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A methodology that enables a system to be modeled as a set of objects that can be controlled and manipulated in a modular manner

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Often, in libraries especially, packages contains classes that are organized around a single concept. Examples: xml, sql, user, config, db. I think we all feel pretty naturally that these packages ...
Nicole's user avatar
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I understand what composition is in OOP, but I am not able to get a clear idea of what Aggregation is. Can someone explain?
Vinoth Kumar C M's user avatar
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I was told by a colleague that in Java object creation is the most expensive operation you could perform. So I can only conclude to create as few objects as possible. This seems somewhat to defeat ...
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Is the visibility private of class fields/properties/attributes useful? In OOP, sooner or later, you are going to make a subclass of a class and in that case, it is good to understand and be able to ...
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If immutable objects¹ are good, simple and offer benefits in concurrent programming why do programmers keep creating mutable objects²? I have four years of experience in Java programming and as I see ...
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6 revs, 5 users 38%
ahsteele
246 votes
15 answers
255k views

Why do we need private variables in classes? Every book on programming I've read says this is a private variable, this is how you define it but stops there. The wording of these explanations always ...
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Getters and setters are often criticized as being not proper OO. On the other hand, most OO code I've seen has extensive getters and setters. When are getters and setters justified? Do you try to ...
Community wiki
16 revs, 7 users 35%
Winston Ewert
169 votes
18 answers
305k views

I am looking for a recommendation here. I am struggling with whether it is better to return NULL or an empty value from a method when the return value is not present or cannot be determined. Take ...
P B's user avatar
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165 votes
7 answers
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I'm working with web development since 2009, when I started with PHP. When I moved to ASP.NET, I've heard a lot about DDD and OOAD where a lot of focus is given to this "business logic" and &...
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In the last few months, the mantra "favor composition over inheritance" seems to have sprung up out of nowhere and become almost some sort of meme within the programming community. And every time I ...
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Mason Wheeler
153 votes
14 answers
125k views

In object-oriented programming, there is of course no exact rule on the maximum length of a method , but I still found these two quotes somewhat contradicting each other, so I would like to hear what ...
Spring's user avatar
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I just started my first job as a software developer over a month ago. Everything I have learned about OOP, SOLID, DRY, YAGNI, design patterns, SRP, etc. can be thrown out the window. They use C# .NET ...
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Reportedly, Alan Kay is the inventor of the term "object oriented". And he is often quoted as having said that what we call OO today is not what he meant. For example, I just found this on ...
Charlie Flowers's user avatar
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It seems that C has its own quasi-objects such as 'structs' that can be considered as objects (in the high-level way that we would normally think). And also, C files themselves are basically separate ...
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I'm just now learning TDD. It's my understanding that private methods are untestable and shouldn't be worried about because the public API will provide enough information for verifying an object's ...
pup's user avatar
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114 votes
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I just wanted to clear up a question I have. What is the point of having a private static method as opposed to a normal method with private visibility? I would have thought an advantage to having a ...
Rehan Naqvi's user avatar
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106 votes
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The basic idea behind OOP is that data and behavior (upon that data) are inseparable and they are coupled by the idea of an object of a class. Object have data and methods that work with that (and ...
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Encapsulation tells me to make all or almost all fields private and expose these by getters/setters. But now libraries such as Lombok appear which allow us to expose all private fields by one short ...
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For example, to keep a CPU on in Android, I can use code like this: PowerManager powerManager = (PowerManager)getSystemService(POWER_SERVICE); WakeLock wakeLock = powerManager.newWakeLock(...
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So, we've got a guy who likes to write methods that take Objects as parameters, so they can be 'very flexible.' Then, internally, he either does direct casting, reflection or method overloading to ...
Community wiki
6 revs, 5 users 46%
Risser
101 votes
22 answers
59k views

When I started using an object-oriented language (Java), I pretty much just went "Cool" and started coding. I've never really thought about it until only recently after having read lots of questions ...
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gablin
99 votes
9 answers
20k views

I have been in two software product houses for three years in a row. The first is a small company maintaining a fairly small management system with a monolithic legacy code base (almost twenty years). ...
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Is it bad practice that a controller calls a repository instead of a service? To explain more: I figure out that in good design controllers call services and services use repositories. But sometimes ...
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98 votes
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I've heard a lot of talk about using functional languages such as Haskell as of late. What are some of the big differences, pros and cons of functional programming vs. object-oriented programming?
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In the debate of Rich vs. Anemic domain models, the internet is full of philosophical advice but short on authoritative examples. The objective of this question is to find definitive guidelines and ...
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96 votes
15 answers
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I code a lot in both C and C++, but did not expect C to be the second most popular language, slightly behind Java. TIOBE Programming Community Index I'm curious as to why, in this age of OOP, C is ...
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mmirzadeh
92 votes
10 answers
56k views

