From: "john_firebaugh (John Firebaugh)" Date: 2012-11-08T03:25:02+09:00 Subject: [ruby-core:49052] [ruby-trunk - Feature #7297] map_to alias for each_with_object Issue #7297 has been updated by john_firebaugh (John Firebaugh). I reviewed my own use of Hash[], and in the majority of cases, I'm transforming both the key and value. So I would prefer a more flexible definition: module Enumerable # Associates keys with values and returns a Hash. # # If you have an enumerable of keys and want to associate them with values, # pass a block that returns a value for the key: # # %w( tender love ).associate &:capitalize # # => {"tender"=>"Tender", "love"=>"Love"} # # [1, 2, 3].associate { |i| [i * 2, i ** 2] } # # => { 2 => 1, 4 => 4, 6 => 9 } # # If you have an enumerable key/value pairs and want to associate them, # omit the block and you'll get a hash in return: # # [[1, 2], [3, 4]].associate # # => { 1 => 2, 3 => 4 } def associate(mapping = {}) if block_given? each_with_object(mapping) do |key, object| key, value = yield(key) object[key] = value end else each_with_object(mapping) do |(key, value), object| object[key] = value end end end end ---------------------------------------- Feature #7297: map_to alias for each_with_object https://bugs.ruby-lang.org/issues/7297#change-32578 Author: nathan.f77 (Nathan Broadbent) Status: Rejected Priority: Normal Assignee: Category: lib Target version: 2.0.0 I would love to have a shorter alias for 'each_with_object', and would like to propose 'map_to'. Here are my arguments: * It reads logically and clearly: [1, 2, 3].map_to({}) {|i, hash| hash[i] = i ** 2 } #=> {1 => 1, 2 => 4, 3 => 9} * Rubyists are already using 'map' to build and return an array, so it should be obvious that 'map_to(object)' can be used to build and return an object. * Given that 'each' and 'each_with_index' return the original array, I feel that the 'each_with_object' method name is slightly counterintuitive. 'map_to' might not be 100% semantically correct, but it's obvious that it will return something other than the original array. * Many people (myself included) were using inject({}) {|hash, el| ... ; hash } instead of 'each_with_object', partly because of ignorance, but also because 'each_with_object' is so long. 'map_to' is the same length as inject, and means that you don't have to return the object at the end of the block. * Only a single line of code is needed to implement the alias. Best, Nathan -- http://bugs.ruby-lang.org/