abstract

I’m trying to wrap up a two day beat down on Abstract methods and return type Covariance, I’ve already posted two similar questions and I am eternally grateful to the community for the info provided, I just need one last push to get to the finish line. Here is what I am trying to do: 2 abstract classes, RecruiterBase and CandidateBase, both have concreate implementations of RecruiterA and CandidateA. RecruiterBase has an abstract method to get all recruited candidates returning IQueryable. My implementation of RecruiterA overrides the GetCandidates() method to return IQueryable. public

I have a class which is supposed to be abstract. In one of it's abstract methods the return type may be an instance of class1,class2 or class3, depending on the class that's implementing the method. I'm wondering how should I declare the method in the abstract class. I thought about using dynamic typing, but I want the return type to be restricted to one of the 3 classes, not every type, and in addition I'm not sure I can override it so that in the inheriting class the return type will not match the return type in the abstract class. I'd be glad if you could help me with this, Tnx! Take a look

I am working on an exercise which asks me to take a base class Rodent and make it a pure abstract class. My understanding of a pure abstract class is that it acts as an interface and only contains pure virtual functions. Although this is an easy exercise I have a problem with the solution provided by the book: class Rodent { public: virtual ~Rodent() {cout << "Destroy rodent" << endl;} virtual void run() = 0; virtual void squeak() = 0; }; As you can see the author has added a dummy definition for the destructor. Does the adding of this definition not mean that this is an abstract class and not

abstract public class car { abstract void drive(); } As in the code snippet above, what exactly is the purpose of an abstract method in Java? From what I can gather, by definition, they aren't allowed to have bodies. When you make things implement the same abstract class, you are saying, these things are alike at a high level, but they vary in the particulars of how they do things. An abstract method is how you say, "Here's something that all the things that extend this class have to do, but they each get to specify how exactly they will do it." By declaring a method abstract you are not

With the following example I attempting to learn a few new to me concepts. abstraction polymorphic classes factory programming. boost serialization The nuances of how pointers behave are still something I am working to figure out. Here is a small program that I have written to show you the issue I am struggling to understand. When I unserialize the polymorphic object below I only get an object created from the default constructor. TodoFactory::retrieveATodo is not recreating the object from the serialized data. This is displayed by the output of "unserialzed command" in that function. Here is