# File lib/backports/1.8.7/array/product.rb, line 5 def product(*arg) # Implementation notes: We build a block that will generate all the combinations # by building it up successively using "inject" and starting with one # responsible to append the values. # result = [] arg.map!{|ary| Backports.coerce_to_ary(ary)} n = arg.inject(size) { |p, a| p * a.size } return [] if n == 0 raise RangeError, "too big a product" if n > 1<<31 arg.reverse! # to get the results in the same order as in MRI, vary the last argument first arg.push self outer_lambda = arg.inject(result.method(:push)) do |proc, values| lambda do |partial| values.each do |val| proc.call(partial.dup << val) end end end outer_lambda.call([]) result end