Mnemonics for set of design principles: Single responsibility, Open-closed, Liskov substitution, Interface segregation, Dependency inversion

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Dealing with an often occuring dependency that is not related to the class

I'm using view classes for my templating. These view classes often require the Routing class to get URI's from other pages. You could actually say that the Routing should be available to every view ...
3
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2answers
728 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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2answers
367 views

Too many CS files in a single project [duplicate]

I am working on a ‘brown-field’ project, with a team of programmers. I understand each programmer will have different styles. I am running into some criticism with my coding style, specifically ...
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1answer
229 views

Is more dependency inversion always better?

Is there any situation in industrial object-oriented programming when the dependency inversion principle should not be used?
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1answer
178 views

Handling array passed to object at creation

When creating my object I pass it an array of a row from my database. (everything in the array we will need, disregarding unnecessary elements at sql query level) When I need to access certain array ...
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2answers
808 views

Interface Segregation Principle - type hinting multiple interfaces

The question is about typehinting of the role interfaces. The code example has two DataMappers which typehint the interface they need in the constructor, FooDataMapper type hints the Preparable ...
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2answers
253 views

Achieving multiple tasks within one loop

With relation to what's considered good OOP engineering principles, SOLID, DRY, KISS etc I am wondering whether to complete multiple tasks within one loop when easily done. The problem is that this ...
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2answers
305 views

Single responsibility vs procedural programming [duplicate]

Single responsibility (from SOLID) is like making me create classes with only one public method. But if it's so, it would be possible use static methods, and go back to procedural programming. What's ...
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8answers
3k views

What is the real responsibility of a class?

I keep wondering if it is legitimate to use verbs that are based on nouns in OOP. I came across this brilliant article, though I still disagree with the point it makes. To explain the problem a bit ...
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1answer
983 views

Liskov principle: violation by type-hinting

According to the Liskov principle, a construction like the one below is invalid, as it strengthens a pre-condition. I know the example is pointless/nonsense, but when I last asked a question like ...
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4answers
415 views

Is throwing an error in unpredictable subclass-specific circumstances a violation of LSP?

Let's say I wanted to create a Java List<String> (see spec) implementation that uses a complex subsystem, such as a database or file system, for its store so that it acts as a persistent ...
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4answers
300 views

Why should IQueryProvider implementations throw NotSupportedExceptions?

Searching the web, we can find plentiful examples of various ORMs (nHibernate, EF, LinqToSql, etc.) that implement but don't actually support the full IQueryable<T> interface, throwing ...
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3answers
1k views

SOLID Application Structure and Design

A one possible structure for an application is to have it broken down into modules such as Data Access, Core, Services, UI. Now depending on what type of ORM you are using Data Access layer will have ...
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1answer
128 views

The line between ByRef Parameters and Module Variables

This question was brought up during a Standards discussion, which should revolve around SOLID Principles for Object Oriented Development. In your experiences, have you seen benefits or drawbacks in ...
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3answers
283 views

How can I improve this design so that I don't need to dynamically scan classes at runtime?

I'm in the middle of a redesign on the part of my current project that deals with user permissions and authorization. I have an interface named IUserPermissions that encapsulates this information. ...
122
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6answers
15k views

SOLID Principles and code structure

At a recent job interview, I couldn't answer a question about SOLID -- beyond providing the basic meaning of the various principles. It really bugs me. I have done a couple of days worth of digging ...
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3answers
951 views

Two contradicting definitions of Interface Segregation Principle – which one is correct?

When reading articles on ISP, there seem to be two contradicting definitions of ISP: According to first definition ( see 1, 2, 3), ISP states that classes implementing the interface shouldn't be ...
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2answers
675 views

Is it a Single Responsibility Principle violation?

I'm designing an OO graph library and at the moment I'm trying to figure out the design for a GraphEdge class. I've added setters and getters for it's nodes, direction and weight. This seemes ...
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2answers
2k views

Programming against a protocol in Objective-C

I stumbled accross the SOLID principles. There is one burning question. Should I always use protocols? I never saw someone using them in the way that a Java developer would use them. I tried it in a ...
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1answer
249 views

Creating an interface of interfaces

Background: We have a class that both listens on a socket and sets values on itself based on what it reads off the socket. I believe that adheres to SRP. To adhere to ISP we created one interface ...
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2answers
542 views

Is it good to have an interface plenty of methods which belong to different concepts, just to preserve the Liskov's Principle?

I'm currently studying a course based on Software Design and I had a discussion in class with my professor and some classmates about a problem represented by the next scenario: Scenario Imagine ...
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2answers
350 views

Single Responsibility principle VS KISS principle

Let's assume the modeling of User model in a context of a social network. User concept is composed of two notions: Authentication elements like userName/Password/Email etc... Extra data information ...
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1answer
651 views

Xerox SOLID example in PHP

There is a good example on Wikipedia regarding the violation of SOLID principles. The ISP was first used and formulated by Robert C. Martin while consulting for Xerox. Xerox had created a new ...
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2answers
182 views

Are there any well-known quantitative approaches to evaluate a particular design whether it satisfies or violates the SOLID design principles? [duplicate]

I designed an application framework by considering the SOLID design principles and supported by design patterns. However, I wonder if there are any automated tools or well-known approaches to evaluate ...
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3answers
666 views

Do setters and getters always break the Single-Responsibility Principle?

