  Re: lazy properties? "Stefan H. Holek" <stefan@epy.co.at> - 2012-11-02 09:36 +0100

#32601 — Re: lazy properties?

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:
> 
> class Sample:
>    def __init__(self):
>        self._var = None
> 
>    @property
>    def var(self):
>        if self._var is None:
>            self._var = long_computation()
>        else:
>            return self._var
> 
> 
> 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

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

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