Using inject to take two arrays and use them to populate a hash

gistfile1.rb

@required_keys = [:email_address,:subject]
@optional_keys = [:email_from]
@params = {:email_address=>"test@test.com", :subject=>"email subject", :email_from=>"hi@test.com", :extra=>"not used"}

all_params = (@required_keys + @optional_keys).inject({}) do |result, element|
  result[element] = @params[element]
  result
end
=> {:email_address=>"test@test.com", :subject=>"email subject", :email_from=>"hi@test.com"}