From: Tony Arcieri <tony.arcieri@...>
Date: 2010-10-12T11:59:27+09:00
Subject: Re: more idiomatic way to avoid errors when calling method on variable that may be nil?

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Haskell solves the "may be nil" problem with the Maybe monad (from Haskell).
There's many ways to implement something similar... such as implementing
Object#maybe whose method_missing (e.g. Maybe#method_missing) proxies to the
original object. NilClass can also implement #maybe, and always return nil.

On Mon, Oct 11, 2010 at 2:05 PM, Charles Calvert <cbciv@yahoo.com> wrote:

> I'm using Ruby 1.8.7 patchlevel 249
>
> Is there a more idiomatic way to do the following?
>
> var = hash[key].nil? ? nil : hash[key].downcase
>
> Note that if hash[key] is nil, I want nil assigned to var, so this
> won't work:
>
> var = hash[key].downcase unless hash[key].nil?
>
> Obviously I could do this, but I'm trying to keep it on one line:
>
> var = hash[key]
> var = var.downcase unless var.nil?
>
> --
> Charles Calvert
> Moderator - alt.computer.consultants.moderated
> Submission Address: accm@celticwolf.net
> Contact Address: accm_mod@celticwolf.net
>
>


-- 
Tony Arcieri
Medioh! A Kudelski Brand

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