Questions about interface related design considerations, such as programming to the interface.

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2answers
359 views

Programming against interfaces in Java

Supposing I have an interface Foo and a given implementation FooImpl. public class FooImpl implements Foo If I want to define a new operation on this class that depends on the particular ...
8
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3answers
6k views

Why does C# allow properties in interfaces?

In C#, the following code is valid interface I{ int property{get;set;} } Which doesn't make any sense to me. This seems to break one of the most important principles of interfaces: lack of ...
0
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3answers
148 views

Naming interfaces for persistent values

I have 2 distinct types of persistent values that I'm having trouble naming well. They're defined with the following Java-esque structure, borrowing Guava's Optional for the example and using generic ...
0
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0answers
30 views

Restructuring similar interfaces to one unified design

In my project, I have several types of Web API controllers (and their corresponding services and repositories). When I started out, I made an interface of a generic type that would describe the basic ...
11
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4answers
2k views

Is it permissible to use explicit interface implementation to hide members in C#?

I understand how to work with interfaces and explicit interface implementation in C#, but I was wondering if it's considered bad form to hide away certain members that would not be used frequently. ...
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3answers
255 views

Implements > extends, but what about variables?

It's preferable to write programs that depend on interfaces rather than on superclasses, but what when you want a class to have certain variables? Sometimes you want a class to implement a certain ...
29
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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? ...
0
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1answer
217 views

Android, using a Fragment to hold/edit complex object, accesible from any Activity

I'll do my best to describe the problem, but I'm still very new to several concepts that I think this problem requires to be solved (namely interfaces and threads). I should preface this by saying ...
0
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1answer
94 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
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1answer
207 views

Trying to get a better understanding of Interfaces

Im working on a small program and I thought i would use it as a chance to get a better understanding of things I haven't really used before, mainly Interfaces and Inheritance from base classes. ...
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4answers
1k 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 ...
4
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1answer
134 views

Handling interface segregation in C++

I'm designing a "view" handling system for a game. The goal is to be able to have different "views" that can be shown in sequence or stacked on-top of each other. For example, the initial splash ...
3
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3answers
218 views

Should I denote that a method satisfies an interface?

When writing a class which has ("satisfies") 1 or more interfaces, should I note somehow (e.g. in an XML comment, or with an attribute) that a particular method was added for one of the interfaces? ...
0
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1answer
171 views

Static methods vs Interface implementation

Here is my problem: I stared to create a e-commerce web sites info collector. So i created a parser for each site. The parser class is state less. got methods like: getItemPrice(WebElement page) ...
0
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2answers
141 views

How to organise and label methods, intended for debug?

I have a class System, which uses a bunch of other classes, to achieve a complex signal processing. In debugging System, one needs to observe the output signal for patterns. This is not achievable by ...
5
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3answers
246 views

Does it make sense to split up an existing multi-method interface into several single method interfaces just to take advantage of lambdas?

Say I have an existing callback interface that has multiple methods. To illustrate my point I use a callback the likes that you would see in code that performs some HTTP client operations: public ...
18
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4answers
12k views

Why were default and static methods added to interfaces in Java 8 when we already had abstract classes?

In Java 8, interfaces can contain implemented methods, static methods, and the so-called "default" methods (which the implementing classes do not need to override). In my (probably naive) view, there ...
3
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2answers
205 views

Are there alternatives to using an optional type in a multithreaded environment?

I'm making an MPMC queue in C++, and I would like to find out what the best interface for a try_dequeue method would be (I'm not concerned about its implementation). I'd like to provide a method which ...
0
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2answers
93 views

Possible design patterns for base function with possible additions

I have various interfaces i have to implement. Let's assume ITypeA, ITypeB. They have following methods: ITypeA Connect Disconnect GetData SetData ClearData ITypeB Connect Disconnect ...
0
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0answers
103 views

Pitfalls of combining dependant traits and exceptions in same file as interface in php

What are the potential pitfalls of combining related class like objects (interfaces, traits, custom exceptions) in the same source file? For code reuse and only loading what I need I always separate ...
78
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14answers
23k views

Do I need to use an interface when only one class will ever implement it?

Isn't the whole point of an interface to for multiple classes to adhere to a set of rules and implementations?
23
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8answers
2k views

Interface design where functions need to be called in a specific sequence

The task is to configure a piece of hardware within the device, according to some input specification. This should be achieved as follows: 1) Collect the configuration information. This can happen at ...
0
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1answer
105 views

Prepared statement alternatives for this middle-man program?

