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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Object Communication Design

Multiple top-level systems that communicate with each other via messages(events/commands). The Main class of the program wraps around all the systems and has a message dispacher component wich ...
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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 ...
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Why does(/did) Bertrand Meyer think subclassing is the only way to extend a “closed” module?

In Meyer's Object-Oriented Software Construction (1988) he defines the open/closed principle as follows: A module will be said to be open if it is still available for extension. For example, it ...
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How do I store multiple views of data in memory?

I have a bunch of modules. I can break these modules into different categories that are complete and do not overlap. For example, three categories, with ids that can be expressed as Animal, Vegetable, ...
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Stuck on design when attempting to create an object store

I'm working on a small scale API project but as it will be used and maintained by people that are not Software Engineers to trade I am attempting to keep the design as separate and identifiable as ...
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629 views

Assembler vs Entity Translator and Entities vs DTO

I was hoping that someone could explain the exact difference between an Assembler and Entity Translator. Martin Fowler describes the Assembler as a sort of Mapper(?) which converts DTOs into Domain ...
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260 views

What is the best design principle to add behavior in future to your API? [closed]

I'm designing an API. And, this API will be used by client. Currently I've two behaviors in a class definition. To illustrate the scenario, sample implementation looks like the following- public ...
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58 views

Storing reference to a model obtained using DataMapper to be able to call save on it

When using the DataMapper pattern, which involves modeling classes containing business logic and knowing absolutely nothing about persistence, caching,... I usually want the models to represent real-...
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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 ...
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How to make a datatype for something that represents either itself or two other things

Background Here's the actual problem I'm working on: I want a way to represent cards in the card game Magic: The Gathering. Most cards in the game are normal-looking cards, but some of them are ...
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134 views

Prevent circular dependencies without introducing intermediary library

TL;DR Below I'm working on a game server (in Java, but that part is less important), and have decided to split up the server logic from the engine logic; in part because they're in two different ...
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How is encapsulation broken by getters/setters, even when using MVC model [duplicate]

I was thinking about encapsulation in Java and then I thought how getters/setters break encapsulation. After I went through this , I saw many recommendations like to avoid getters/setters on fields ...
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355 views

Inheritance when following the Repository Pattern in PHP

I am trying to build a PHP application using the Repository Pattern but I'm not sure how I should implement the save method. I have an abstract class called ItemRepository which have the following ...
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Should I create a class if my function is complex and has a lot of variables?

This question is somewhat language-agnostic, but not completely, since Object Oriented Programming (OOP) is different in, for example, Java, which doesn't have first-class functions, than it is in ...
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1answer
241 views

What approach in DataMapper Pattern is better for multiple or joined tables?

Normally, a Data Mapper maps data of one particular table. (Theoretically it should be communicating between Storage and a Domain Object, but its not possible in my case, so I am directly ...
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1answer
135 views

Design Patterns when Class Needs External Awareness

When I was first taught Object Oriented principles, it was drilled into me that when using objects in a "hasA" relationship (or any similar situations where a helper object encapsulates a discrete ...
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Computing and returning a sub-object where the sub-object is stored in the object

I have a complex object which routinely needs to compute a sub-object representing various aspects of the parent's state as a bundle. For example, imagine the object represents information about an ...
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Who is the Owner of Information? Memento vs. Originator

Imagine for a second that I'm implementing the Memento Pattern, using the following classes. Classes An Originator class that has public and private, properties and fields respectively A Memento ...
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Manipulating data for a single file

I'm looking for a best practice solution for creating an object whose responsibility it is to handle file storage for a single file. I want to be able to read data from the file, write to the file, ...
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597 views

Is there a design pattern for managing deep many-to-many relationships?

I'm having trouble defining this data pattern I've come across working on several applications. It consists of: An object type which is composed of many objects itself A second object type, where ...
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144 views

Should a new type be created though it only wraps a single field?

Say I have an interface Species that's defined as public interface Species { String getId(); String getDescription(); } The question is simply this: Should I create different classes to ...
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Should Objects with lots of fields be broken up? [duplicate]

When I have an Object that has lots of fields is it better to have them all as fields or try to find logical groupings as their own Objects and make those the fields? I guess it comes down to which ...
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1answer
286 views

How should one model an ExchangeService object (in ews-java-api) for sharing MS Exchange connections?

I am creating an application which uses ews-java-api to connect to an MS Exchange server. Once the connection is authenticated, the api dictates use of ExchangeService object for searching mailboxes, ...
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For DI, where to create dependencies (new objects) specifically within framework code?

Basic requirement I'm making a framework for learning purposes (and likely usage on personal sites). I'm using dependency injection in classes and I'm trying to design where would be a good place ...
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176 views

How to best model an application's settings?

My application has a configuration file and a "Settings" window. When the user confirms the changes in this window they are applied and written to the config file. These settings are often changed ...
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153 views

Private method with a derivable argument - a code smell?

