From: jacobevelyn@... Date: 2020-07-10T16:09:49+00:00 Subject: [ruby-core:99112] [Ruby master Feature#16739] Allow Hash#keys and Hash#values to accept a block for filtering output Issue #16739 has been updated by jacobevelyn (Jacob Evelyn). sawa (Tsuyoshi Sawada) wrote in #note-5: > Includes a duplicate of #14788. I just want to note that this is a *more powerful* feature than what's proposed in #14788, because both the key and value would be available to the block. Eregon (Benoit Daloze) wrote in #note-4: > In general I think we avoid adding blocks to core methods, because indeed it's not clear if people expect #map, #select or #filter_map behavior, and it's so much clearer with the explicit call. That's fair! Would calling these methods `filter_keys`/`filter_values` or `select_keys`/`select_values` be more explicit? ---------------------------------------- Feature #16739: Allow Hash#keys and Hash#values to accept a block for filtering output https://bugs.ruby-lang.org/issues/16739#change-86487 * Author: jacobevelyn (Jacob Evelyn) * Status: Open * Priority: Normal ---------------------------------------- I often see code like the following: ``` ruby hash.select { |_, v| v == :some_value }.keys hash.keys.select { |k| k.nil? || k.even? } hash.select { |k, v| valid_key?(k) && valid_value?(v) }.values ``` Each of these code snippets must allocate an intermediate data structure. I propose allowing `Hash#keys` and `Hash#values` to accept optional block parameters that *take both key and value*. For example, the above code could be rewritten as: ```ruby hash.keys { |_, v| v == :some_value } hash.keys { |k, _| k.nil? || k.even? } hash.values { |k, v| valid_key?(k) && valid_value?(v) } ``` This behavior: 1. Does not break any existing code (since `Hash#keys` and `Hash#values` do not currently accept blocks). 2. Is very readable���it's obvious what it does at a glance. 3. Is more efficient than current alternatives. 4. Is more concise than current alternatives. 5. Is flexible and useful in a variety of scenarios, because the block has access to both key and value (unlike the behavior proposed in #14788). -- https://bugs.ruby-lang.org/ Unsubscribe: