gistfile1.rb

def token(size=6)
  chars = ('0'..'9').to_a + ('a'..'z').to_a + ('A'..'Z').to_a
  chars.sample(size).inject("") { |result, char| result << char }
end

p token # => "aN7drK"
p token # => "tVO3HG"
p token(8) # => "UqeYGPL2"

=begin

If you look at the ASCII table, then you can see why I used 3 different ranges.
  
Array#sample grabs a random element from the array and when you give it an integer as an argument, then it will gram that many random elements.

Array#inject is the tricky part. It takes an object as an argument. It works just like Array#each, only it passes along your argument to the block and returns it. In the above example, I gave the inject block a new String instance and added each char to it. Since ruby returns the last thing evaluated in the method, then it will return the "injected" string.

=end