Ruby 2.3.0 introduced a method called dig on both Hash and Array. name = params.dig(:company, :owner, :name) It returns nil if the key is missing at any level. If you are using a version of Ruby older than 2.3, you can install a gem such as ruby_dig or hash_dig_and_collect, or implement the functionality yourself: module … Read more
Convert the key from a string to a symbol, and do a lookup in the hash. hash = {:key1 => “value1”, :key2 => “value2”} k = ‘key1′ hash[k.to_sym] # or iow, hash[:key1], which will return “value1” Rails uses this class called HashWithIndifferentAccess that proves to be very useful in such cases. I know that you’ve … Read more
Revisited, August 2014 Prompted by Arnaud Bouchez in a recent comment, and in view of other answers and comments, I acknowledge that the original answer needs to be altered or for the least qualified. I left the original as-is, at the end, for reference. First, and maybe most important, a fair answer to the question … Read more
EDIT: System.HashCode has now been released. The recommended way of creating hashcodes is now this: public override int GetHashCode() { return HashCode.Combine(fieldA, fieldB, fieldC); } System.HashCode.Combine() will internally call .GetHashCode() on each field, and do the right thing automatically. For very many fields (more than 8), you can create an instance of HashCode and then … Read more
I have presented that move in “Why doesn’t Git use more modern SHA?” in Aug. 2018 The reasons were discussed here by Brian M. Carlson: I’ve implemented and tested the following algorithms, all of which are 256-bit (in alphabetical order): BLAKE2b (libb2) BLAKE2bp (libb2) KangarooTwelve (imported from the Keccak Code Package) SHA-256 (OpenSSL) SHA-512/256 (OpenSSL) … Read more
If I understand the goal, then you should be able to pass in the parent to your save method. For the top level, it will be nil. The following shows the idea where puts is used as a place holder for the “save”. def save_pair(parent, myHash) myHash.each {|key, value| value.is_a?(Hash) ? save_pair(key, value) : puts(“parent=#{parent.nil? … Read more
The architect means that get and containsKey have the same costs and may be accumulated into one check: Integer val = map.get(c); if (val != null) { … } else { … } But I wonder why the architect is only concerned about that, as there are more things to improve: Refer to objects by … Read more
Options hash is a nice concept enabled by a feature of ruby parser. Say, you have a method with some required arguments. Also you may pass some optional arguments. Over time you may add more optional arguments or remove old ones. To keep method declaration clean and stable, you can pass all those optional arguments … Read more
There is already a method in ActiveSupport that does this. [‘an array’, ‘of active record’, ‘objects’].index_by(&:id) And just for the record, here’s the implementation: def index_by inject({}) do |accum, elem| accum[yield(elem)] = elem accum end end Which could have been refactored into (if you’re desperate for one-liners): def index_by inject({}) {|hash, elem| hash.merge!(yield(elem) => elem) … Read more