I have an program that is using a prepared statement to connect and write to a database working nicely, and now need to create a middle-man program to insert between this program and the database. ...
0
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1answer
160 views

How to generalize a classes that has identical function plus some additional function

I have some designing problems with my project. To illustrate my problem, I'll use the following two classes from my project. public class RAM_UserManagement{ private Map<int,User> userList; ...
11
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6answers
7k views

What are the differences between abstract classes, interfaces, and when to use them

Recently I have started to wrap my head around OOP, and I am now to the point where the more I read about the differences between abstract classes and interfaces the more confused I become. So far, ...
4
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1answer
138 views

Designing module interfaces

I'm studying software engineering and one thing I'm really trying to improve is my skill in software architecture. My question is quite broad, so I'll try to explain it with an example. Suppose you ...
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3answers
642 views

Make Return Type an Interface - Problem with Initialization

I would like to make the return type of my method an interface rather than a class for similar reasons stated in c# List or IList, however I am having trouble figuring out how to initialize the ...
36
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4answers
18k views

Why should I prefer composition over inheritance?

I always read that composition is to be preferred over inheritance. A blog post on unlike minds, for example, advocates using composition over inheritance, but I can't see how polymorphism is ...
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4answers
544 views

Should I put extension methods of an interface in the interface.cs file?

Imagine this set up: public interface IMass{ double Mass {get;} } public static class IMassExtension { public static double ToKg(this IMass massObject) { return massObject.Mass / ...
2
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1answer
110 views

How modularized should my interfaces be?

I stumbled upon a specific instance where it seems that modularity and simplicity are at conflict with each other. Usually that's not the case, so I was really unsure how to resolve it. Suppose I ...
7
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4answers
495 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
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1answer
118 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 ...
0
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1answer
378 views

Does it make sense to break fluid interface if a bad argument is passed?

If I chain some setters together and one of them does not return $this, then I will get a fatal error. But maybe that is a good thing. $object = new object(); ...
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2answers
139 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 ...
3
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3answers
546 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] ...
7
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2answers
308 views

How to hide AOP implementation dependency without breaking encapsulation?

I have the concept of a SlowLoading thing: public interface SlowLoading { boolean hasLoaded(); } I also have a component MyComponent: public interface myComponent{ void doSomething(); } My ...
40
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9answers
4k views

Programming for future use of interfaces

I have a colleague sitting next to me who designed an interface like this: public interface IEventGetter { public List<FooType> getFooList(String fooName, Date start, Date end) ...
2
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2answers
268 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 { ...
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2answers
93 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 ...
2
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0answers
153 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 ...
6
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4answers
567 views

Split up large interfaces

I'm using a large interface with about 50 methods to access a database. The interface has been written by a colleague of mine. We discussed this: Me: 50 methods is too much. It's a code smell. ...
0
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3answers
352 views

Why do APIs generally consist of interfaces? [duplicate]

I am starting out in Java API design and in reading existing code bases, I have found that most APIs consist of interfaces only with their implementations bundled in a different package. Having read ...
96
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19answers
53k views

Why are interfaces useful?

I have been studying and coding in C# for some time now. But still, I can't figure the usefulness of Interfaces. They bring too little to the table. Other than providing the signatures of function, ...
1
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2answers
301 views

Go-like interfaces + multi-methods make sense?

Thinking about the design of a potential new language, I wonder how related are the concepts of built a OO similar to GO interfaces and multi-methods (I get this from ...
1
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4answers
313 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, ...
1
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2answers
75 views

Creating an Interface To a Language's Standard Library?

In the process of learning test-driven development, I've been introduced to dependency injection and the use of interfaces, and have started using these concepts in my own PHP code in order to make it ...
5
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1answer
75 views

Designing communications for extensibility

I am working on the design stages of an application that will a) collect data from various sources (in my case that's scientific data from serial ports), keeping track of the age of the data, b) ...
0
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2answers
245 views

Java best practice Interface - subclasses and constants

In the case where a couple of classes implements an interface, and those classes have a couple of constants in common (but no functions), were should I put this constant ? I've had this problem a ...
3
votes
4answers
3k views

What are good reasons to use explicit interface implementation for the sole purpose of hiding members?

During one of my studies into the intricacies of C#, I came across an interesting passage concerning explicit interface implementation. While this syntax is quite helpful when you need to resolve ...
3
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2answers
154 views

Design for an interface implementation that provides additional functionality

There is a design problem that I came upon while implementing an interface: Let's say there is a Device interface that promises to provide functionalities PerformA() and GetB(). This interface will ...