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

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1answer
64 views

serving up future-proof kinfolk - extensible contract interfaces [closed]

Ok, I have this human here, but what can it do, how would you discover its special abilities? And when you find out what kind of expert you've got then how would you actually make use of its unique ...
1
vote
5answers
960 views

The need for adding an interface to every class [duplicate]

My coworker and I are arguing very hard about this topic. He's thinking that every single class should have an Interface that the class implements (also Single-Implementations). He uses this design ...
1
vote
3answers
261 views

Coarse grained remote interface vs encapsulating business logic

I'm writing a Web Service that will be consumed by a Mobile client. The Mobile client has to make several chained requirements checks to determine whether the user may initiate a request, and if so ...
5
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6answers
5k 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
372 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 ...
2
votes
3answers
280 views

Implicit optimization versus explicit optimization

To explain what I mean, let me start with an example. Consider a deque that supports O(logn) concatenation with another deque and O(n) addition of n elements at one end. This dequeimplements a ...
6
votes
1answer
286 views

Term for a Class with Multiple Interfaces

Say I have a class that implements multiple interfaces. I pass the same instance around using a different interface, depending on what the consumer is interested in. I am trying to remember what this ...
0
votes
1answer
100 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 ...
4
votes
2answers
260 views

Should I make package private my DAO interfaces?

I have several DAO classes that implement an interface. In the other hand, I have Service classes that use those DAO implementations. So far all the DAO interfaces are public and I was thinking if ...
12
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5answers
2k views

What is the functional-programming alternative to an interface?

If I want to program in a "functional" style, with what would I replace an interface? interface IFace { string Name { get; set; } int Id { get; } } class Foo : IFace { ... } Maybe a ...
7
votes
3answers
202 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 ...
0
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2answers
1k views

1 Interface 2 Implementations and an EJB exception

In my JavaEE project I have an interface like this: @Local public interface DataAccess { ... } And two stateless beans implementing it: @Stateless public class DataAccess_Online implements ...
1
vote
1answer
164 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 ...
4
votes
1answer
224 views

Can a common interface be defined for Cartesian and Polar coordinate data?

I'm rewriting a set of file readers that a former-colleague of mine created that read raw-point data of XYZ (Cartesian) coordinates or RTZ (Polar) coordinates. Currently the data is stored directly in ...
5
votes
1answer
293 views

Why aren't there Dimension and Point interfaces?

I mean something along the lines of: public interface Dimensioned { int getWidth(); int getHeight(); } and public interface Positioned { int getX(); int getY(); } There are a ...
2
votes
3answers
121 views

Adding Methods In Addition to an Interface

Let's say I have ThingImpl and IThing. The former is an implementation of the latter, which is an interface. IThing has 1 method: do(arg1) Is it considered a hack/bad practice to add a method in ...
8
votes
3answers
2k views

Should I implement an interface directly or have the superclass do it?

Is there a difference between public class A extends AbstractB implements C {...} versus... public class A extends AbstractB {...} AbstractB implements C {...} I understand that in both cases, ...
1
vote
4answers
705 views

Switch interface implementation using configuration [closed]

We want to allow the same core service to be either fully implemented or, as other option, to be a proxy toward a client legacy system (via a WSDL for example). In that way, we have both ...
3
votes
7answers
636 views

What problems will I face if I remove the concept of interfaces from my code?

I have been programming for many years but I am still not comfortable with the concept of "Interfaces". I try to use interfaces but many times I don't see a mandatory use for it. I think this is ...
1
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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 ...
5
votes
2answers
829 views

How to create contracts in python

I am currently learning Python (from Java) and have a question on contracts. Example: an application defines an interface that all plugins must implement and then the main application can call it. ...
0
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0answers
151 views

Where are the Interface information stored?

I would like to know whether the information in an interface such as the variables which are final and the methods which are abstract and static would all live in method area ??? And what would be ...
1
vote
3answers
240 views

Should I use an interface when methods are only similar?

I was posed with the idea of creating an object that checks if a point will collide with a line: public class PointAndLineSegmentCollisionDetector { public void Collides(Point p, LineSegment s) { ...
1
vote
2answers
1k views

Adhering to a protocol and being a subclass at the same time?

