A design pattern is a general reusable solution to a commonly occurring problem in software design.

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How to uncouple and reuse persistence logic, user interface logic and business logic amongs embedded software projects

I have been working in embedded devices business more than 5 years as a software engineer. Most of the times our hardware manufacturers provide a Software Development Kit for their reference boards. ...
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115 views

Fault tolerant software design of application running as distributed cluster

Mission-critical software system (such as systems-control software in spacecrafts) often employ multiple redundant software modules developed by different teams (sometimes using different programming ...
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109 views

File-Directory Implementation: Does a a file have to own a reference to it's dir?

I am currently issuing a problem while forming the program-design, which is exact like a File-Directory relationship, and to ease it, I am using that as an example. I think it is usual, that a ...
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Calculating a score and a breakdown of the score in different places - should I use the same methods?

I am creating a plugin that uses a metric to determine a score on one page and allows the user to click through to see a more detailed breakdown of the score on a separate page. The trouble is: I can'...
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Design for an Android app (pharmacy duties)

I am creating an android app for pharmacy duties for different cities. My approach: I created an Interface with method getDuties, and for every cities I create a class named with name of the city ...
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How is Inversion of Control related to Dependency Inversion

In many articles all over the web the terms Inversion of Control and Dependency Inversion Principle seem to be mixed up and used as synonyms (further confusion is enforced by the tools that are called ...
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Extending the flyweight pattern: an oxymoron?

I'm developing a BNF parser in PHP, for my own flavor of BNF. To keep the resulting parse tree, consisting of objects, as lightweight as possible, I decided to use the flyweight pattern for literals (...
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295 views

Strategy Pattern not sufficient for my problem?

Let me sketch the situation: I have multiple users, with certain properties (2 enums) For each user I need to fetch data, for some with some basic filtering, for some extended filtering (= basic ...
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240 views

Migrating large silverlight business application to MVC

I have the task to migrate a large silverlight business application in a new living technology. I had choosed asp.net MVC and web api. As we know, silverlight uses MVVM design pattern whereas asp.net ...
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OOP - Modeling a Chat Design Review [closed]

Seeking thoughts on the following design. I know the design could be lot simpler if use Sockets. But I wanted to think of a design with pure POJO classes. User string id; string displayname; ...
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263 views

Constructor with tons of parameters vs builder pattern

It is well know that if your class have a constructor with many parameters, say more than 4, then it is most probably a code smell. You need to reconsider if the class satisfies SRP. But what if we ...
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OO design: separation of concerns

I have a collection of classes which model Logical(Boolean) Expressions. There is a base abstract class LogicalExpression, and derived classes : UnaryLogicalExpression, BinaryLogicalExpression, ...
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Does a mutually exclusive Decorator design pattern exist?

We know the Decorator design pattern, but how would someone go about implementing mutually exclusive decorators? Let's say I have a decorator pattern to implement weapon modifiers in a game. The ...
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140 views

What is an appropriate pattern for handling a queue of network events in C++?

I'm writing an application that sends and receives messages over the network and pushes them into a std::deque queue. and I'm looking for the appropriate programming pattern to handle all of the ...
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1answer
82 views

Design patterns to limit cross module logic

I have a web application which has a shopping cart with cart items. The cart items are added to the user session, so must be serializable. I have a checkout class which takes the cart items and saves ...
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128 views

Abstraction on Iterator Pattern?

Recently, I had the task to implement a research project where I had to read an XML file. XML file contained a list of messages that I had to send to some other system on a specific port. Each message ...
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Layer application and token authentication

Suppose we have an application with multiple layers in .Net: Domain layer (entities) Data access layer (entity framework) Business layer Web Services layer (Web Api) Presentation layer (MVC) Now I ...
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A “sort of” Units of Unit of Work

I've read Unit of Work pattern and tons of MVC/EF Unit of Work examples but what I'm trying to do is encapsulate multiple unit-of-work into a large set. Maybe this pattern already exists somewhere, ...
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175 views

Suggestions to distributed service pattern

We expose some webservices on a server, written in C#. Now we have to distribute the services to multiple servers, so the solution is distributed. And each request is dispatched to one the servers to ...
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Data Mapper pattern vs. model encapsulation

I am currently developing my first custom data mapper layer but have run into a conceptual problem that seems to be glossed over all books and guides I have read. My problem is as follows. My data ...
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How do you handle sequentiallity in API's?

Consider a use case of the form: The system shows a list of potential filters (by name, by creation time...). User chooses a filter and supplies necessary parameters. System shows a list of ...
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Multiple inheritance in ASP.NET MVC Controller

In one case BaseWizardController should implement background functionality of BaseController->BaseConsumerController, in other case it should implement only BaseController. Any ideas how can I do ...
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174 views

Good design pattern to enable/disable certain functionality based on condition

I am working on a paint type application in android. I got toolbar on left contains tools like undoCut, redoCut, box, frame, cutting, coloring, next, previous etc. I wanted to know what is the best ...
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is Command appropriate software pattern for this?

