Gives an example of the use case of to struct and benchmarks against OpenStruct.

to_struct_example.rb

require "json"
require 'benchmark'
require 'bigdecimal/math'

class Hash
  def to_struct
    Struct.new(*(k = self.keys)).new(*self.values_at(*k))
  end
end

# You have a hash that you have built in your app
sample_hash = {
  foo_key: "foo_val",
  bar_key: "bar_val",
  baz_key: "baz_val",
}

# Then you have JSON coming from some external api
json_response = "{\"qux_key\":\"qux_val\",\"quux_key\":\"quux_val\",\"corge_key\":\"corge_val\"}"
hash_with_unknown_keys = JSON.parse(json_response)

# Merge these two together
sample_hash.merge!(hash_with_unknown_keys)

iterations = 100_000

Benchmark.bm do |bm|
  bm.report "#to_struct" do
    iterations.times do
      # Would be super nice if I could convert this to a struct with a method
      # Somehow a bit faster than the explicit example below and much faster than open struct
      sample_struct = sample_hash.to_struct
      sample_struct.foo_key
    end
  end

  bm.report "Struct" do
    iterations.times do
      sample_struct = Struct.new(:foo_key, :bar_key, :baz_key, :quux_key, :quux_key, :corge_key)
        .new("foo_val", "bar_val", "baz_val", "qux_val", "quux_val", "corge_val")
      sample_struct.foo_key
    end
  end

  bm.report "OpenStruct" do
    iterations.times do
      sample_open_struct = OpenStruct.new(sample_hash)
      sample_open_struct.foo_key
    end
  end
end