From: Intransition <transfire@...>
Date: 2009-11-14T01:30:54+09:00
Subject: Re: Enumerable#find_yield, useful shortcut? better name?



On Nov 13, 9:12 am, Benoit Daloze <erego...@gmail.com> wrote:
> As Aaron,
> I prefer the simple built-in method, with what u want to do with the object
> after:
>
> obj1.foo? #=> false
> obj2.foo? #=> true
> obj2.foo  #=> "value"
>
> [obj1, obj2].find_yield { |obj| obj.foo if obj.foo? } #=> "value"
>
> [obj1, obj2].find { |obj| obj.foo? }.foo #=> "value"
>
> Even more concise ...
> The only problem I see is if we don't find, we'll call foo on nothing(nil).
>
> So to have the same behavior:
> x = [obj1, obj2].find(nil) { |obj| obj.foo? }
> x.foo unless foo.nil? #=> "value"
>
> And I think it's quite normal we have to manage with a structure(the if) how
> to manage when we didn't find.
>
> But I'm probably missing a special case. Could you give a example in
> situation, to see if it is easier to read or not?

I think you make a good point.  The difference lies in where you are
able to put the logic. Eg.

  x =  [obj1, obj2].find{ |obj| obj.foo? }
  y = x ? do_something_with(x.foo) : nil

vs.

  y =  [obj1, obj2].find_yield do |obj|
    do_something_with(obj.foo) if obj.foo?
  end

These are functionally equivalent, so really this is just a matter
constructional preference. If there were a way to make the former more
concise, then the case for the later would probably be moot, but I'm
not sure there is.