I have a factory class to build objects of base class B. The object (D) that uses this factory received a list of strings representing the actual types. What is the correct implementation:

1. the factory receives an Enum (and uses switch inside the Create function) and D is responsible to convert the string to Enum.
2. the factory receives a string and checks for a match to a set of valid strings (using ifs')
3. other implementation i didn't think of.