0
votes
1answer
79 views

when would you wrap a service object with an interface? [duplicate]

I'm new to UT and some of the best practices and anti-patterns when writing testable code, made me think. I used to wrap any service object with interface. but I see many mocking frameworks can ...
3
votes
4answers
449 views

How to force “program to an interface” without using a java Interface in java 1.6

In java 1.8 they have wonderful new "default interface methods". In 1.6 how close can we come? The goal: keep clients (using code) from being able to tell that a class is not a java interface. If ...
7
votes
4answers
469 views

“Immutable” interfaces

I am confused about the notion of immutability. Consider the following structure of a simplistic calculator: Here are the interfaces: interface IOperationalInterface { int Sum(int a, int b); } ...
1
vote
1answer
99 views

Domain-specific Interfaces

Are there any real benefits of using interfaces over abstract classes in a domain model? Does anyone have any experience using interfaces in a domain model in a real project? From a technical ...
1
vote
2answers
120 views

Should an abstract class always abstract its methods to an interface?

I had learned sometime ago that abstract classes should always abstract their functions to an interface. So instead of having something like this - abstract class a{ public int i; public int ...
2
votes
2answers
251 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 { ...
1
vote
2answers
85 views

How specific should be an interface about its implementation details?

Perhaps I should have picked a better title, but anyway... Basically what to do with two or more implementations that have the same public interface, but they are meant for slightly different ...
3
votes
3answers
483 views

Why not apply Interface Segregation Principle to “extreme”

Providing that clients would typically consume just one method, though methods would be conceptually related, why not always apply the Interface Segregation Principle to the extreme and have [many] ...
2
votes
0answers
97 views

The inheritance argument of zope.interface (providedby vs isinstance)

What limitations does inheritance of an interface through an abstract base class present that are addressed by zope.interface? In the following talk given in 2010 by Jeff Rush about interfaces, at ...
1
vote
4answers
262 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, ...
2
votes
1answer
139 views

Interface hierarchy design for separate domains

There are businesses and people. People could be liked and businesses could be commented on: class Like class Comment class Person implements iLikeTarget class Business implements iCommentTarget ...
0
votes
2answers
135 views

Interface method signature not restrictive enough

I wrote a piece of code at my job sometime ago. While writting the code I wrote few interfaces who would allow me to add more flexibility and at that time I was also trying to understand OOP concept ...
13
votes
3answers
815 views

Why are interfaces more helpful than superclasses in achieving loose coupling?

(For the purpose of this question, when I say 'interface' I mean the language construct interface, and not an 'interface' in the other sense of the word, i.e. the public methods a class offers the ...
1
vote
3answers
263 views

Why are inheritance and interfaces restricted to instance members?

Disclaimer: I think the rules are almost the same in most OO languages, but since I'm most familiar with C# I'll be relating to this specific language. I think that the use of attributes and ...
3
votes
2answers
452 views

Implementing the Interface Segregation Principle

Does this IConvertible interface satisfy the Interface Segregation Principle (ie. the "I" in SOLID)? Here is the definition: public interface IConvertible { TypeCode GetTypeCode(); bool ...
2
votes
4answers
346 views

Understanding “programming to an interface”

I have come across the term "programming to an interface instead of an implementation" a lot, and I think I kind of understand what it means. But I want to make sure I understand it's benefits and ...
-1
votes
3answers
210 views

Regarding interfaces of classes in OOP

When one says "a class' interface": Does he/she refer to all of the get and set methods - or do they refer only to the methods' signatures and return types, without the inner implementation of these ...
-4
votes
1answer
159 views

what is the main utility of Interface in real world programming (OOPS) [duplicate]

what is the main utility of Interface. we know that we can implement dynamic behavior using interface but i guess it is not only the utility. so i like to know when we have to write interface and when ...
2
votes
1answer
151 views

Using partially implemented interfaces

Consider the following hierarchy in C++ notation: class A { public: virtual void doStuff()=0; virtual void doOtherStuff()=0; }; class B:public A { public: ...
4
votes
4answers
775 views

Which methods should be put in an interface and which in abstract classes?

I have seen many frameworks and modules and their standard they follow is like this UserInterface which have some predefined methods AbstractUserClass which implements userInterface Then ...
10
votes
12answers
2k views

Is “If a method is re-used without changes, put the method in a base class, else create an interface” a good rule-of-thumb?

A colleague of mine came up with a rule-of-thumb for choosing between creating a base class or an interface. He says: Imagine every new method that you are about to implement. For each of them, ...
2
votes
2answers
311 views

Class design for calling “the same method” on different classes from one place

Let me introduce my situation: I have Java EE application and in one package, I want to have classes which will act primarily as cache for some data from database, for example: class that will hold ...
0
votes
1answer
73 views

Inject specific classes or not

I have a TableSqlBuilder interface which has a method getCreateTableSql. This interface is used in some other class as follows: function createTable( $tableDefinition ) { $sql = ...
2
votes
0answers
142 views

ActiveX, OLE, COM explanation or informative links

I've been programming a lot with C# on Visual Studio and many minor/other languages, but I'm having a really hard time to get the grasp of ActiveX, OLE, COM interfaces. All I got is that they're like ...
1
vote
4answers
565 views

Explanation of the definition of interface inheritance as described in GoF book

I am reading the first chapter of the Gof book. Section 1.6 discusses about class vs interface inheritance: Class versus Interface Inheritance It's important to understand the difference between ...
9
votes
4answers
1k views

When to use interfaces (unit testing, IoC?)

I suspect I've made a schoolboy error here, and am looking for clarification. A lot of the classes in my solution (C#) - dare I say the majority - I've ended up writing a corresponding interface for. ...
4
votes
5answers
369 views

How does the concept of a class change when passing data to the constructor instead of method parameters?

