From: Logan Capaldo <logancapaldo@...>
Date: 2007-07-10T09:51:40+09:00
Subject: Re: Syntax sugar: method[](...) => method(...)

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On 6/29/07, Erwin Abbott <erwin.abbott@gmail.com> wrote:
>
> Hi,
>
> The [] method is really handy when you have an object that should
> behave like a hash or array. One thing I find myself wishing I could
> also do is something like
>
> def logins[](date)
>   @events.select{|e| e.action == :login and e.date == date}
> end

class Module
  def bracket(name, &code)
    define_method("#{name}_bracketed", &code)
    m = instance_method("#{name}_bracketed")
    remove_method "#{name}_bracketed"

    define_method(name) do ||
       obj = Object.new
       m1 = m.bind(self)
       (class << obj; self; end).module_eval { define_method(:[]) { |x|
m1[x] } }
       obj
   end
  end
end


class Foo
   bracket :logins do |date|
     @data.select { |e| e.date == date }
  end
end

Who needs sugar?

(I so didn't test this at all)




There may be a better way to deal with this example, but this is just
> to demonstrate the circumstances where you don't have an array or hash
> called logins, but you'd like to be able to use that [] syntax. One
> way I though about doing it is
>
> def logins
>   EventList.new @events.select{|e| e.action == :login}
> end
>
> class EventList
>   def initialize data
>     @data = data
>   end
>   def [] date
>     @data.select{|e| e.date == date}
>   end
> end
>
> logins[Date.today] # => all logins today from @events
>
> I guess some people might prefer to write a method like
> get_logins(date), but I like this syntax.  It seems reasonable to also
> define []= in EventList to update the original @events. What I'd like
> to know is if there's another way to solve this problem, or if there
> are any simple optimizations (maybe only keep one instance of
> EventList and update its contents with each call to #events).
>
> Lastly, has there been any mention of allowing function names like so
> in ruby 1.9:
>   def logins[] date
>     # ...
>   end
>
> Thanks,
> - Erwin
>
>

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