Issue #20738 has been updated by mame (Yusuke Endoh). History. Long ago in Ruby, such a special value actually existed. It was `nil`. ```ruby # ruby 1.4.6 h = { 1 => 2 } p h #=> {1=>2} # This removes the key 1 h[1] = nil p h #=> {} ``` However, there were more and more cases where we want to treat `nil` as an ordinary value. Finally, `nil` has lost this speciality. Considering this history, the special value is not a good idea. ---------------------------------------- Feature #20738: Removing a specific entry from a hash literal https://bugs.ruby-lang.org/issues/20738#change-109773 * Author: ursm (Keita Urashima) * Status: Open ---------------------------------------- Sometimes I want to decide whether or not to add a particular entry to a hash depending on a condition. If the entire hash does not use nil, I can use Hash#compact. ```ruby { foo: 1, bar: bar? ? 2 : nil }.compact ``` But if I want to remove only a specific entry while leaving the other nil, it is somewhat cumbersome. I have to either assign the hash once and change it destructively, or use Hash#reject. ``` ruby h = { foo: 1, baz: nil } h[:bar] = 2 if bar? ``` ``` ruby { foo: 1, bar: bar? ? 2 : :drop, baz: nil }.reject {|_, v| v == :drop } ``` As a suggestion, how about a special value that indicates an invalid key for the hash? With this, the above example could be written like this: ``` ruby { foo: 1, bar: bar? ? 2 : Hash::DROP, baz: nil } #=> {foo: 1, baz: nil} ``` -- https://bugs.ruby-lang.org/