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

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4
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1answer
229 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
324 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 ...
1
vote
3answers
244 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) { ...
2
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3answers
122 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
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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
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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 ...
3
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7answers
637 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 ...
5
votes
2answers
876 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. ...
3
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6answers
905 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
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0answers
158 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 ...
2
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2answers
258 views

Need some advice on CLI design, I need to provide simple but powerful command line options

I am writing a utility that runs on RHEL5 command line. I need my command line options to be simple but powerful. I looked at the various UNIX utilities to get an idea of how simple command line ...
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 ...
3
votes
2answers
205 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 ...
4
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5answers
504 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 ...
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
542 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 ...
13
votes
4answers
505 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 ...
0
votes
2answers
229 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
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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 ...
5
votes
2answers
426 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 ...
18
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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
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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 { ...
42
votes
6answers
11k views

What is the point of having every service class have an interface? [duplicate]

At the company I work at, every service class has a corresponding interface. Is this necessarily? Most of these interfaces are only used by a single class and we are not creating any sort of public ...
4
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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
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2answers
484 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 ...
13
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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 ...
6
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3answers
611 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, ...
2
votes
1answer
626 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 ...
5
votes
2answers
151 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 ...
9
votes
4answers
1k 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 ...
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; } ...
2
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7answers
1k views

Architectural patterns for interaction beyond MVC? [closed]

We all know the venerable Model-View-Controller pattern used to design interaction [mostly] with human users. It is the de-facto standard in OOP environment. What are some other architectural ...
4
votes
2answers
596 views

Storing IEnumerable as instance variable - is it a code smell to expect it to change?

I have something that works like a fixed size list - it's actually called FixedSizeStack<T> in my program. I will use it to represent the X last occured events. This event list will then be ...
8
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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, ...
1
vote
1answer
213 views

The design of a generic data synchronizer, or, an [object] that does [actions] with the aid of [helpers]

I'd like to create a generic data-source "synchronizer," where data-source "types" may include MySQL databases, Google Spreadsheets documents, CSV files, among others. I've been trying to figure out ...
5
votes
4answers
403 views

Passing compound object for parameters

I have different data modules, which take a couple of parameters from a configuration list. Do you think it's ok to pass a configuration object as a whole module1(config) and let the module pick what ...
3
votes
2answers
298 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() { ...
3
votes
2answers
1k views

Is it a good programming practice to have a class with several .h files?

I suppose the class have several different interfaces. Some it shows to some class, some it shows to other classes. Are there any good reason for that? One thing I can think of is with one .h per ...
17
votes
10answers
15k 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
1k views

How can I explain C# interfaces, and constructors to a 8 years old kid?

How can I explain C# interfaces and constructors to a 8 years old genius kid?
6
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3answers
1k views

Checking preconditions or not

I've been wanting to find a solid answer to the question of whether or not to have runtime checks to validate input for the purposes of ensuring a client has stuck to their end of the agreement in ...
1
vote
6answers
445 views

Interfaces: profit of using

First of all, my ubiquitous language is PHP, and I'm thinking about learning Java. So let me split my question on two closely related parts. Here goes the first part. Say I have a domain-model ...
0
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0answers
2k views

Teaching java interfaces to absolute beginners: What is a good example? [duplicate]

Possible Duplicate: Explaining interfaces to beginning programmers? I searched on stackoverflow and here for a good example to teach java interfaces in a beginners class. I found the ...
14
votes
5answers
2k views

How do you evolve & version an interface?

Say you have an interface IFoo: public interface IFoo { void Bar(string s); int Quux(object o); } In version 2 of your API, you need to add a method Glarg to this interface. How do you do ...
0
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2answers
539 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 ...
9
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5answers
3k views

Interface and Inheritance: Best of both worlds?

I 'discovered' interfaces and I started to love them. The beauty of an interface is that it is a contract, and any object that fulfills that contract can be used wherever that interface is required. ...
4
votes
1answer
2k views

implicit vs explicit interfaces

I think I understand the actual limitations of compile-time polymorphism and run-time polymorphism. But what are the conceptual differences between explicit interfaces (run-time polymorphism. ie ...
0
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5answers
1k views

Why does the use of interface-based programming appear to be limited to behaviour?

I have been doing a little thinking about inheritance vs. realization vs. composition. I am not about to post the whole detail here. So I was wondering, when we are not talking about creating ...
14
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8answers
10k 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
137 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 ...