It would be great, if there were such feature that allows to create function by its name.

For example if we have variable var- the instance of class ClassName, and if we type name.someNonExistentFunction() (where someNonExistentFunction doesn't exist) and call refactoring menu on the word someNonExistentFunction we will be possible to add method someNonExistentFunction() to the class ClassName, what is rather convenient.