RCR 62: Kernel::rand to accept Range

Range#rand and Array#rand would also be useful:

  (45..96).rand<br>

  [23, 67, 34, 68].rand<br>

Any thoughts on randomly removing an element from an array vs randomly selecting?

class Array

  def rand() at super(size)<br>
  end<br>

end

then to put a random item from a range:

(0..10).to_a.rand

to get a random line from a file:

File.new("foo.txt", "r").read.split.rand

One danger of this is that Range.to_a might return a ridiculous number of elements.

I'm not convinced that it makes sense to make this an instance method. Here's an implentation that overrides rand() to work on any container that has size() and each() defined:

module Kernel

  orig_rand = method(:rand)
  define_method(:rand) do |x|
    if x.respond_to?(:each) and x.respond_to?(:size) then
      raise ArgumentError, "Invalid container size" if x.size == 0
      n = rand(x.size); j = 0
      for y in x do
        break if j == n
        j += 1
      end
      y # return
    else
      orig_rand.call(x) # return
    end
  end

end
p rand(10)
p rand(2..20)
p rand([100, 200, 300, 400])
p rand({1=>2, 2=>3, 3=>4, 4=>5})

Kernel#rand(min = 0, max = 1, int = false)

Seems excessive to need a range object to specify a lower and upper bound. It'd be nice to specify whether or not it should be an int too. ;~) More sugar. :~)

I really like that. You could also optimize it so that if an object responds to at, (Array or String), it wouldn't iterate through them all.