From: twifkak@...
Date: 2005-07-20T05:36:46+09:00
Subject: Re: Regarding rand

> Thanks guys,
> 
> Daniel, I started out with something similar to that, although yours
> is alot better, but then thought it would be nice to have something
> like random 'a'..'z' aswell or even random Thing.new(1)..Thing.new(6)
> . Which i'll probably not need anyway so i'll 'borrow' yours if I may.
Ha! I had to ri Range to actually find out how it supported Ranging Things. Now I know. That's neat.

> Devin, thanks, 1) will do!, i'm going to go and have a look at the
> pickaxe to see why.
Yes, singleton methods are the elixir of life.

> 2) I was vaguely aware that creating the arrays
> could be a bad idea for big ranges but couldn't work out how to get
> the nth member of a range except by doing something like
> 
> value = range.first
> for  1..n
>   value = value.succ
> end
Yeah, that's probably right. I imagine Range#each looks like this
class Range
 def each
  value = self.first
  loop do
   yield value
   break if value == self.last
   value = value.succ
  end
 end
end

> which seemed a bit nasty or by getting the entries which seemed quite
> nice in light of the chapter I read about duck typing
Yeah, I guess don't bother changing it until you need to get a random thing from a very large Range, in which case, you might want to provide further optimizations for things like Integer. You can still have fun with duck typing my way, though!

class Range
 def rand
  if self.first.respond_to? :rand_to
   self.first.rand_to(self.last)
  else
   # normal implementation goes here
  end
 end
end
class Array
 def rand
  # normal implementation goes here
 end
end
class Integer
 def rand_to(last)
  self + rand(last - self)
 end
end
...
foo.rand #where foo is whatever

> Ben (Ruby Newbie)
Oh, but the good kind. The kind that's not afraid to dive deep into the language features. (Honestly, I fall under RubyNuby compared to most of the people on this list. I'm just vocal for the time being.)

Devin