From: "nikolai.weibull@..." <nikolai.weibull@...>
Date: 2007-08-14T20:59:58+09:00
Subject: Re: Does an Array#apply make any sense at all?

On Aug 14, 1:51 pm, "Robert Klemme" <shortcut...@googlemail.com>
wrote:
> 2007/8/14, nikolai.weib...@gmail.com <nikolai.weib...@gmail.com>:
>
>
>
> > Hi!
>
> > I wanted to write a simple method for comparing two paths on a Windows
> > system.  My initial algorithm felt very contrived:
>
> > def same_path?(a, b)
> >   a, b = [a, b].map{ |p| File.expand_path(p).downcase }
> >   a == b
> > end
>
> > It felt like saving the result from #map and then doing the comparison
> > shouldn't be necessary.  So I came up with the following solution:
>
> > class Array
> >   def apply(method)
> >     shift.send(method, *self)
> >   end
> > end
>
> > This allowed me to define #same_path? thusly:
>
> > def same_path?(a, b)
> >   [a, b].map{ |p| File.expand_path(p).downcase }.apply(:==)
> > end
>
> > which, to me, looks a lot nicer.  Array#apply takes a method (in a
> > symbolic manner) and applies it to its first element, passing the rest
> > of the elements as arguments to the given method.
>
> > Any thoughts?  Is Array#apply a method that could potentially have
> > other uses than my specific example above?
>
> Your method should be called "apply!" because it's destructive.  I'd
> rather not do it that way, i.e. without changing the array at hand.You
> can use inject for that.
>
> I'd use #inject for your problem:
>
> match = [a,b].map {|x| File.expand_path(x).downcase}.inject {|x,y| x==y}

Ah, I had no idea inject would take the first item of an array if not
given an argument; thanks!  That solves my problem.

  nikolai