Issue #20317 has been updated by Dan0042 (Daniel DeLorme). May I ask what is the use case for this? The only reason I can think to undefine `allocate` is if you want to allow only a single instance of the class, and in that case `include Singleton` should do the job fine I think. ---------------------------------------- Feature #20317: Removing the `allocate` method should cause `new` to fail https://bugs.ruby-lang.org/issues/20317#change-107123 * Author: tenderlovemaking (Aaron Patterson) * Status: Open ---------------------------------------- When you remove the `allocate` method from a class the you can't allocate the class via the `allocate` method. However, you _can_ allocate the class via the `new` method: ```ruby class Foo; end Foo.singleton_class.undef_method(:allocate) begin Foo.allocate # doesn't work, of course rescue NoMethodError end begin Class.instance_method(:allocate).bind_call(Foo) # also doesn't work rescue TypeError end Foo.new # works? ``` I think that when we remove the `allocate` method, the `new` method should also fail as there is no `allocate` method for `new` to call. -- https://bugs.ruby-lang.org/