0
votes
1answer
66 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 ...
2
votes
3answers
317 views

What is a good design for a method that can return several logically different results?

The question title is probably too abstract, so let me provide a particular example of what I have in mind: There is a webservice that encapsulates a process of changing passwords for users of a ...
4
votes
1answer
74 views

Keep or discard tests that use methods now private [duplicate]

When writing object-oriented code from scratch, I try to follow these steps: Write a test that fails. Write a function that makes the test pass. When enough tests and functions are complete, ...
1
vote
3answers
177 views

Sequence diagrams and the Implementation

In the design phase we create UML Sequence diagrams (in OOD). My understanding is that after creating an Use Case diagram if we need to show further information in terms of time sequence of events of ...
1
vote
1answer
136 views

How to structure a program into classes [closed]

So after a while of working in programming field I still haven't figured it out how exactly should programs be structured, in a large set I mean. Which I think it's also because of working in an ...
1
vote
4answers
217 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
vote
1answer
87 views

Liskov substitution principle with abstract parent class

Does Liskov substitution principle apply to inheritance hierarchies where the parent is an abstract class the same way if the parent is a concrete class? The Wikipedia page list several conditions ...
1
vote
7answers
633 views

Significant amount of the time, I can't think of a reason to have an object instead of a static class. Do objects have more benefits than I think? [closed]

I understand the concept of an object, and as a Java programmer I feel the OO paradigm comes rather naturally to me in practice. However recently I found myself thinking: Wait a second, what are ...
3
votes
3answers
290 views

Infinite loop with a singleton - does this type of issue have a name?

I ran into an unusual error while working on my project. To better learn from and remember it, I'd like to know if this type of error has a name or some definition. (The error itself OutOfMemoryError ...
1
vote
1answer
44 views

Handling Types for Real and Complex Matrices in a BLAS Wrapper

I come from a C background and I'm now learning OOP with C++. As an exercise (so please don't just say "this already exists"), I want to implement a wrapper for BLAS that will let the user write ...
1
vote
4answers
255 views

“Collection Wrapper” pattern - is this common?

A different question of mine had to do with encapsulating member data structures inside classes. In order to understand this question better please read that question and look at the approach ...
2
votes
1answer
190 views

Best practice to collect information from child objects

I'm regularly facing following pattern: public abstract class BaseItem { BaseItem[] children; // ... public void DoSomethingWithStuff() { StuffCollection collection = new ...
5
votes
5answers
596 views

Should I always encapsulate an internal data structure entirely?

Please consider this class: class ClassA{ private Thing[] things; // stores data // stuff omitted public Thing[] getThings(){ return things; } } This class exposes the ...
4
votes
3answers
329 views

Inheritance vs containment while extending a large legacy project

I have got a legacy Java project with a lot of code. The code uses MVC pattern and is well structured and well written. It also has a lot of unit tests and it is still actively maintained (bug fixing, ...
3
votes
1answer
161 views

Does this Decorator implementation violate the Liskov Substitution Principle?

Please consider the following implementation of the Decorator design pattern: WordBank objects store strings and return them to the client through the method getWords(). The decorator class, ...
2
votes
0answers
120 views

How does a search functionality fit in DDD with CQRS?

In Vaughn Vernon's book Implementing domain driven design and the accompanying sample application I found that he implemented a CQRS approach to the iddd_collaboration bounded context. He presents ...
1
vote
1answer
119 views

From a DDD perspective is a report generating service a domain service or an infrastructure service?

Let assume we have the following service whose responsibility is to generate Excel reports: class ExcelReportService{ public String generateReport(String fileFormatFilePath, ResultSet data){ ...
6
votes
3answers
289 views

How to adhere to the open-closed principle in practice

I understand the intent of the open-closed principle. It's meant to reduce the risk of breaking something that already works while modifying it, by telling you to try to extend without modifying. ...
1
vote
1answer
78 views

Using a list of tuples vs a list of custom objects

I have a situation where I have several text documents and I want to create a list that contains the words in those documents. But I also need to record several properties of each word. These ...
2
votes
2answers
210 views

What do I gain by using the Strategy pattern in this case?

I wrote a program with Java that plays simple music. Currently chords have only one way ('strumming pattern') to be played. I want to expand this and create different 'strumming patterns' that chords ...
0
votes
1answer
83 views

MVC: Where should I store interchangeable algorithms used by the Model (whose names also need to be accessible to the View)?

Please consider a program, where the user chooses an algorithm from a list, and the Strategy pattern is utilized to set this algorithm as the model's operation. For example, an image procession ...
6
votes
2answers
443 views

MVC: my controller seems useless half of the time. Is this a problem?

Often when I design a program with MVC, the controller is useless half of the time. What I mean is this: something happens on the view (e.g. a button click). The view then notifies the controller. ...
0
votes
2answers
163 views

Is often using int constants as parameters in communication between objects considered bad design?

An app I'm working on is designed with MVC. The components often interacts with each other by passing int constants, which then have to be interpreted with if statements. I'm wondering if this is ...
4
votes
4answers
409 views

MVC: Does the Controller break the Single Responsibility Principle?

The Single Responsibility Principle states that "a class should have one reason the change". In the MVC pattern, the Controller's job is to mediate between the View and the Model. It offers an ...
2
votes
2answers
121 views

MVC: Controller often simply delegates to Model when notified by View of GUI events. Is this reasonable?