As we know, The SRP states that every class should have single responsibility and that responsibility must be entirely encapsulated by the class. But setters and getters do serve another ...
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3answers
481 views

Simple questions to test understanding of Dependency Inversion Principle

I am preparing a short (1-2 hour) presentation about DIP to several (~5) junior developers (1-3 yr xp) in the office. At the end of the presentation I want to know whether they understood what I was ...
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3answers
931 views

Dependency Inversion Principle: How to define “high-level policy” and “low-level detail” to other people?

I am trying to explain the dependency inversion principle to my (mostly junior) colleagues. How can we define which one is the "high-level policy" and which one is the "low-level detail" in a ...
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1answer
434 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 ...
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3answers
261 views

Should methods always be closed for modification?

Say I have a method called 'functionA' that is called by a service and carries out a single piece of functionality, it is easy to unit test as it is does one thing only. If a few months later an new ...
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5answers
873 views

What is the meaning of “inversion” in Dependency Inversion design principle?

I'm reading about design patterns. I know what this principle does. High-level and low-level classes depend on abstractions. But why we say this is inversion?
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1answer
136 views

What are the reasons for rebuild and redeployment libraries?

It's difficult to understand the meaning of the question from the topic's name. Here is what I mean. I'm watching Uncle Bob's Clean Code Episodes. In many episodes where he is talking about SOLID ...
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6answers
542 views

Do changes in performance violate the Liskov Substitution Principle?

Say I have: interface Thing { GetThing(); } class FastThing : Thing { public int GetThing() { return 1; } } class SlowThing : Thing { public int GetThing() { ...
3
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2answers
336 views

Can I apply SOLID concepts to entire solution designs rather than just the internal components?

So maybe the quick answer is 'Yes' absolutely (or no I suppose), but let me explain my question angle to get a better derived answer. We all commonly use SOLID design principals when making up the ...
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2answers
659 views

Liskov substitution and abstract classes / strategy pattern

I'm trying to follow LSP in practical programming. And I wonder if different constructors of subclasses violate it. It would be great to hear an explanation instead of just yes/no. Thanks much! P.S. ...
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6answers
6k views

LSP vs OCP / Liskov Substitution VS Open Close

I am trying to understand the SOLID principles of OOP and I've come to the conclusion that LSP and OCP have some similarities (if not to say more). the open/closed principle states "software ...
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3answers
885 views

Tension between the dependency inversion principle and avoiding “new” in C++?

I have seen a lot of advice that it is better to do Type object; than Type* object = new Type(); in C++ whenever possible—i.e., minimize your use of new. I understand the rational behind this and ...
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2answers
321 views

Examples of Liskov Substitution [closed]

I'm facilitating a session next week on the Liskov Substitution Principle and I was wondering if anyone had any examples of violations 'from the trenches'? I'm looking for something other than uncle ...
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1answer
1k views

Is wrapping a third party code the only solution to unit test its consumers?

I'm doing unit testing and in one of my classes I need to send a mail from one of the methods, so using constructor injection I inject an instance of Zend_Mail class which is in Zend framework. Now ...
4
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4answers
375 views

Are injectable classes allowed to have constructor parameters in DI?

Given the following code: class ClientClass{ public function print(){ //some code to calculate $inputString $parser= new Parser($inputString); $result= ...
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9answers
3k views

What can go wrong if the Liskov substitution principle is violated?

I was following this highly voted question on possible violation of Liskov Substitution principle. I know what the Liskov Substitution principle is, but what is still not clear in my mind is what ...
13
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1answer
863 views

How to verify the Liskov substitution principle in an inheritance hierarchy?

Inspired by this answer: Liskov Substitution Principle requires that Preconditions cannot be strengthened in a subtype. Postconditions cannot be weakened in a subtype. Invariants ...
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8answers
7k views

Is this a violation of the Liskov Substitution Principle?

Say we have a list of Task entities, and a ProjectTask sub type. Tasks can be closed at any time, except ProjectTasks which cannot be closed once they have a status of Started. The UI should ensure ...
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2answers
2k views

Equivalent of SOLID principles for functional programming

I've found the SOLID principles quite useful when thinking about object-oriented design. Is there a similar / equivalent set of language-agnostic principles tailored for functional programming?
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5answers
522 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 ...
9
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2answers
494 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 ...
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5answers
655 views

Is my mediator layer a sensible way to manage this scenario using the Single Responsibility Principle?

I'm not sure how to start to explain my question, but here goes. We have just finished an MVC application that hits 2 WCF services. But there has been a bit of a disagreement between those who worked ...
31
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3answers
18k views

Programming SOLID Principles

Over time I could understand two parts of SOLID – the “S” and “O”. “O” – I learned Open Closed Principle with the help of Inheritance and Strategy Pattern. “S” – I learned Single Responsibility ...
24
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5answers
10k views

What are the design principles that promote testable code? (designing testable code vs driving design through tests)

Most of the projects that I work on consider development and unit testing in isolation which makes writing unit tests at a later instance a nightmare. My objective is to keep testing in mind during ...
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5answers
783 views

Is overloading an example of the Open/closed principle?

Wikipedia says "software entities (classes, modules, functions, etc.) should be open for extension, but closed for modification" The word functions caught my eyes, and I now wonder if we can ...
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4answers
3k views

Where should you put constants and why?

In our mostly large applications, we usually have a only few locations for constants: One class for GUI and internal contstants (Tab Page titles, Group Box titles, calculation factors, enumerations) ...