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4
votes
2answers
59 views

Unused function parameters and polymorphism

I had a discussion with a co-worker about interface members having parameters that some implementations don't use. Say I have an interface interface IDoctor { string GetMedicalOpinion(Age age, ...
3
votes
2answers
161 views

Can a function be polymorphic and overloaded?

In Graham Hutton's book "Programming in Haskell", he defines a function to be polymorphic, if its type "contains one or more type variables". He then defines a function to be overloaded, if its type ...
4
votes
2answers
136 views

Understanding polymorphism and interface in Java

I'm reading though some notes. And I'm not understanding the following two statements. Polymorphism means that it is always the class of the actual object at run time that determines which method ...
-2
votes
1answer
74 views

Static Polymorphism explained

Here is a code I have got from here: class Deletor { public: virtual ~Deletor() {} }; template<typename T> class Base : public Deletor { public: int Run() { return ...
-1
votes
3answers
170 views

Modularity vs Polymorphism (OOD main concepts)

Booch gives 4 main concepts (principles) of OOD (see his book Object-oriented analysis and design with applications ): Abstraction Encapsulation Modularity Hierarchy Usually we encounter to these ...
1
vote
0answers
38 views

Polymorphically handle result of subtraction

I have an amount class which provides the minus method among others. The result of this operation is of course another amount. The question is how can I handle the three cases according to the signum ...
1
vote
2answers
121 views

C++ Parametric Polymorphism

In the wikipedia article on Parametric Polymorphism, is the following commentary on C++. Can anyone explain what it's referring to when talking about "ad hoc aspects"? (I think it needs a ...
1
vote
1answer
167 views

What is the DRY-est factory pattern to instantiate subtypes based on one of their properties' values?

Take the following class hierarchy: Client FacebookClient PinterestClient TwitterClient Each client must define a value for an enum property named ClientType (string property Url in the ...
0
votes
2answers
97 views

How to simulate method overloading in langs without such feature? [closed]

Langs like Java knows about true method overloading: class Overload { void demo (int a) { System.out.println ("a: " + a); } void demo (int a, int b) { System.out.println ("a and b: " + a ...
10
votes
3answers
300 views

How do you use duck typing in javascript without always checking for properties and methods?

I know javascript uses duck typing and at first I thought this would make polymorphism easy compared to strongly typed languages like C#. But now my functions that take arguments are littered with ...
2
votes
3answers
340 views

Should conditional logic be always coded via type system where possible?

I have a choice. Option 1: public class Sample { bool IsRelevant { get; set; } } Option 2: public class Sample { } public class RelevantSample : Sample { } Is there a clear well-known rule ...
2
votes
2answers
142 views

How is polymorphism better than two function calls in this example [ATM design]?

So I've finally started reading Designing Object-Oriented Software and my needle is stuck at a small but important point. I understand that the example I'm about to present might appear a bit out of ...
3
votes
1answer
201 views

Why throw a 'must implement this function' exception rather than making the function abstract?

In the Android support libraries here the destroyItem and instantiateItem functions throw an exception if they aren't overriden: 175 throw new UnsupportedOperationException( 176 ...
1
vote
1answer
76 views

What pattern should one use for multiple interpretations of the same data?

I have a set information that I am able to read in as raw data which corresponds to different physical quantities depending on which device provided that information. Every device contains the same ...
1
vote
1answer
83 views

“Is a” relationship or, in other words Inheritance

Say I define an interface IAnimal which has a pure virtual (abstract) method called eat like this: class IAnimal { virtual void eat(Food*) = 0; }; In the future I inherit form IAnimal and create ...
1
vote
1answer
41 views

Creating a specific table for shared columns among other tables (models)?

I'm creating a webapp that has a variety of models: Product, Category, ProductOption, etc. All of these models have a set of shared attributes: name, description, image, etc. There are two options I ...
0
votes
1answer
91 views

Is it good practice to assign an instantiated class to a static property in the same class?