We're implementing a service for creating a subscription where the subscription may be linked to an order. Quick background: the purpose of this service is to allow the customer to receive the item ...
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478 views

OOP Principles in Customer and Account classes of a Bank

I am designing a Bank Application which deals with Customers having FD Accounts. There are two approaches to this : Approach 1 In this the customer has a list of accounts. The bank application ...
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two repositories with kind of different behavior serving same object

I have a simple object like this public class Book { public List Chapters { get; private set; } public TableOfContent BookTOC { get; set; } public string Identifier { ...
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How to understand if a property is a member of a class or I have to create a different class that holds it?

Sometimes when you create a class you can add there several properties (new data members) that you are not certain if you want to do or not. For example, I have a casino slots game. I have tiles and ...
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321 views

'Encapsulation Vs Performance' trade-off in a lockable linked list

Main purpose of encapsulation is to protect in-variants of any class(in java). Here is the complete code for class DList/class lockDList/class DListNode/class LockDListNode. class DList and it's ...
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How should I structure these Python classes?

Base Class I have a class called Remote. This class represents a remote machine and has properties such as ip, hostname, username, and password, as well as methods for transferring files to/from the ...
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Design pattern for data structure that contains at most one item of each type

I have a superinterface that several different abstract classes implement: Coverage. This is for insurance rating. There are several types of different coverage, and those coverages might vary by ...
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3answers
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How to share data members between classes in C++ without violating encapsulation too much

In C++ let's say I have some class A: Class A { int a1, a2, a3; void foo(); } and I need to use a subset of members (a1, a2) in a member function for a second class B. ...
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Python classes with only one instance: When to create a (single) class instance and when to work with the class instead?

Given a Python class which will be instantiated only once, i.e. there will be only one object of the class. I was wondering in which cases it makes sense to create a single class instance instead of ...
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How to better define SRP and “wholesome” objects? [duplicate]

Assume you have a class. It can really be any class that defines a domain concept like an employee, a product on an e-commerce site, or a car. One of those examples that are oldies but goodies. ...
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EF “Code First” and Object/Relational Impedance

I'm trying to learn more about the current orthodoxy with respect to ASP.NET MVC application design, and I stumbled upon something that confuses me, relating to the choice among database design ...
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Is this a valid situation for returning rather than throwing an exception?

This is not something I would ever normally do, but I have a situation where some existing legacy code is being reused in a new application. The code is shared and needs to be used by both the legacy ...
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How to avoid god controller classes and keep single responsibility principle?

The task is to make a migrator from Old DB to New DB using OOP Single Responsibility Principle. My problem is how can I make this without making the controller a God Class or breaking the single ...
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Should I put the parameters in constructor or in method? (Python 3)

I have the following code: def __init__(self, vocable_file_path, xsd_file_path, word_list_file_path): self.vocable_file_path = vocable_file_path self.xsd_file_path = xsd_file_path self....
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How can I add properties to subclasses and access them without casting from a superclass?

I'm trying to model a multi-dimensional point class in C#. I have about eight different types of points, and there may be more in the future. Right now, I have a superclass (PointBase) that holds all ...
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How to reference one object with two interfaces? [duplicate]

Suppose I have two interfaces I and J that is implemented by Test class. Now I need one object of class Test that is referenced by I and J both interfaces. I can do it by singleton design pattern. But ...
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169 views

Inefficient use of interfaces in OOP (C#)

In my code, I've got two interfaces, let's say IOpenable and IExaminable. IOpenable allows the user to Open or Close the object, and IExaminable allows the user to Examine the object. Now, we have ...
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“Correct” way to use inheritance

Within a small project, a class Storage is meant to store any type of Item. Now, an Item has a String name, and an interaction. For example, a clock item might implement the interaction increment(int ...
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224 views

How to write procedural code in an object oriented language?

I recently started working in domain of mesh generation . My programs usually contains large chunks of procedural code consisting of several phases. Eg. class MeshAlgo1 { /* A very long function ...
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398 views

How to better isolate JOGL or LWJGL3 dependency from game clients?

I'm currently working on a project to develop a relatively small framework with the goal of supporting game development efforts for students in a course. The scope of this project is an OpenGL-based ...
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1answer
115 views

HashMap to replace Singletons?

Consider the following: I have controllers and views in a client-application. As this runs purely on the client side, each controller must only exist once. At first I thought about implementing ...
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COM - with great power comes great responsibility, but at what cost? (looking for advice on coding practices when working with COM)

What is best (or commonly accepted) practice for where to declare COM object variables (scope) and how to handle cleaning them up when using structured error handling? I just spend a whole load of ...
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Is it acceptable to define a “module” and “class” within a single .VB element?

Experiment: I have found it is possible to define both a "Module" (Namespace?) and a "Class" (Namespace?) within a single .Vb element (Module??). You can try this at home: Create a new Console ...
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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 ...
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What categories of software modeling problems is object orientation highly unsuitable for? [closed]

I'm trying to get a better grasp of the applicability of object-oriented programming and design. I'm curious about some examples of situations where object orientation is not simply inefficient or ...