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

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Dependency Inversion Principle - No deriving from concrete classes?

I'm not sure if I am getting this right. In order to observe proper SOLID principles, am I forbidden to inherit from concrete classes? Does that mean that every concrete class that I have more or less ...
0
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1answer
81 views

Are new empty Java marker interfaces created to satisfy an existing method contract a code smell?

Suppose I have a POJO A and some client code that serves it. I have created POJO B, which doesn't have anything in common with A, but I want to use it in the methods that use A, so I decided to create ...
4
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4answers
959 views

Is this 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 ...
13
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4answers
1k views

How specific should the Single Responsibility pattern be for classes?

For example, suppose you have a console game program, which has all kinds of input/output methods to and from the console. Would it be smart to keep them all in a single inputOutput class or break ...
2
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2answers
110 views

Method to validate an object - should I have one method encapsulating all validation logic

I have a class, Customer which has some basic properties on it such as firstname, surname, email, dateofbirth. I have written another class called CustomerValidation which currently has one public ...
2
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1answer
80 views

How do you keep up with 'requiring new methods in an interface' (Following LSP and adding new methods to interface seems to violate ISP)

I have a game that deals with opening and closing doors and the Door Engine deals with IDoor interface which has Open() and Close() contracts So far so good. the game is tested and works fine. Now a ...
4
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3answers
282 views

Does the visitor pattern violate the Liskov Substitution Principle

When using the Visitor pattern, I have observed the following: The visitor has weak dependencies to concrete types (each visit method has the concrete element as a parameter or is a method that ...
5
votes
7answers
429 views

Does calling a virtual protected method from a base class violate the LSP?

Let's say we have this base class: class MyBase { public string Name { get; set; } public string GetDescription() { var descriptionList = new List<string>() { this.Name }; ...
4
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1answer
299 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 ...
3
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2answers
500 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, ...
7
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4answers
571 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 ...
2
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1answer
1k 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
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When in your language classes are objects too, does the Liskov substitution principle apply to their interfaces?

According to Wikipedia the Liskov substitution principle states that objects in a program should be replaceable with instances of their subtypes without altering the correctness of that program ...
13
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1answer
1k 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 ...
6
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2answers
713 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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1answer
119 views

Code structure of third party framework [closed]

Is an API always returning 200 OK, an issue?
0
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0answers
94 views

Making code more “modular”

As an semi-experienced procedural PHP developer, my OOP still needs a lot of work. I am still working through SOLID principles and other theories and guidelines of OOP, and am stuck with something ...
20
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4answers
2k views

Do special-cases with fallbacks violate the Liskov Substitution Principle?

Let's say I have an interface FooInterface that has the following signature: interface FooInterface { public function doSomething(SomethingInterface something); } And a concrete class ...
85
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8answers
9k 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 ...
22
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9answers
4k 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 ...
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6answers
8k 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 ...
0
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2answers
230 views

Without using Singletons, what is a good way to manage a global resource? [duplicate]

Unlike many libraries SDL and OpenGL are designed to provide global resources; you can access them at any time from any class. There are justifications for this: They are written in C, meant to be ...
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3answers
189 views

Can the circle-ellipse problem be solved by reversing the relationship?

Having Circle extend Ellipse breaks the Liskov Substition Principle, because it modifies a postcondition: namely, you can set X and Y independently to draw an ellipse, but X must always equal Y for ...
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3answers
103 views

SOLID principles and generating many objects from a file

The "D" in SOLID stands for dependency inversion. If I have for example, a Blacksmith class that depends on Hammer, I should create my Hammer externally and pass it to Blacksmith, rather than having ...
2
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2answers
415 views

What did the reviewer refer to in this code review?

I sent the code for a job application and got the following review: Regarding the Project Structure: Physical separation is absent. Logical separation is present but not up to best practices. Things ...
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1answer
56 views

Should Laravel's App::make() be considered a dependency?

I think the question in general is best summed up as, should Laravel's App::make() be considered a dependency? On the one hand it can instantiate any number of different implementations, so maybe it ...
2
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2answers
51 views

Is it a bad practice to return third party reference from public method?

Let's consider an example from WebDriver where I create two different classes to deal with page object, one stores the element locator and other actual operations dealing with page - public class ...
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1answer
85 views

Does my example violate LSP?

Consider this example: public class SimpleValidator { public virtual bool InRange(int x) { return x >= 6 && x <=12; } } public class OffsetAwareValidator : ...
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1answer
191 views

Is defining only one method against S in S.O.L.I.D

The first version of pseudo code I consider a code smell because of (I think) the Command Query Separation principle and/or the S in S.O.L.I.D. What I like to see is in the 2nd version. Should I keep ...
3
votes
3answers
176 views

Would dependency injecting into entites be considered against SRP?

