Object-oriented design is the process of planning a system of interacting objects for the purpose of solving a software problem.

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Query on hiding implementation details in java

With the below piece of thread related code, I see that author of Thread class is hiding the details about the working of start() method. What a user of Thread class need to know is, class Thread ...
4
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2answers
292 views

What are the valid uses of static classes?

I noticed that nearly every time I see programmers using static classes in object oriented languages such as C#, they are doing it wrong. The major problems are obviously the global state and the ...
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0answers
44 views

which language is best to learn [closed]

i know c,c++,html&css and basic java-script , i want to know that for which next language i should go for? i am totally confuse in ruby,java,php,asp,python,.net which should i start learning?? I ...
3
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3answers
163 views

Is it misleading to label code as a particular design pattern if it only loosely fits the definition?

Background: I have a rough, but working understanding of ~15 design patterns. It's been my experience using design patterns in my own projects that the resulting implementations usually end up as some ...
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2answers
91 views

Interface inherits from interface without specifying new member

Is it some kind of bad design to have something like this: public interface IFooStream { long Length { get; } long Position {get; set;} //... } public interface ...
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0answers
29 views

Where to place loops that are output data MVC [closed]

In ideal world view should only display html and echo php variables. Sometimes you would be required to do extra changes to the data while in the loop i.e reformat date or fetch extra information ...
2
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1answer
209 views

C# OOP Class Usage [duplicate]

I am just being picky and really wanted some of my code to look, feel, and be used a specific way but am not sure if its possible. I have a class I created that can be used like this ...
2
votes
3answers
172 views

Getters and Setters unclear example

I know autmatic getters and setters are considers bad as they tend to break object's encapsulation. They also move the work that should have been done within the object outside. Allen Holub is a big ...
3
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3answers
188 views

Best OOP Practice in C#: Passing the object as parameter VS creating a new instance of the object

First things first, I would like to know if passing an object as parameter is much better than creating another object AGAIN in a class that will use it again and second what are the pros and cons of ...
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0answers
53 views

Extend, wrap, or both to add generics to a class that should have had them?

So I'm using a C# framework that has a great example of where generics would be useful, except they weren't used. For simplicity's sake, we will say it was a list (I know C# has its own list), but ...
2
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0answers
62 views

Sharing constructor code between classes that do not inherit from each other

There is a PHP library of classes (generated from a WSDL) that cannot be changed. These look like the below for simplicity. class System extends \SoapClient { public function __construct(array ...
0
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1answer
79 views

Should Form Object be considered a DTO?

I got this from one of online video tutorials. Author binds form data not to Value Object directly, but first to validable DTO, and THEN to Value Object, using service. Example: package ...
5
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5answers
200 views

Specific empty children classes

Is having empty children classes, just to specify, a bad practice? Lets suppose I've a generic Product class. There are electrical, electronic and mechanical products. I need to represent all them ...
1
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1answer
53 views

Do the implementations of the Node interface in Web API violate Liskov Substitution Principle?

MDN article on Node interface states that interfaces [that inherit from Node interface] may return null in particular cases where the methods and properties are not relevant. They may throw an ...
0
votes
1answer
70 views

What are the key areas to evaluate software (codebase) on? [closed]

I have been asked to do a code review of about 50 applications over a period of 6 weeks. (Management has changed and the new CTO asked for an full internal software audit) I am wondering, what are ...
3
votes
3answers
485 views

Should an object load itself?

although I'm programming in C++ for some time now, I'm always faced with design decisions (probably due to the language's flexibility). One such problem is deciding if a method should be part of the ...
1
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0answers
82 views

Too many parameters to data processing class constructor

I have a conceptually simple application: data comes in as small encrypted packets, they decrypted and validated, some are stored in the database, some rules are applied, and a reply might be ...
1
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0answers
58 views

Need to refactor file downloader and post processing utility [duplicate]

Not sure whether this is the right forum to ask this but here goes. Using this solution - http://stackoverflow.com/questions/26571351/replacing-if-else-logic-with-state-strategy-pattern I was able to ...
1
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4answers
713 views

try/catch open/closed principle violation

I have three or more different custom exceptions that a class can throw and I need to use try/catch in order to discover which exception was thrown. In my point of view this piece of code violates ...
0
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0answers
49 views

OO Design Question - Library/Objects for API which includes id references

Public api: getClients / getClientById - returns a json object like: { clientid: 1, name: "Client1" } getProjects / getProjectById - returns a json object like { projectid: 5, name: ...
0
votes
4answers
636 views

Why 'List<E>' is an 'interface' but not 'abstract class'?

While defining the hierarchy, one can think to embed the abstract method(behaviour) in abstract class only because the derive concrete class posses that as core behaviour with it's specific ...
1
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0answers
108 views

Program Architecture: How to manage objects that are interdependent

Consider the following case, image I making a simple chat program; I want it to be extensible such that it would be fair easy to add add different scripting and user interfaces. I want the core ...
0
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3answers
117 views

OOP: relying on protected properties in a class-subclass contract

I'm coding in Python, but the question seems independent of programming language. I have a class that represents some system check: class Check: @abstractmethod def run() """ You have to ...
7
votes
2answers
204 views

Autoreleasing objects in Reference Counting Systems

I'm experimenting a bit in C and I'm trying to implement my own Reference Counting System. I've mainly worked with Objective-C in the past but AFAIK autoreleasing objects is something that is unique ...
2
votes
1answer
92 views

DDD: Global unique identities vs surrogate

Let's start with an example: we have an entity: Book. It has unique identity: Isbn - a value object that wraps a String. This is an UUID. The Book entity also needs a surrogate id from the repo (sql ...
1
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1answer
47 views

DDD: storing additional data with the model

Our domain is operated within certain context. This context is described by some additional values, like a fooId - id that does not have a meaning in domain business, but it's more a flavor for the ...
0
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1answer
70 views

DDD: Alternative view of the Model?