I have code that was written by someone else that goes like this: On a ViewModel: public static ACertainViewModel Default { get; private set; } On the same ViewModel's constructor: public ...
1
vote
1answer
133 views

Accepted Patterns For Base Class with both Static And User-Defined Data Sources

I have a requirement to build a 'base' profile library (in C# - NET 4.5.2) for various different internal (technical) consumers. This profile consists of metadata fields that would be shared by a ...
2
votes
1answer
140 views

Implementing a series of independent Actions that are disparate but with common accessibility

I have a requirement to implement a type of AI for a project, the issue is that I am having trouble visualizing how the AI should actually be implemented. Essentially, I want the AI to be as dynamic ...
8
votes
3answers
251 views

Is it bad practice to make a subclass in name only for readability?

I have three sensors in a single package that all need to be calibrated which I will call sens1, sens2, and sens3. The calibration for sens1 and sens2 are identical, but the calibration for sens3 ...
1
vote
1answer
105 views

A little confused with virtual functions

Please see the following code: #include<iostream.h> #include<string.h> class father { char fname[20]; public: father() { strcpy(fname,"eshwarappa"); ...
1
vote
1answer
60 views

Polymorphism on repository interface for local and remote operations

I'm in the process of designing a facade ApiClient class that would abstract some CRUD operations between a local database and a remote one (through a REST web app). Said ApiClient class depends on 2 ...
2
votes
2answers
188 views

Haskell types for functions

I don't understand the answer to this question: Q: Can Haskell find a type for the function selfapply defined by: selfapply f = f f A: The function selfapply is not typeable in the simple ...
2
votes
1answer
142 views

Alternatives to #if when polymorphism doesn't seem possible

There are couple of places where #if seems to give you abilities that polymorphism doesn't: Conditionally specifying base class When a section contains code that is not recognised by a compiler on ...
128
votes
5answers
25k views

What exactly makes the Haskell type system so revered (vs say, Java)?

I'm starting to learn Haskell. I'm very new to it, and I am just reading through a couple of the online books to get my head around its basic constructs. One of the 'memes' that people familiar with ...
2
votes
1answer
132 views

Should I represent physical accessories of a system as classes in software?

I am redesigning a system comprised of a data-acquisition unit and a lot of different sensors (voltage sensor, angle sensor, pressure sensor, etc.). In the software domain model, there is a base ...
3
votes
3answers
471 views

Polymorphic template container: shared_ptr vs reference_wrapper

Assuming we have two classes: class A { ... } class B : public A { ... } Would it be better to write std::deque<shared_ptr<A> > container; or ...
0
votes
1answer
204 views

Protected properties vs protected getters

If I have an abstract Animal class with a $name property and constructor like this: abstract class Animal { protected $name; public function __construct($name) { $this->name = $name; ...
5
votes
1answer
166 views

How to use OO Design to Refactor a Library with Functions that are specific Product-aware

I have a class that acts as a library of functions for various products. To compute its data, the function currently needs to be aware of all product names. Depending on which product calls the ...
1
vote
2answers
4k views

Overriding methods by passing as argument the subclass object where the supertype is expected

I am just learning Java, and am not a practicing programmer. The book I am following says that when overriding a method, the argument types must be the same, but the return types can be ...
3
votes
2answers
265 views

Database design for polymorphic data

I have an application that needs to log communications with users over several different mediums: Email, SMS, Voice, Website Announcements, etc.. in a traditional database. I have considered 3 ...
2
votes
3answers
363 views

Inheritance in imperative programming

My first introduction to programming was Java, which was horrible so I learnt Actionscript3 which was nice... "The point is" OOP was my introduction to programming where by I went on to gain a career ...
1
vote
3answers
376 views

Why static members can't be abstract and don't implement polymorphism? [duplicate]

I'm a Java/C#/PHP developer, through my OOP programming experience I find myself asking the same question: Why static members can't be abstract and don't implement polymorphism especially in ...
0
votes
1answer
196 views

Is not being able to resolve a function call to its declaration a drawback of Polymorphism?

