From: Robert Klemme <shortcutter@...>
Date: 2009-05-05T00:03:44+09:00
Subject: Re: lazy lookup

2009/5/4 Thomas Hafner <thomas@faun.hafner.nl.eu.org>:
> Robert Klemme <shortcutter@googlemail.com> wrote/schrieb <763388F1amqkuU1@mid.individual.net>:
>
>> Sorry to sound discouraging but there is memoize already. The
>> difference is that not the whole Hash is filled but only the one
>> that you need for the argument list provided which seems potentially
>> more efficient.
>
> In my situation this ist not the case. The key value pairs can be
> retrieved by reading a file. It's better to open/read/close the file
> only once and retrieve all key value pairs at the same time. Of course
> the file should not be read at all, if never a value will be
> requested.
>
>> In case you want to fill the Hash completely you can just replace the
>> calculation code to assign multiple values.
>
> How does that look like? Somethink like that?:
>
>  Hash.new{ |h,k| h.replace(
>      COMPLETELY_CALCULATED_HASH
>    ); h[k] }

> (COMPLETELY_CALCULATED_HASH should be replaced by some code which
> calculates the hash completely)

I don't see the need for #replace. You can as well hand over h to the
routine that fetches the data.  But otherwise yes.  As a safety
measure you would probably also remember that you have loaded the Hash
in an instance variable of h.

Kind regards

robert


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