From: Joel VanderWerf <vjoel@...>
Date: 2009-02-13T07:42:05+09:00
Subject: Re: Better way to do this?

Pito Salas wrote:
> Hi,
> 
> I seem to be repeating myself in the following little bit:
> 
> if (!@options[:namespace].nil?)
>     namespace_options = @options[:namespace]
>     root.add_namespace(namespace_options[:namespace],
> namespace_options[:value])
> end
> 
> Can someone show me a way to not repeat options[:namespace] ?
> 
> Simpler example of the exact same:
> 
> if (!hash[:value].nil?)
>     h = hash[:value]
>     puts h[:left], h[:right]
> end

hash = {
   :value => {:left => 1, :right => 2}
}

# original:
if (!hash[:value].nil?)
     h = hash[:value]
     puts h[:left], h[:right]
end

# looking up :value only once
h = hash[:value]
if h ## assuming you don't use false as a value in the hash
   puts h[:left], h[:right]
end

# living a little dangerously (assignment in conditional):
if (h = hash[:value])
   puts h[:left], h[:right]
end

# more compactly, if you care:
h = hash[:value] and puts h[:left], h[:right]

# the last one depends on 'and' having low precedence (unlike &&)

-- 
       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407