From: Brian Adkins <lojicdotcom@...>
Date: 2007-11-21T02:59:59+09:00
Subject: Re: Quick way to get attributes (without using collect)

On Nov 20, 12:12 pm, Farrel Lifson <farrel.lif...@gmail.com> wrote:
> On 20/11/2007, Max Williams <toastkid.willi...@gmail.com> wrote:
> > Say
> > i have an array of Employee objects, which have an attribute "name".  I
> > want to get all the names, as an array.
> > ...
> > What i want to do is something like this -
>
> >   employee_names = employees.names
>
> > But what i have to keep on doing is something like this -
>
> >   employee_names = employees.collect{ |emp| emp.name}
>
> You can use the Symbol#to_proc method
>
>  class Symbol
>     def to_proc
>       Proc.new {|e| e.send(self)}
>    end
>  end
>
> Which will let you right
>  employee_names = employees.collect(&:name)

map is shorter than collect. Also, adding optional args to to_proc
will make it more generally useful.

class Symbol
  def to_proc
    lambda {|obj, *args| obj.send(self, *args) }
  end
end

employee_names = employees.map(&:name)

I'd be wary of using method_missing for this.

Brian Adkins