From: Robert Dober <robert.dober@...>
Date: 2009-08-14T00:40:01+09:00
Subject: Re: Simple If

On Thu, Aug 13, 2009 at 5:00 PM, Robert
Klemme<shortcutter@googlemail.com> wrote:
> 2009/8/13 Robert Dober <robert.dober@gmail.com>:
>> On Thu, Aug 13, 2009 at 10:18 AM, Anthony Eden<anthonyeden@gmail.com> wrote:
>>> On Wed, Aug 12, 2009 at 10:14 PM, Pete Moran<pete@zoborg.com> wrote:
>>>> UPDATE:
>>>>
>>>> This works
>>>>
>>>>    if params[:country][:id]
>>>>      id = params[:country][:id]
>>>>    else
>>>>      id = params[:id]
>>>>    end
>>>>
>>>> But is there a oneliner equivalent?
>>>
>>> id = params[:country][:id] || params[:id]
>> maybe safer but still not safe
>>
>> id = params[:country] && params[:country][:id] || params[:id]
>
> I'd go for
>
> id = (params[:country] || params)[:id]
that is nicely refactored
>
> But, this does not seem to be what OP needs.  The Perl code was
>
> my $id = (exists $hash->{id}) ? $hash->{id} : $_;
>
> For me that translates to something like this:
>
> def any_method(some_id_argument)
>  id = @hash[:id] || some_id_argument
not really, rather
   id = @hash.fetch( :id, some_id_argument)
or the fancier
   id = @hash.fetch( :id ){ some_id_argument }

just for completeness ;) of the API. (This is interesting for some use
cases as e.g. throwing an exception in the block, thus

begin
  @hash.fetch( :id )
rescue KeyNotFoundIBelieve
   raise OMGWhatDidYouDo
end

becomes

@hash.fetch( :id ){ raise OMGWhatDidYouDo, "<b>AGAIN</b>" } ;)

HTH
Robert
>  ...
> end
>
> Kind regards
>
> robert
>
> --
> remember.guy do |as, often| as.you_can - without end
> http://blog.rubybestpractices.com/
>
>



-- 
module Kernel
  alias_method :λ, :lambda
end