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5
votes
3answers
1k views

is down-casting always bad?

At my company, we have many different "services" that work in parallel and send messages to each other using a common messaging system. All message objects are derived from a common generic object we ...
3
votes
3answers
479 views

Novel polymorphism - any reasons for this code?

As part of my work on a legacy C# application I've come across a novel (to me) use of an interface & concrete implementations. I can't think of any reason why you'd do the following, but I'm ...
2
votes
2answers
622 views

Questions about Polymorphism

So I understand the importance of Polymorphism, including how vital it is. But something I don't quite understand is what about the Constructor and any inherited Class the initial Base Class may ...
8
votes
4answers
877 views

Design pattern for polymorphic behaviour while allowing library separation

Let's say I have a hierarchy of Item classes: Rectangle, Circle, Triangle. I want to be able to draw them, so my first possibility is add a virtual Draw() method to each: class Item { public: ...
6
votes
4answers
5k views

Replacement for instanceof Java?

So I'm fairly new to programming in the real world (outside of academic projects) and have come across lots of posts saying that using instanceof is a bad thing to use to determine what class a ...
8
votes
8answers
2k views

Introducing polymorphism to new programmers

I've been teaching Java to a group of four people for about four months now. Prior to this, they've all had very limited or no other experience programming. We've gotten through basic control ...
1
vote
2answers
122 views

Interface extension

Suppose that I have an input stream interface, which defines a method for reading data. I also have a seekable interface which defines a method for seeking. A natural way of defining a input file is ...
1
vote
1answer
400 views

What does “polyadic” mean in the context of functional programming and type systems?

And how does it (or does not) correspond to "polymorphic"? Occasionally I see this notion like in: Implement and represent polyadic operations. I checked Wiktionary but it only gives a general ...
12
votes
6answers
563 views

OO Design, how to model Tonal Harmony?

I have started to write a program in C++ 11 that would analyse chords, scales, and harmony. The biggest problem I am having in my design phase, is that the note 'C' is a note, a type of chord (Cmaj, ...
5
votes
1answer
536 views

Abstract Factory Method and Polymorphism

Being a PHP programmer for the last couple of years, I'm just starting to get into advanced programming styles and using polymorphic patterns. I was watching a video on polymorphism the other day, and ...
0
votes
1answer
496 views

Java Dynamic Binding

I am having trouble understanding the OOP Polymorphic principl of Dynamic Binding ( Late Binding ) in Java. I looked for question pertaining to java, and wasn't sure if a overall answer to how dynamic ...
4
votes
2answers
308 views

Alternatives to type casting in your domain

In my Domain I have an entity Activity which has a list of ITasks. Each implementation of this task has it's own properties beside the implementation of ITask itself. Now each operation of the ...
3
votes
3answers
2k views

How to setup the c++ rule of three in a virtual base class

I am trying to create a pure virtual base class (or simulated pure virtual) my goal: User can't create instances of BaseClass. Derived classes have to implement default constructor, copy ...
4
votes
2answers
460 views

Reasons behind polymorphism related behaviour in java

I read this code somewhere class Foo { public int a; public Foo() { a = 3; } public void addFive() { a += 5; } public int getA() { ...
5
votes
13answers
1k views

Limitations of Polymorphism in statically typed languages

I program mostly in statically typed languages, like C++ and Java. A common strategy employed in languages like these to handle dealing with collections of objects which are related, but which need ...
4
votes
2answers
2k views

Is dependency injection by hand a better alternative to composition and polymorphism?

First, I'm an entry level programmer; In fact, I'm finishing an A.S. degree with a final capstone project over the summer. In my new job, when there isn't some project for me to do (they're waiting ...
0
votes
4answers
631 views

Objective-C message passing related queries

I am learning objective-C after having good knowledge of C/C++. I have 2 questions: Are Obj-C message passing and C++ vtable, two different ways of implementing polymorphism or Are they two very ...
2
votes
3answers
9k views

What is upcasting/downcasting?

When learning about polymorphism you commonly see something like this class Base { int prv_member; virtual void fn(){} } class Derived : Base { int more_data; virtual void fn(){} } What is ...
-9
votes
6answers
4k views

Function like C# properties?

I've been thinking about how C# properties work and could work. I know the purpose that C# properties were originally designed for, which is certainly useful. However instead in this question I'm ...
4
votes
1answer
2k views

implicit vs explicit interfaces

I think I understand the actual limitations of compile-time polymorphism and run-time polymorphism. But what are the conceptual differences between explicit interfaces (run-time polymorphism. ie ...
9
votes
5answers
702 views

Writing Testable Code vs Avoiding Speculative Generality

I was reading some blog posts this morning, and stumbled across this one: If the only class that ever implements the Customer interface is CustomerImpl, you don't really have polymorphism and ...
-1
votes
4answers
247 views

Polymorphism confusion

I have read once in a book about exception where "an object of type Exception can be an instance of any subclassof Exception". I kinda get it, but there's still confusion can anyone clarify me the ...
1
vote
1answer
628 views

Can the Abstract Factory pattern be considered as a case of polymorphism?

I was looking for a pattern/solution that allows me call a method as a runtime exception in a group of different methods without using Reflection. I've recently become aware of the Abstract Factory ...
12
votes
5answers
2k views

Is duck typing a subset of polymorphism

From Polymorphism on WIkipedia In computer science, polymorphism is a programming language feature that allows values of different data types to be handled using a uniform interface. From duck ...
46
votes
17answers
5k views

Is OO-programming really as important as hiring companies place it?

I am just finishing my masters degree (in computing) and applying for jobs. I've noticed many companies specifically ask for an understanding of object orientation. Popular interview questions are ...