Since I learnt about MVC, I used it for every app I made (which is arguably not the best idea, but that's not the topic of this question). All of them small, 1000 LoC apps. I am using Java and Swing ...
1
vote
1answer
170 views

Practical programming according to the Dependency Inversion Principle

What the Dependency Inversion Priciple implies in practice is that in a system, high level components should depend on abstractions of the low level components (instead of on the low level components ...
1
vote
4answers
505 views

Is it considered 'reasonable' to implement a major part of a program largely by subclassing a library class? [closed]

I'm planning to implement a word processor using Java, and Swing for the GUI. I was thinking how I can implement the text area where the user types the text. My idea was to subclass JTextArea. It ...
0
votes
1answer
144 views

UML class diagram - instantiation dependency relationship: who depends on who? [duplicate]

I did some reading on the <<instantiate>> relationship in UML class diagrams. It's a dependency relationship where one side depends on the other. However, I'm not sure who depends on who: ...
13
votes
3answers
649 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 ...
3
votes
2answers
389 views

Aren't decorators easily breaking the ISP?

"The Interface-Segregation Principle (ISP) states that no client should be forced to depend on methods it does not use." The decorator pattern is a design pattern to decorate a method of a class. For ...
3
votes
1answer
190 views

OO design choice and single responsibility principle

I'm currently refactoring an application which periodically downloads content from various sources (http, ftp, sql, etc). There is a schedule which controls the times during which the application can ...
1
vote
2answers
195 views

Using the Decorator pattern to add public methods to an object

The Decorator pattern is usually used to extend the functionality of an object by extending one of it's current methods. To illustrate, please consider an object object and a decorator decorator. ...
0
votes
1answer
137 views

Singleton: Why is a global point of access bad? [duplicate]

Most people here and on StackOverflow agree that Singletons are evil. The main explanation I've come across against the use of Singletons, is they fact that they provide a global point of access to ...
2
votes
2answers
131 views

Refactoring sought for replacing shared data types in .NET component

I am in charge with updating a software product that is made up of two components the Controller process and the UI process. The Controller and the UI communicate via XML messages. Furthermore, the ...
0
votes
1answer
144 views

MVC in a desktop application - can the View ever hold a reference to the Model?

(I'm specifying this is a desktop application so people wouldn't refer specifically to web implementations of MVC). The title says it all pretty much. In an MVC structure - can the View ever hold a ...
7
votes
2answers
314 views

Dependency Inversion Principle: Understanding how both low level components and high level components depend on abstractions

I'm learning about the Dependency Inversion Principle. It states that: High level modules should not depend upon low-level modules. Both should depend upon abstractions. For a while I tried to ...
5
votes
3answers
416 views

Dependency Inversion Principle vs “Program to an interface, not an implementation”

I'm trying to understand how the Dependency Inversion Principle differs from the "program to an interface, not an implementation" principle. I understand what "Program to an interface, not an ...
1
vote
2answers
114 views

Initialization of objects in a system using dependency injection

This is a follow up question to the following post: Injecting dependencies (DI) in c++ applications In a system that uses DI, someone, somewhere should be responsible to create the various objects ...
2
votes
2answers
179 views

Injecting dependencies (DI) in c++ applications

I am playing with dependency injection, but i am not sure I am doing it right. Especially, I am not sure what should be the correct way to build classes with injected dependencies. Say I have a class ...
1
vote
1answer
46 views

Removing dependencies on subclass-specific behavior

I have a Message class which can contain multiple types of payloads (or sometimes no payload), each derived from a common Payload class. However, this becomes problematic because the Message class ...
1
vote
2answers
223 views

Need advice on design in Ruby On Rails

For personal educational purposes I am making a site for a conference. One of the object that exist in a conference is a session, which has different states and in each state it has slightly different ...
2
votes
4answers
302 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 ...
4
votes
1answer
209 views

Which relationship is more natural?

Have a quick question on how to best structure something for my Java project: I'm a user. I can work at one or more places. At those workplaces, I have one or more roles. For each of these roles, I ...
2
votes
3answers
491 views

Empty virtual method on base class VS abstract methods

I couldn't find a question that was not too specific to some case, so I'll try to make this very generic. We need an extractor base class to a set of documents, for example. Each document has its ...
1
vote
5answers
633 views

How do I deal with global variables in existing legacy code (or, what's better, global hell or pattern hell)?

So... We have this fairly complex project (~10k LOC, but there's duplicated code so it's hard to tell) with hundreds of global variables. The project has more dependencies on other projects, and many ...
6
votes
3answers
390 views

Are “Stocks” a TDD/Unit testing anti pattern?

From Martin Fowler's Mocks Aren't Stubs he states that Stubs provide canned answers to calls made during the test while Mocks objects pre-programmed with expectations which form a specification of the ...
2
votes
2answers
213 views

Pattern for multiple datasources

I've already read this question on CodeReview. I was hoping for general advice. I'm writing a service which will go to numerous data sources. Each source requires getting copious amounts of data ...
0
votes
1answer
824 views

Is this proper OO design for C++?

I recently took a software processes course and this is my first time attempting OO design on my own. I am trying to follow OO design principles and C++ conventions. I attempted and gave up on MVC for ...
1
vote
3answers
163 views

Should I consider loosely-coupling for class methods as well? [duplicate]

I'm a fan of Dependency Injection, however I don't know how much both public and private methods inside a class should be loosely-coupled. Just to picture it better, when I have both projectId and ...
37
votes
9answers
4k views

Do we need Logging when doing TDD?

When doing the Red, Green & Refactor cycle we should always write the minimum code to pass the test. This is the way I have been taught about TDD and the way almost all books describe the process. ...