I have following task: I need to send several instructions after each other to the hardware. Next instruction is never sent before either answer to previous instruction comes (valid answer or error) ...
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1answer
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How to make it clear I'm violating Command Query Separation

Command Query Separation is a useful principle, though it's not always ideal. Sometimes you need to run a process, which will result in useful data you need to return. My specific case is uploading a ...
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Proper way/place to apply decorator pattern for view layer in mvc

I have an array of model objects containing data some of which is states represented by integers. In the view these states are shown as icons and tooltips. The tooltip is needed only in the view and ...
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70 views

Architecture of approval process

I want to design an approval process for my work flow but I wonder if there is an architecrural pattern or desing pattern for this solution. For example an engineer will create a work. And program ...
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245 views

Generating Java Classes with Compile-time Value Parameters

Consider a situation where a class implements the same basic behavior, methods, et cetera, but multiple different versions of that class could exist for different uses. In my particular case, I have a ...
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Snap to grid functionality in drawing application

I'm working on drawing application and I want to provide grid with snap to grid functionality. I'm trying to find the right way how to do that (ideally some design pattern), but I'm quite confused ...
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How should an entity that abstracts an external service do its operations?

I'm creating a system using some DDD principles and I'm stuck with a problem. To give a bit more of context on what I'm trying to do, let me first describe what the system is about: The ideia is to ...
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Unifying database interface for multiple authentication methods

I'm working on a project with Mongo as the db. Currently, we only allow users to sign up with email and we look them up in the db by email address. But now we're moving to allow users to sign up ...
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How do you hash 4 doubles into a size_t?

I have bounding boxes the key type. Box { double mins[2]; double maxs[2]; } And I want to have Box as the key type in the D programming language, so I have to implement: size_t toHash() const @...
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1answer
174 views

Function pointers vs. Derived classes

So I have a Signal class and a client class which manages a list of Signal objects. The class provides a bunch of interfaces, one of them is an update()-function. The update()-code is completely ...
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166 views

Repositories, Gateways, Models and Architecture Questions

I am working with a Laravel project and I am looking for a way to solve the issue of bloated models and cross referencing between them. I had started extracting higher level methods to a repository ...
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Is there a design pattern to handle construction of complex objects with a [1 → 1..*] multiplicity relationship?

I have two classes (A and B) that are both complex to construct, with multiple properties that must be validated at construction time. I want to use the Builder pattern to construct these objects, but ...
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Respectable design pattern for making node modules flexible/testable?

I am looking to get some input from some more experienced testers than what I am. :) I am trying to make my node modules testable, allowing for dependency spying/stubbing/mocking without the need to ...
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Is Module Pattern in JavaScript is useful only for singleton creation?

Some articles (JavaScript Module Pattern In Depth, Mastering The Module Pattern) describe defining modules in JavaScript like in the snippet below (from Addy Osmani's "Learning JavaScript Design ...
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Pattern to use (if any) to co-ordinate loosely coupled classes with strong interdependencies

I have a collection of cooperative classes whose behaviors are interdependent upon one another. But I wish to keep them loosely coupled, so I've created appropriate interfaces. I want to determine an ...
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Is this an appropriate code structure, or is there a better one?

This is an iOS app but I will try to make it as general as possible because I think a wide audience could have good feedback. I have a application I am making for iOS. It has 4 main tabs in a tab bar ...
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Is turning a method into a class to use it across many classes bad practice? [closed]

Let's say I have a sort method inside of my class and another class that has no relationship with that class needs the same method. Instead of writing that method twice and breaking the do not repeat ...
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Why is chaining setters unconventional?

Having chaining implemented on beans is very handy: no need for overloading constructors, mega constructors, factories, and gives you increased readability. I can't think of any downsides, unless you ...
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Does such a design pattern exist? (Multi-Strategy/Multi-Traits)

Is there a design pattern that would allow a class from a hierarchy to 'subscribe to' concrete methods? For example, say you have an abstract base class that requires the implementation of a method. ...
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Compiler design prevent register override

I'm trying to write a compiler for a self-designed CPU with accompanying instruction set. The CPU has 3 registers, 2 input registers (B and C) and one output register (D). When for example an ADD ...
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MVC - Do I create 'joint' layers when dealing with multiple models?

I'm new to MVC and the different layers architecture and this is what I have currently: 2 models: User, Company 2 service layers: UserService, CompanyService 2 interfaces which abstract the ...
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Design pattern to holds API exchanges? [closed]

I'm developing a simple application that crawls in web pages to obtain some information. For this I used and tested some libraries, like crawler4j, jsoup, jaunt and htmlunit. I exchanged several ...
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Is there a term for splitting a function into “prep” and “do” halves?

I'm revisiting old code, and I noticed that the main logic is in one method, which is longer than I'd like (~60 lines). So I split it, and there's a natural seam on which to do so: the first half ...
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File based communication vs Rest or RPC

My company make automation machines (with a PC inside and a custom built software to control it). So, for the purpose of this question, we can say that these are normal PCs. Sometimes we have the ...
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8answers
675 views

Can “return this” pattern be optimized to no cost performance?

return this (or similar construct) allows method chaining. Lack of it is painful, because you have to write such code (C#): var list = new List<string>(); list.Add("hello"); list.Add("world"); ...
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JavaScript & AngularJs Modules Implementation technique and structure

So Im building an app and I'm trying to implement the structure of the app so that its robust and scalable in future. My app is mostly divided into JavaScript Modules (revealing pattern): // filter....
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Is IntentService an implementation of Command Pattern?

According to Wikipedia: In object-oriented programming, the command pattern is a behavioral design pattern in which an object is used to encapsulate all information needed to perform an action or ...