From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2010-03-06T05:00:21+09:00
Subject: Re: Conditional keys in hash - out of the box?

On Fri, Mar 5, 2010 at 8:25 PM, Sven S. <svoop@delirium.ch> wrote:
> Hi
>
> Cumbersome title, here's what I'd like to do both elegantly and without
> monkey patching Hash:
>
> Say, I need to pass a hash to a method:
>
> mymethod :this => 'green'
>
> Now I'd like to include a second hash member only if a condition is met:
>
> mymethod :this => 'green, :that => ('blue' if condition)
>
> This of course leaves ":that => nil" in the hash if the condition is not
> met - which is no good, the key should just not be present at all. I
> could delete_if after that, but isn't there a more elegant way?

I'm not sure I understand. You want too add :that => 'blue' to the
hash only if condition?

h = {:this => 'green'}
h[:that] = 'blue' if condition
mymethod h

One liner:

mymethod(h = {:this => 'green'} && condition ? h.merge({:that => 'blue'}) : h)

A bit ugly, in my opinion. I like my first way better.

Jesus.