[Rails] Re: An idea for new syntactic sugar in Ruby

I also found this on stackoverflow:

http://stackoverflow.com/questions/3835170/ruby-assignment-and-comparison-in-one-line

On Feb 14, 5:18 pm, Kai Middleton <kai.middle...@gmail.com> wrote:
> I was looking at this bit of code within Rails:
>
> # File actionpack/lib/action_controller/metal/flash.rb, line 12
> def redirect_to(options = {}, response_status_and_flash = {}) #:doc:
>   if alert = response_status_and_flash.delete(:alert)
>     flash[:alert] = alert
>   end
>
>   if notice = response_status_and_flash.delete(:notice)
>     flash[:notice] = notice
>   end
>
>   if other_flashes = response_status_and_flash.delete(:flash)
>     flash.update(other_flashes)
>   end
>
>   super(options, response_status_and_flash)
> end
>
> And I thought: ouch, aren't those supposed to be double-equals?  Well,
> no, it's an assignment within an if statement.  It saves a line of
> code per usage, thus three lines of code in that method.
>
> But I thought: wow, that sure violates the principle of least
> surprise.  Perhaps it would be nice if there were a way to reference
> the most recent if-expression.  I recall how a lone underscore in irb
> will contain the value of whatever was last evaluated.  So perhaps
> something like this would be nice:
>
>   if response_status_and_flash.delete(:notice)
>     flash[:notice] = _
>   end
>
> instead of what we see above:
>
>   if notice = response_status_and_flash.delete(:notice)
>     flash[:notice] = notice
>   end

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