Consider a class that prints an "outline" table for a particular product line. Say you have several, A, B, C, D. The mechanism of the table generation is the same, but the data is different. I ...
2
votes
2answers
418 views

Is it possible to have Ad-Hoc polymorphism with runtime dispatch?

As I did understand, and as it's described here, ad-hoc polymorphism is limited to compile-time dispatch. That is, if we have a function that expects an argument that belongs to a typeclass, we must ...
3
votes
3answers
262 views

Why return back or assign to a supertype rather than the implementation type?

I have been doing a lot of reading about polymorphism, inheritance and typing (specifically how it applies to Java). I have seen some interesting examples, but not much explanation as to why. I.e.: ...
1
vote
1answer
2k views

Why overriding a static method does not result in polymorphism in java

Many say that we can not override a static methods. But we can override a static method. The question is, when we override a static method why it does not result in polymorphism ?
0
votes
1answer
149 views

Are there any programming languages that use strict evaluation that also have overloaded values?

Haskell supports overloaded values, where a single overloaded value can behave sort of like a superposition of values each with a different type. For example, here's a simple type class: class Truthy ...
2
votes
1answer
761 views

How do multiple levels of inheritance affect virtual function call overhead in C++?

I am considering using a class hierarchy with more than a single level of inheritance, where virtual member functions form a "chain", for example: struct Base { virtual void foo(); }; struct D1 : ...
1
vote
1answer
134 views

Ignoring the generic part of a type while an object is being passed

I have a message class that holds the name of a destination, and a generic variable acting as the message payload public class Message<T> { public string Destination public T Payload ...
1
vote
4answers
2k views

When to not use dynamic in C# [closed]

I'm making a class similar to the following: public class KeyValue { public readonly string key; public readonly object value; } Value could be of any object type as a result of this ...
2
votes
3answers
263 views

Is 'design with types first' ultimately the same as 'design with interfaces first'?

In Object Oriented Programming, we're taught to think in terms of Polymorphism (the idea that the implementation is decoupled from the interface - and that it makes sense to think of the interface ...
3
votes
1answer
220 views

Redundancy caused by polymorphism

I have two chat rooms, one has administration behaviour, and one doesn't. I have factored out all of the common code into a base chat room, but the AdministerChatroom behaviour I have pulled out into ...
17
votes
12answers
4k views

Is method overloading anything more than syntactic sugar? [closed]

Is method overloading a type of polymorphism? To me it seems like simply the differentiation of methods with the same name and different parameters. So stuff(Thing t) and stuff(Thing t, int n) are ...
3
votes
4answers
309 views

Is there a way to avoid type-checking in this scenario?

I have a class SuperClass with two subclasses SubClassA and SubClassB. I have a method in a different class which takes a SuperClass parameter. The method should do different things depending on the ...
1
vote
2answers
261 views

Is it an anti-pattern to use void* and enums to enable type-checking?

Say in a game engine, you have Objects that composited of different components. One of these is a RenderComponent which can be either a Mesh, a Sprite or a Light. Now, all these are vastly different ...
2
votes
2answers
301 views

Does it make sense to use interfaces if you don't have polymorphism?

Suppose I have distinct classes that have the same behavior, which can be represented like this: public interface Behavior { void operationA(); } public class ImplementerA implements Behavior { ...
2
votes
5answers
1k views

Classic inheritance problem?

I keep seeing the following pattern when people learn about OOP: Problem: How do I put objects of different but related types into a container? Solution: Inherit from a common base class. New ...
1
vote
4answers
461 views

Combinatorial explosion of interfaces: How many is too many?

I'm a relative newcomer to OOP, and I'm having a bit of trouble creating good designs when it comes to interfaces. Consider a class A with N public methods. There are a number of other classes, B, C, ...
0
votes
1answer
182 views

Clean way to use mutable implementation of Immutable interfaces for encapsulation

My code is working on some compost relationship which creates a tree structure, class A has many children of type B, which has many children of type C etc. The lowest level class, call it bar, also ...