Questions tagged [interfaces]

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

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3answers
538 views

How to decide, should I put methods to abstract class or to interface?

I'm writing an app it needs to have generic registration step item. It needs to be able to do some specific things (I use interface for that) and it needs to be a visual element (of Xamarin. It doesn'...
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1answer
874 views

Factory Design Pattern Implementation with multiple interfaces and base class

I know it is lot of code. But I am trying to understand the concept of Factory pattern with interfaces and base class. I have a base class of Car that implements an interface which will be implemented ...
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3answers
266 views

Should we inherit from base class and implement interface in this scenarios?

I am new to object oriented design and learning about interfaces and design patterns. In this example, I am trying to create class for cars. My question: Is it good practice to use base class and ...
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15answers
17k views

Should we design our code from the beginning to enable unit testing?

There's a debate going on in our team at the moment as to whether modifying code design to allow unit testing is a code smell, or to what extent it can be done without being a code smell. This has ...
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3answers
319 views

What would be the downsides of creating a derived interface of interface?

Would there be any downsides of creating sub-interfaces for virtual member functions that have different parameter types? A drawing of this is shown in the image attached. Apple and Orange do not ...
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0answers
29 views

Rely only on status or provide response explicitly? - SOA -

I am developing a set of SOA services where the backends (mainly stored procedures in the DB) sometimes return only status code as response (ex: an operation to cancel a ticket, the SP for this ...
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2answers
204 views

Which option is good in terms of software design?

I have one request interface IRequest and two classes ClientAddress and ClientOrder are implementing it. The same design is followed for Response with inteface IResponse and classes ...
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2answers
92 views

How are settings structured when they can be configured in diffferent ways?

Suppose of this question the following: I'm in full control of this project I'm writing a media player Obviously, a media player will allow a user to adjust the volume, so I might have a class that ...
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1answer
89 views

add new class that implement base interface but need one more parameter

I have few strategy class that calculate ranking. Those class implements interface with method scoreUpdates. Method scoreUpdates take two parameters( winners and lossers). Now i need add new ...
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3answers
2k 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 ...
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3answers
846 views

Interface properties implementation

As the code below, class Foo1 implements interface IFoo, which has a property of IData. public interface IFoo { public IData Data { get; set; } } public interface IData { ... } public class ...
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2answers
156 views

Does it make sense to implement a Class Factory design in an RPG Character Creation module

I'm a self-taught Engineer, a beginner in Java and I am trying to create a Dungeons and Dragons character creation module for a bigger game to solidify my understanding of core concepts while learning ...
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3answers
208 views

How to structure a set of classes that deal with external APIs for maximum testability?

I'm developing a set of classes designed to communicate with external APIs, and I'm running into trouble with how to properly structure everything for proper loose coupling and unit testing. ...
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5answers
516 views

What core principles would you want in a library?

Theres talk about what syntax and feature you like in a programming language; i'll now ask what core principles or feature would you like in a library in your favorite (or any) language? An example ...
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1answer
105 views

Handling multiple game modes with a game controller

I have a basic GameController with a finite state machine to handle game logic. I'm adding game modes and coming across problems cleanly implementing them. The core functionality of the game stays ...
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2answers
87 views

In some IOC contexts, could constructor of polymorphic immutable object be required in its interface?

Generally, constructors in an interface are considered as being an anti-pattern. Some languages even don't allow that. Then I don't understand how we're supposed to deal with polymorphic immutable ...
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1answer
120 views

Is it a good design to create an interface that inherits from multiple interfaces to reduce the amount of dependencies of a client?

I was refactoring an application to respect SOLID principles. When I was applying interface segregation I found the following case: interface A { void methodA(); void methodA2(); } ...
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4answers
1k views

Avoiding vtable pointers in objects in C++

In my previous question, it was highlight that implementations of C++ such as GCC must store a vtable pointer in every copy of a class for each parent class which has a virtual function. So a class ...
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5answers
375 views

How to avoid the continuous downcasting in this case?

I have an abstract class Dog and multiple subclasses (Beagle, Labrador, Bulldog...) extendig it. I have a DogHouse that can store a Dog. My problem is that when I put for example a Beagle into a ...
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1answer
1k views

Using generics on interfaces when implementation is not generic

Is it acceptable practice to put generics on an interface when the implementation will not be generic? Lets say that my project will have many classes that read data from the database. I may make a ...
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2answers
138 views

How can I force an object that respects an interface to output a certain data type / structure with its functions?

This is exactly my code, I'm just stripping out everything that isn't needed: First of all, I met this issue a lot of times and something tells me that it's something to do with PHP itself and "data ...
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2answers
194 views

Complex interfaces in multilayer project

In my C# project I need to swap data providers in the future so I have created interfaces to build future providers off of. But this is the first time I have worked with interfaces that are "complex" ...
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6answers
2k views

Coding to Interfaces vs Abstract Inheritance

Inheritance vs coding to an interface is something I have wondered with respect to proper architecture design but actually have not run into an problems when using abstract inheritance over coding to ...
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1answer
241 views

Can (Java) Interfaces be referred to as APIs? [duplicate]

I am trying to understand what exactly an API is. From my current understanding, an API (Application Programming Interface) is a contract provided by a software instance, that guarantees a defined ...
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2answers
56 views

Interface name for time-based classes

I'd like to document that code encapsulated in a class is "time-based" in a Java-like language – the code behaves differently based on what time it is currently. To make it testable, it would read ...
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5answers
390 views

Information Hiding v.s. Static Type Safety

I'm working on a project with others and we have a discussion about information hiding and static type safety. Our scenario is described below. Language: C++11 Scenario: We want to create a tree-...
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2answers
148 views

How to handle state of an object? And how to enrich the state transition logic?

