Refactoring random number generation

Question

As I'm learning Ruby I wrote this little program to generate a "nice" number randomly (like 4747, 6969, etc.). As I'm currently breaking the "do not repeat yourself" rule, how would you refactor the following?

def nice_numbers
    a = rand(9)
    b = rand(9)
    c = rand(9)
    d = rand(9)
    while a != c || b != d
        a = rand(9)
        b = rand(9)
        c = rand(9)
        d = rand(9)
    end
    nice = [a,b,c,d].join
end

puts nice_numbers

Answer 1

The code:

def nice_numbers
  ([rand(9),rand(9)]*2).join
end

generates the same output as your function. It is also faster, as it does not test then regenerate anything.

If you want to DRY this up for rand(9):

def nice_numbers
  (Array.new(2) {rand(9)} * 2).join
end

Ruby language features used in this last example:

• Array constructor takes a size param and a block to fill the Array

• Multiplying an array by an integer repeats the array