I'm having something of a hard time with designing classes in an oo way. I've read that objects expose their behavior, not their data; therefore, rather than using getter/setters to modify data, the ...
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One can often hear that OOP naturally corresponds to the way people think about the world. But I would strongly disagree with this statement: We (or at least I) conceptualize the world in terms of ...
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2 revs
zvrba
85 votes
14 answers
14k views

Does an object have to represent an entity? By an entity I mean something like a Product, Motor, a ParkingLot etc, a physical, or even a clear-cut non-physical conceptual object -- something that ...
Dennis's user avatar
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84 votes
6 answers
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Why do many software developers violate the open/closed principle by modifying many things like renaming functions which will break the application after upgrading? This question jumps to my head ...
Anyname Donotcare's user avatar
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I’m still really new to learning to program. Just learning the syntax for a few programming languages at the moment. The courses I viewed for C# and Java touched only very briefly on getters & ...
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I'm trying to understand the difference between procedural languages like C and object-oriented languages like C++. I've never used C++, but I've been discussing with my friends on how to ...
niko's user avatar
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80 votes
11 answers
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Stroustrup says "Don’t immediately invent a unique base for all of your classes (an Object class). Typically, you can do better without it for many/most classes." (The C++ Programming Language Fourth ...
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Downcasting means casting from a base class (or interface) to a subclass or leaf class. An example of a downcast might be if you cast from System.Object to some other type. Downcasting is unpopular, ...
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How does a functional programming language, such as Elm, achieve "No runtime exceptions"? Coming from an OOP background, runtime exceptions have been part of whatever framework that is based ...
Fireburn's user avatar
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Javascript is a prototype-based object oriented language but can become class-based in a variety of ways, either by: Writing the functions to be used as classes by yourself Use a nifty class system in ...
Spoike's user avatar
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The Single Responsibility Principle states that a class should do one and only one thing. Some cases are pretty clear cut. Others, though, are difficult because what looks like "one thing" when ...
dsimcha's user avatar
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What's the difference between the two UpdateSubject methods below? I felt using static methods is better if you just want to operate on the entities. In which situations should I go with non-static ...
Alexander's user avatar
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74 votes
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I have read that in OOP, we think of objects as "sending messages to each other", for example if we did car1.stop(), we say that "we sent the message stop() to the car1 object". ...
Christopher's user avatar
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71 votes
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In some code I'm reviewing, I'm seeing stuff that's the moral equivalent of the following: public class Foo { private Bar bar; public MethodA() { bar = new Bar(); bar.A();...
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71 votes
8 answers
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Coming from a math background, counterexamples are equally, if not more, helpful to me for understanding concepts than examples. I've seen many, many examples of when and how to use the SOLID ...
Derek Allums's user avatar
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67 votes
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The main idea behind OOP is to unify data and behavior in a single entity - the object. In procedural programming there is data and separately algorithms modifying the data. In the Model-View-...
Random42's user avatar
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66 votes
11 answers
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After studying Programming through books, they have taught me concepts such as inheritance, but never explain how splitting a program into multiple classes helps with anything. Yet, many books seem to ...
kullalok's user avatar
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66 votes
1 answer
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C++ has plain multiple inheritance, many language designs forbid it as dangerous. But some languages like Ruby and PHP use strange syntax to do the same thing and call it mixins or traits. I heard ...
Gherman's user avatar
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8 answers
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I had a very stimulating and interessting discussion with a colleague about ORM and its pros and cons. In my opinion, an ORM is useful only in the rarest cases. At least in my experience. But I don't ...
derphil's user avatar
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Today I had an argument with someone. I was explaining the benefits of having a rich domain model as opposed to an anemic domain model. And I demoed my point with a simple class looking like that: ...
tobiak777's user avatar
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65 votes
10 answers
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Which is generally accepted practice between these two cases: function insertIntoDatabase(Account account, Otherthing thing) { database.insertMethod(account.getId(), thing.getId(), thing....
AJJ's user avatar
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63 votes
8 answers
29k views

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 ...
Kolyunya's user avatar
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59 votes
9 answers
23k views

This blogpost was posted on Hacker News with several upvotes. Coming from C++, most of these examples seem to go against what I've been taught. Such as example #2: Bad: def check_for_overheating(...
Pubby's user avatar
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Where I work I see lots of classes that do things like this: public class ClassThatCallsItsOwnGettersAndSetters { private String field; public String getField() { return field; }...
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