From: Robert Klemme <shortcutter@...>
Date: 2011-03-25T16:52:03+09:00
Subject: Re: shortcut for add unless nil ?

On Fri, Mar 25, 2011 at 7:02 AM, Iain Barnett <iainspeed@gmail.com> wrote:
>
> On 24 Mar 2011, at 18:53, Xavier Noria wrote:
>
>> You could do something like this (untested):
>>
>>    [a, b, c, d].compact.reduce(:+)
>>
>> though whether it is more clear is debatable. I think it reads fine if you're fluent.
>
> That works, thanks, though it starts to feel a bit messy if the array members aren't short vars and/or have square brackets too, as it gets pushed over several lines, and personally I dislike wrapping things with square brackets only to take them off just to use a fold. Whereas:
>
>    a +
>    [b,c,d] +
>    e +
>    f
>
> would read a lot better in that kind of situation. If it could be done :) The short vars in my example were due to typing laziness, I was thinking more for stuff like this:
>
>    HEADERS = ENV["BLAH_BLAH"] + ENV["BLAH_BLAH_BLAH_BLAH"]
>
> which begins to look unwieldy even with just two fairly long vars:
>
>    HEADERS = [ENV["BLAH_BLAH"] + ENV["BLAH_BLAH_BLAH"]].compact.reduce(:+)
>
> but
>
>    HEADERS = ENV["BLAH_BLAH"]           +
>              ENV["BLAH_BLAH_BLAH"]      +
>              ENV["BLAH_BLAH_BLAH_BLAH"]
>
> will remain clear even as the vars stack up.
>
> Much appreciated though.

What about

res = [a,b,c].inject([1]) {|r,x| x and r.concat(x) or r}

or

res = [a,b,c].inject([1]) {|r,x| x ? r.concat(x) : r}

or

res = [1]
[a,b,c].each {|x| x and res.concat x}

Kind regards

robert

-- 
remember.guy do |as, often| as.you_can - without end
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