I am designing a class that has a state. I wonder if I should expose that state in the interface in view of allowing a decorator to enrich the state transition logic. Shall my design expose ...
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5answers
2k views

Everything has an Interface [duplicate]

Possible Duplicate: Do I need to use an interface when only one class will ever implement it? I am taking over a project where every single real class is implementing an Interface. The vast ...
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1answer
69 views

What to choose, ioctl-like interface or a set of distinct methods?

I am implementing a messaging protocol between nodes on a network and i am wondering how to expose the messaging system interface to the programmers. The messaging protocol supports a set of commands ...
3
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1answer
159 views

Repository that performs API calls internally - DDD

Please note: although my question relates to DDD, I am also interested in this from an architectural and OO design perspective. This question may also be a simple case of CQRS and/or interface ...
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1answer
116 views

Can a class represent two implementations?

I'm unsure about several things: I have a class that implements a NotificationDispatcher interface. This class I named WhatsappNotificationDispatcher, another implementation goes by ...
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1answer
189 views

to ISP or not to ISP?

I've got a design problem, and I figure it's not something totally uncommon so there must be some good practices out there. I have 2 domain entities: Process and Task. A Process is essentially a list ...
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1answer
90 views

An interface for designing Arduino code

Often I want Arduino board to control several peripherals. Writing program for all of them in one document using #define SOME_PIN 4 constructions seems pretty inconvenient to me. Especially in such a ...
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3answers
519 views

What is the name of this pattern (if any)?

There's a sort of pattern that I've sort of stumbled myself into "discovering" that seems extremely useful, but I've never seen it described before. It's sort of a way of achieving inheritance through ...
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3answers
472 views

Decoupled design using static interfaces

Now first I want to mention that I am not quite sure what is the term describing the issue at hand but I hope that I can illustrate it with some code. Problem: A shared class library defines an ...
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1answer
60 views

What to specify as interfaces in component diagrams

I am following the textbook Object oriented software specification using UML, patterns and Java (3rd edition) and I am defining interfaces between system components (subsystems). But I encountered a ...
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1answer
82 views

Would you implement an interface to connect to a database?

I found in a book (Learning PHP Design Patterns, Chapter 2, page 25) a text explaining the importance of interfaces in OOP design. The author ended up by giving this example: <?php interface ...
2
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1answer
239 views

Abstraction for Account transactions and balance

We have 10 applications which updates account balance table, without logging credit/debit line transactions (not sure why). They all have the pretty much same SQL Statement. In order to get out of ...
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5answers
4k views

Using Func instead of interfaces for IoC

Context: I am using C# I designed a class, and in order to isolate it, and make unit testing easier, I am passing in all its dependencies; it does no object instantiation internally. However, instead ...
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5answers
893 views

Newbie question: Should all class public methods come from an interface?

I'm currently learning about TDD techniques, one of the suggestion is to test only public methods and skip the private ones. I have also been reading about Mocking. If I want to mock a certain method, ...
4
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4answers
258 views

Should custom exceptions live with the interface or the implementation?

I have an interface IMyService in a class library. I have an implementation of this interface MyService in a separate class library. MyService may raise a custom exception CustomException. Should ...
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5answers
4k views

Does it make sense to define an interface if I already have an abstract class?

I have a class with some default/shared functionality. I use abstract class for it: public interface ITypeNameMapper { string Map(TypeDefinition typeDefinition); } public abstract class ...
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3answers
204 views

Implementing interface using class members

This was just a question I was wondering about in terms of best practice. I am writing a small C++ program that uses an interface to implement a function. In the class that uses the interface (i.e. ...
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7answers
76k views

When to use abstract classes instead of interfaces with extension methods in C#?

"Abstract class" and "interface" are similar concepts, with interface being the more abstract of the two. One differentiating factor is that abstract classes provide method implementations for derived ...
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10answers
98k 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 a ...
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2answers
194 views

Use case for interface

While going through some lecture video on interface. I noticed If we don't know about implementation, just requirement specification then go for interface. What can be the scenario? Though I've ...
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1answer
133 views

Whether to replace mutually exclusive but poorly related properties with an interface

A few years ago I designed a class which had two properties. The two classes ChildA and ChildB had a rich protocol with many properties and methods, but were only distantly related in my model. They ...
27
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2answers
4k views

Implementation of pure abstract classes and interfaces

Although this isn't mandatory in the C++ standard, it seems the way GCC for example, implements parent classes, including pure abstract ones, is by including a pointer to the v-table for that abstract ...
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3answers
2k views

C# How to avoid duplicate code with interfaces where objects have the same behaviour

So a simple example i have: public interface IFollow{ Transform Target {get;} void LateUpdate(); } public A : Monobehaviour , IFollow { public Transform Target {get; set;} public void ...
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8answers
26k views

Default vs Impl when implementing interfaces in Java

After reading Should package names be singular or plural? it occurred to me that I've never seen a proper debate covering one of my pet peeves: naming implementations of interfaces. Let's assume ...