Let's say we're making a parser. One implementation could be: public sealed class Parser1 { public string Parse(string text) { ... } } Or we could pass the text to the ...
5
votes
6answers
4k views

Is there any difference between interfaces and abstract classes that have abstract methods only?

Let's say we have an abstract class and let this class has only abstract methods. Is this abstract class different from an interface that has same methods only? What I am looking to know is if there ...
2
votes
1answer
302 views

How does dependency inversion principle work in languages without interfaces?

In C#/Java, the dependency inversion principle is often demonstrated by high-level classes that depends on an interface/abstraction (that it owns). Low-level classes will implement the interface, thus ...
0
votes
1answer
77 views

OO Design: hint EntityManager to preload some datasets

say I have an EntityManager that can read(PK) a dataset from the DB and return it. I have an application that will process multiple records, iterate over them and for each, use the EntityManager to ...
7
votes
3answers
182 views

Rules about the concreteness of method parameter types, return types and property types

Some time ago I read a kind of "rule of thumb" about the concreteness of method parameter types, return types and property types, but I just do not remember it. It said something about keep your ...
1
vote
1answer
152 views

Class inheritance and extra parameters

Im trying to create an SMS gateway .. I have a request coming in from a client (web form or API or database record) that I need to process and forward on to a 3rd Party API - or SMS provider. So that ...
3
votes
6answers
723 views

Can interface be not abstract?

Friend of mine said that not every interface is abstract. I haven't chance to discuss that with him but it get me thinking of not abstract interface in any type of language. Is there a non abstract ...
0
votes
2answers
227 views

Why to say, my function is of IFly type rather than saying it's Airplane type

Say, I have two classes: Airplane and Bird, both of them fly. Both implement the interface IFly. IFly declares a function StartFlying(). Thus both Airplane and Bird have to define the function, and ...
10
votes
7answers
3k views

Interfaces on an abstract class

My coworker and I have different opinions on the relationship between base classes and interfaces. I'm of the belief that a class should not implement an interface unless that class can be used when ...
9
votes
2answers
460 views

Is there an “ask for only what you need” interface principle?

I have grown into using a principle for designing and consuming interfaces that says basically, "ask for only what you need." For instance, if I have a bunch of types that can be deleted, I'll make ...
6
votes
3answers
489 views

What do you call an interface with no defining methods used as property setters

In ASP.NET and C# I've ran across this before. Your class needs to implement interface ISomething in order for something in the super class to supply something to you. I can't remember the details, ...
8
votes
9answers
1k views

What OO Design to use ( is there a Design Pattern )?

I have two objects that represent a 'Bar/Club' ( a place where you drink/socialise). In one scenario I need the bar name, address, distance, slogon In another scenario I need the bar name, address, ...
9
votes
4answers
818 views

Is it bad practice to use an interface for categorization only?

For example: Say I have classes A, B, C. I have two interfaces, lets call them IAnimal and IDog. IDog inherits from IAnimal. A and B are IDogs, while C is not, but it is an IAnimal. The important ...
3
votes
2answers
258 views

Is this a pattern? Proxy/delegation of interface to existing concrete implementation

I occasionally write code like this when I want to replace small parts of an existing implementation: public interface IFoo { void Bar(); } public class Foo : IFoo { public void Bar() { ...
15
votes
10answers
11k views

Why use an interface when the class can directly implement the functions? [duplicate]

Possible Duplicate: Why are interfaces useful? Like most faculty, my java faculty introduced interface without explaining or even mentioning its practical use. Now I imagine interfaces have ...
3
votes
4answers
307 views

As a tooling/automation developer, can I be making better use of OOP?

My time as a developer (~8 yrs) has been spent creating tooling/automation of one sort or another. The tools I develop usually interface with one or more API's. These API's could be win32, WMI, ...
0
votes
2answers
480 views

Is this bad design for a Shape interface?

I'm creating a vector editing program in C++, and I need a Shape interface which other concrete classes will implement. There is a requirement that no implementation inheritance is allowed. The design ...
12
votes
8answers
6k views

What is the point of an interface? [duplicate]

Possible Duplicate: When to use abstract classes instead of interfaces and extension methods in C#? What other reasons are there to write interfaces rather than abstract classes? This ...
6
votes
1answer
131 views

Private interfaces within a package

This is basically the same as Coding to interfaces, but played out in the real world of com when there are various engineering complexities such as immutability of published interfaces and ...
3
votes
3answers
336 views

Naming conventions for the only envisioned implementation of an interface

If you decide "Program to An Interface" trumps YAGNI and decide to create a supertype where you don't envision anything other than one obvious implementation - is there a convention for naming the ...
-5
votes
4answers
2k views

What is Interface in Java programming language? [duplicate]

Last week my lecturer was teaching us about interfaces in Java. However, I failed to understand her explanation that well. Does anyone have a good description, or explanation of Java interfaces, and ...
28
votes
9answers
4k views

Are abstract classes / methods obsolete?

I used to create a lot of abstract classes / methods. Then I started using interfaces. Now I am not sure if interfaces aren't making abstract classes obsolete. You need a fully abstract class? ...
11
votes
6answers
906 views

How to implement only a part of an interface

When developing in OOP, sometimes an interface / contract is given by a library that you cannot alter. Let's call this interface J. Now you have an object of class A that consumes objects that ...
4
votes
9answers
781 views

Does single inheritance limit what we can do with generalisation?

As a rule of thumb, generalisation is used only in specific circumstances. For example, when we can say that X is literally a subclass of Y. So, we can happily say that a Horse is a subclass of ...