I have a model class, let's say it's a Book. I need it to be displayed on the screen. I want to have an escaped version of it, so I do not need to escape fields manually. What should I do? I can ...
2
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4answers
214 views

Determining a class structure

I'm currently in the early stages of designing an e-commerce application. I'm working out some designs for my classes which have so far been fairly straightforward, but I've run into something of a ...
3
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2answers
162 views

Model object and additional attributes

I have a model e.g. Book. Besides 'natural' attributes of a book, I have some mandatory IDs I need to carry on, like companyId, groupId. They are related to which organization unit this book belongs ...
3
votes
1answer
210 views

How to store a potentially large amount of optional properties of objects?

I'm using Entity Framework Code First with ASP.NET MVC. This handles my database design based on the domain models within my application. As it stands, the engine I'm writing will have a website ...
0
votes
2answers
134 views

Should I have an object as attribute or primitive id? [duplicate]

I am wondering which principle should I use. Here is my situation. I have a class named TravelOffer. This class looks like this: public class TravelOffer { private final long id; private ...
0
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1answer
137 views

What should be in a PIMPL?

I am kinda trying to implement a windowing library in C++, the circumstances are forcing me to implement it all myself, that's not the point of this question however. My question is: What should be ...
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votes
2answers
157 views

Why is inheritance generally viewed as a bad thing by OOP proponents [duplicate]

I keep hearing the phrase "Favour Composition over Inheritance" from GoF which is being annoyingly mentioned repeatedly by my friend who thinks it is a valid blanket statement but is it not more ...
0
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1answer
228 views

Separating UI from logic

I'm trying to develop a little game and for this I'd like to separate the UI from the game logic. So I'm thinking of using an "Animator" class that will be responsible for rendering the objects, but ...
3
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0answers
138 views

Lightweight data modeling vs traditional classes [closed]

I've heard a lot of talk about using lightweight data modeling as of late. Especially in relation to the Clojure programming language. What is it and how it differs from traditional classes regarding ...
2
votes
1answer
75 views

Design Question - System Integration

Guidance on good application architecture / design is not in short supply however most of the examples focus on some business object, like Customer and its behaviour and persistence. There is little ...
1
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1answer
221 views

Designing classes the right way [closed]

I am trying to design my classes in the optimal way for the following scenario. A city has metro lines covering a number of stations.There are 4 lines represented by 4 colors.The user has to enter ...
2
votes
1answer
82 views

Is there a limitation when using the Bloch's Builder Pattern with mandatory fields?

Background I have a class TextDrawable which draws text on top of a shape. There are a number of properties that can be set while creating a TextDrawable object. Mandatory Properties: Text Shape ...
14
votes
2answers
2k views

Illegal in PHP: Is there an OOP design reason?

The below interface inheritance is illegal in PHP, but I think it would be fairly useful in real life. Is there an actual antipattern or documented problem with the below design, that PHP is ...
8
votes
3answers
680 views

Clean Code and Hybrid Objects and Feature Envy

So I recently made some major refactorings to my code. One of the main things I tried to do was split out my classes into data objects and worker objects. This was inspired, among other things, by ...
1
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2answers
135 views

Deriving from a class only to provide a special constructor

In our codebase, I encountered the following construct: There is a base class B, and then there is a class D which derives from B, but does not override or add any members. In fact, D is completely ...
0
votes
1answer
163 views

Logic based on modified fields of a Hibernate entity

I have a Hibernate entity object MyObject with several attributes and a service MyObjectService containing business logic dealing with MyObject. I also have a view model dealing with user input/output ...
28
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8answers
6k views

When writing object-oriented code, should I always be following a design pattern?

Is there a conceivable design pattern for any object-oriented program? I ask this because recently I saw an implementation of a Door class with a Lock. It was part of a test and the answer said that ...
1
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2answers
63 views

Class template specialization for implementing Automata

I'm implementing classes for simulating and generating different kind of automata. I'd prefer to use the same State and Transition classes for all the automata: NFA, DFA, PDA, etc. For a PDA a ...
-2
votes
1answer
204 views

Base Class, with method that returns Derived Class. design flaw?

I'm writing a Math equation solver in python (for fun). The first design that came to my mind: Expression: base class for every item in an equation (maybe bad name). BinaryExpression extends ...
1
vote
2answers
256 views

When should I refactor a private class into a package-private class?

When I began implementing a class in my system (let's call it A), I realized I needed some kind of object that does something. So I needed a new class (let's call it B), but I made it a private static ...
2
votes
4answers
491 views

When should something be a class? And are my chosen classes good OO design?

My background: I am new to programming. Python is my only programming knowledge. I program as a hobby, and I'm teaching myself by reading copious amounts of books. I understand enough about OOP to ...
1
vote
1answer
102 views

Ignoring the generic part of a type while an object is being passed

I have a message class that holds the name of a destination, and a generic variable acting as the message payload public class Message<T> { public string Destination public T Payload ...
2
votes
1answer
92 views

Should this interpretation happen in the Controller or the Model?

Imagine an application where the user is allowed to create his/her own musical scales. The user selects notes from a list, arranges them to a group and presses a button to create the scale. In an MVC ...
0
votes
1answer
121 views

Design pattern for modifying state and notifying the other modifiers without a loop

The idea is that I have a set of properties that represent possible options in the app. These options can be modified through a variety of different ways, such as from the UI, remotely, third party, ...