I asking a question on Stackoverflow earlier and someone pointed me to a previous post of his, He states that injecting a dependency into an entity violates the Single Responsibility Principle. To ...
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2answers
853 views

How to use SOLID principles in this example

I have reading about SOLID principles last week and decided to try to solve real world problem by using them. So I got the problem of real world ecommerce site managing totals. Problem Statement: ...
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1answer
237 views

Open / Closed Principle

I found this code example explaining Open / Closed principle. Code before application of principle: public class Logger { public void Log(string message, LogType logType) { switch ...
2
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4answers
861 views

Gathering IP address and workstation information; does it belong in a state class?

I'm writing an enterprisey utility that collects exception information and writes to the Windows Event Log, sends an email, etc. This utility class will be used by all applications in the corporation: ...
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vote
1answer
42 views

Does having a EntityBase or DomainBase class violate LSP?

Suppose we have a abstract class EntityBase which is the base class for all our entities e.g. public abstract class EntityBase { public Guid Id {get;set;} } public class Customer : EntityBase { ...
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2answers
835 views

How do you apply Single Responsibility principle to a repository

I am trying to apply "SOLID" whenever I can and try to use common sense and avoid a pattern when I see that a pattern is creating more problems than it's trying to solve. I don't want to apply a ...
9
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2answers
471 views

Interface Segregation Principle: What to do if interfaces have significant overlap?

From Agile Software Development, Principles, Patterns, and Practices: Pearson New International Edition: Sometimes, the methods invoked by different groups of clients will overlap. If the overlap ...
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votes
1answer
46 views

SRP. Save to repository when edit. Internally or externally? [closed]

For example: class Data { private String field1; private String field2; public void someEditMethod() {} } class DataRepository { public void save(Data data) { // save to DB ...
3
votes
2answers
210 views

Is Dependency Inversion a valid alternative to the pImpl idiom?

If I want to present to the user of my code an interface, that is unlikely to change, I can write only the public part of the classes in public headers and have a single private pointer to another ...
3
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5answers
133 views

Can encapsulation be implemented by proper types rather than accessors?

Interesting question came up while designing interfaces at work, now resolved, but I want to ask about the theory behind it. Is it incorrect to say that properly typed data members of a class provide ...
5
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1answer
97 views

Choosing between Dependency Inversion and Dependency “Delegation” to a third module

Suppose I have MasterPackage containing a Master class, and BlasterPackage containing Blaster class. Since Master needs a Blaster to work, the higher level MasterPackage depends directly on ...
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2answers
205 views

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 ...
2
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3answers
305 views

Is this avoiding inheritance correctly?

I want to add capabilities for an abstract Model class to send events whenever it updates. To be able to send events, it needs to have access to an EventManager. So, the intent were first, to be able ...
31
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7answers
4k views

When NOT to apply Dependency Inversion?

I am currently trying to figure out SOLID. So Dependency inversion means that any two classes should communicate via interfaces, not directly. E.g. if class A has a method, that expects a pointer to ...
3
votes
2answers
140 views

Design review of a small configuration framework [closed]

I want to create a simple configuration framework. Yes I know, there are many frameworks, which make their job very well. But for interesting in architecture, I want to create my own. My framework ...
26
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3answers
3k views

How is dependency inversion related to higher-order functions?

Today I've just seen this article which described the relevance of SOLID principle in F# development- F# and Design principles – SOLID And while addressing the last one - "Dependency inversion ...
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11answers
5k views

Ensure that each class has only one responsibility, why?

According to Microsoft documentation, the Wikipedia SOLID principe article, or most IT architects we must ensure that each class has only one responsibility. I would like to know why, because if ...
5
votes
1answer
185 views

What evidence is there that obeying the Open/Closed principle reduces bugs?

I'm currently putting together a talk where I discuss the value of unit tests in enforcing the SOLID Open/Closed principle. However beyond the obvious "the bug wasn't there when I wrote it, it's been ...
0
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1answer
73 views

Does extending a ruby class violate the LSP?

I am reading about SOLID principles. In Ruby tutorials and code samples, I often see subclass extensions like: class House attr_reader :items end class Room < House attr_reader :chair end p ...
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votes
2answers
225 views

Maintaing drop down lists for the application

What would be the best approach to maintain the dropdown lists for the whole application (like city, state etc) taking into account the SOLID principles and performance? Right now am loading the list ...
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0answers
71 views

Did Apple violate OCP back when they released iOS 7

If I remember correctly, back when iOS 7 was released, there were a couple of issues regarding the public API of certain classes which implementation was completely changed. The following is an ...