Using functions to populate Ruby hashes

Question

I get the following output from the code:

arr = [1,2,3]
gdu = {}
gdu = {
      "b" => 4,
      "c" => arr,
      "d" => arr.map {|x| x * gdu["b"].to_i },
      "e" => gdu["b"].to_i
}
gdu.default = "value does not exit in hash gdu"
gdu # => {"b"=>4, "c"=>[1, 2, 3], "d"=>[0, 0, 0], "e"=>0}

Why does the code here have this output?

Answer 1

You are setting the whole hash’s value at once, as one atomic operation. RHO uses the current version of gdu, which is an empty hash at the moment.

To achieve what you wanted, assign values step by step:

gdu = {}
gdu["b"] = 4
gdu["c"] = arr
gdu["d"] = arr.map { |x| x * gdu["b"] } # `to_i` is redundant
gdu["e"] => gdu["b"]