In objective C, I have a situation where I would like to have an abstract protocol (interface) with 5 methods and 4 properties, but at the same time, I'd like to have a common implementation of 3 of ...
2
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1answer
195 views

Use of interfaces to ease rapid development/prototypes

Recently I've started to put almost all of my data structures into interfaces, and many of the classes that contain pieces of logic code as well, depending on how much work they are. I find that this ...
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, ...
3
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6answers
853 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 ...
3
votes
2answers
199 views

Developing JSON API for a Carpool Engine

I am developing a new set of API methods for carpooling/cab booking, so if a developer needs to develop an app or webportal for carpooling, he can call my JSON API. Basically making it easy for ...
16
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5answers
2k views

Use of keyword “Using” in C# interface

When I'm using C# to write some code and I define an interface using Visual Studio 2010, it always includes a number of "using" statements (as shown in the example) using System; using ...
6
votes
5answers
511 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 ...
4
votes
4answers
6k views

Instantiating Interfaces in C#?

I am reading/learning about interfaces in C# at the moment, and thus far I managed to understand how it differs from an abstract class. In the book I am reading the author explains that interfaces are ...
13
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4answers
485 views

Two interfaces with identical signatures

I am attempting to model a card game where cards have two important sets of features: The first is an effect. These are the changes to the game state that happen when you play the card. The interface ...
3
votes
4answers
8k views

Abstract class + Inheritance vs Interface

Hello fellow programmers, I am reading a book on C# and the author is comparing Abstract classes and Interfaces. He claims that if you have the following "abstract class:" abstract class ...
0
votes
2answers
228 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 ...
3
votes
2answers
2k views

Java - What methods to put in an interface and what to keep out

I'm designing a file handler interface: public interface FileHandler { public void openFileHandler(String fileName); public void closeFileHandler(); public String readLine(); public ...
4
votes
5answers
498 views

Should concrete classes avoid calling other concrete classes, except for data objects?

In Appendix A to The Art of Unit Testing, Roy Osherove, speaking about ways to write testable code from the start, says, An abstract class shouldn't call concrete classes, and concerete classes ...
5
votes
2answers
419 views

Function that requires many parameters

I have a problem related to this: Are there guidelines on how many parameters a function should accept? In my case, I have a function that describes a rounded rectangle. The caller specifies An ...
15
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10answers
3k views

Declaring interface in the same file as the base class, is it a good practice?

To be interchangable and testable, normally services with logic needs to have interface, e.g. public class FooService: IFooService { ... } Design-wise, I agree with this, but one of the things ...
9
votes
4answers
5k views

Should interfaces extend (and in doing so inherit methods of) other interfaces

Although this is a general question it is also specific to a problem I am currently experiencing. I currently have an interface specified in my solution called public interface IContextProvider { ...
11
votes
7answers
4k 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 ...
3
votes
1answer
10k views

Difference between spring setter and interface injection?

I know how constructor and setter injection works in spring. Normally I use interfaces instead of classes to inject beans using setter and I consider it as interface injection, but in case of ...
4
votes
3answers
144 views

What level of detail to use in an interface members descriptions?

I am extracting interfaces from some classes in .NET, and I am not completely sure about what level of detail of description to use for some of the interface members (properties, methods). An ...
9
votes
2answers
477 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 ...
8
votes
4answers
412 views

Use cases for “private” interfaces?

I was wondering if there was a valid use case for being able to properly define the specific internal properties and functions of a class in a way similar to how an interface defines the public ...
2
votes
1answer
604 views

Why this code create object as interface?

In am reading Spring in Action (3rd edition) and here a snippet from it: ApplicationContext ctx=new ClassPathXmlApplicationContext("springidol.xml"); Performer ...
6
votes
3answers
573 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, ...
5
votes
2answers
149 views

Using a openid in a “closed system”

I would like to publish a website for certain family members only. Simply put, like a mishmash of family photos and videos. I want it to remain private, however. I was considering using openid for ...
8
votes
4answers
3k views

Return interface or class

Suppose I have a method public List<User> GetBatchOfUsers(IEnumerable<int> userIDs) { List<User> users = new List<User>(); // some database stuff return users; } ...
13
votes
4answers
1k views

Is there a different usage rationale for abstract classes/interfaces in C++ and Java

According to Herb Sutter one should prefer abstract interfaces (all pure virtual functions) to abstract classes in C++ to decouple the implementation as far as possible. While I personally find this ...
77
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14answers
21k 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?