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

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Context class in Strategy pattern

I'm trying to understand the strategy pattern and asking myself: is the context class must-have or can I leave it out without compromising pattern's purpose ? I was under the impression I needed some ...
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Parallelization: Choice of communication model

Disclaimer: If you're not into parallelization (on clusters), this question is probably not interesting to you and probably not worth a read. TL;DR: I search for a communication model (preferably ...
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433 views

What is a practical level of abstraction in a web application? [closed]

(Originally asked on StackOverflow - http://stackoverflow.com/questions/14896121/what-is-a-practical-level-of-abstraction-in-a-web-application) I still consider myself a newcomer to OO programming, ...
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Should I split out synchronization from my class and what's it called?

When thinking about testability and modular code, I recently thought about whether I should split out the synchronization part of a class from the actual behavior part. By example: The app "needs" ...
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Is this an implementation of the promise pattern?

I am writing a library in C++ (making use of many C++11 features) that (as far as I can tell) implements the promise pattern. The library consists of a class that makes asynchronous network requests. ...
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A design pattern for data binding an object (with subclasses) to asp.net user control

I have an abstract class called Address and I am deriving three classes ; HomeAddress, Work Address, NextOfKin address. My idea is to bind this to a usercontrol and based on the type of Address it ...
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How to avoid “managers” in my code

I'm currently re-designing my Entity System, for C++, and I have a lot of Managers. In my design, I have these classes, in order to tie my library together. I've heard a lot of bad things when it ...
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4answers
564 views

Applying DRY to an inheritance hierarchy

I'm working on refactoring a legacy application where I implemented the State pattern successfully as shown in the following diagram: As you see there is a common behavior between the 3 states, so ...
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Is it reasonable to build applications (not games) using a component-entity-system architecture?

I know that when building applications (native or web) such as those in the Apple AppStore or Google Play app store that it's very common to use a Model-View-Controller architecture. However, is it ...
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181 views

Possible Designs for code block editor

I have started a project where I need to design an application that will work as a code-block editor, much like lego mindstorms and this google project. http://code.google.com/p/blockly/ What are the ...
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846 views

In MVP, should presenters instantiate and control other presenters?

I've implemented an application using MVP with GWT, which is working out very nicely for views that have a single purpose. Now, it has evolved into views that are achieving multiple purposes in a ...
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Design Pattern for enterprise application

I read few articles about composite pattern and I want to know whether its applicable in following situation, I found that "A Composite Entity object can represent a coarse-grained object and all its ...
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Should we validate a state transition before attempting it in the State Pattern?

When applying the State Pattern illegal transitions should result in an exception being thrown (or at least that's what I understood from the pattern) I know exceptions are for "unexpected behavior" ...
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Design Pattern For Util Classes and General Static Variables

I am developing a Mojo(think it as just a usual class) for my custom Maven Plugin. There is an Abstract Mojo at top. I have some other custom Mojos in example which makes server side includes. I have ...
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3answers
840 views

Why don't we use a class and its static members to do what a singleton does?

In Java,C++,Objective C, C#, and all other similar OOP languages, Why don't we use a class with static methods and vars instead of going through a singleton syntax having to deal with various ...
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4answers
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What the right pattern to Use here

scenario: I have an entity called Member. Members fall into multiple types. Some types are below. Supporter Volunteer Sponsor Player I can create class for each type and inherit from the base ...
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1answer
555 views

Shift Javascript framework - What pattern is this? MVP, MVC or something else [closed]

I have created a very tiny framework to be able to get away from all the clutter while developing. The point of the framework is not to replace any library of choice but simply segregate the code to ...
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3answers
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Is it a good idea to register views and view models as singletons in an IOC container?

I understand the benefits of injecting dependencies into objects, but have not found much guidance on the types of objects to inject and when to make them singletons. If we take as as example an ...
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Bridge Design Pattern - I still don't get it [duplicate]

Possible Duplicate: Understanding the bridge design pattern I have read lots of material about the bridge design pattern: http://www.codeproject.com/Articles/3151/Illustrated-GOF-Design-...
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Abstracting out a module or using the Module Singleton directly?

I am working on a module which is dependent on other module for some functionality. Now the dependent module provides a lot of functionality and I need only few of them, hence got the idea to create ...
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4answers
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Design pattern for polymorphic behaviour while allowing library separation

Let's say I have a hierarchy of Item classes: Rectangle, Circle, Triangle. I want to be able to draw them, so my first possibility is add a virtual Draw() method to each: class Item { public: ...
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2answers
245 views

Changing __class__ in a factory?

I'm parsing a set of XML files of different kinds (these kinds are known in advance). These are my requirements: I want an object to represent each XML document (object-xml mapping) I'd rather ...
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In MVC, can/should basic data retrieval from the Model be done in the View?

Given the concept of 'skinny controllers, fat models' and the general acceptance that Views can directly call on Models when requiring data for output, should one consider handling the 'get and ...
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What is the purpose of NaN boxing?

Reading 21st Century C I arrived at chapter 6 at the section "Marking Exceptional Numeric Values with NaNs", where it explains the use of the bits in the mantissa to store some arbitrary bit patterns, ...
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POST/Redirect/GET with invalid form submission?

In the field of web development, is it good practice to do a POST/Redirect/GET when fields in a form submission are invalid, as well? Typically, no sensitive transaction would have taken place, in ...
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1answer
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Design pattern for object conversion (java)

I don't use design patterns very often, besides an occasional factory and MVC, and I want to start using them more. I have a concrete case at hand that I would like your opinion on the use of design ...
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Visitor stability vs instanceof flexibility

I am working on a GUI application which generates a configuration file. I have a class hierarchy for the configuration model and I use an object tree of that hierarchy in several different contexts. ...
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Hacking Python “Requests” library.. How to start as an intermediate pythonista?

My question is conceptual, yet extremely vital for me. I'm an intermediate Python developer. I know fair enough about it, and actually use it on a daily basis. Now, I would like to transform my ...
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Service layer design

I am developing an MVC website in PHP, and for the first time, I would like to implement a service layer. I have some design considerations I would like to get some advice on. The backend will by no ...
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Determining which decorator classes are available via reflection

I'm creating a pizza place application where employees will be able to create orders for customers(pizza and any number of toppings). This is for a school project but the requirements have nothing to ...
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terms for the html/css/javascript model?

Are there any words for the design model implemented by HTML + CSS + JavaScript, either for that specific set of technologies or any abstract pattern that they follow?
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616 views

Class structure/pattern for validating several different Excel templates?

I'm trying to validate the contents of Excel sheets that follow several different templates. For each one, there are three possible validation actions for various cells: Regex (e.g. "XYZ-123" fails ...
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5answers
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success:/failure: blocks vs completion: block

I see two common patterns for blocks in Objective-C. One is a pair of success:/failure: blocks, the other is a single completion: block. For example, lets say I have a task that will return an object ...
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How to make an ASP.NET MVC site modular

I'm in the planning stage for an employee intranet system to be built with ASP.NET MVC 4. We'd like the site to consist of separate "modules", each of which provides a different feature: messaging, ...
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Implementing the command pattern in a RESTful API

I'm in the process of designing an HTTP API, hopefully making it as RESTful as possible. There are some actions which functionality spreads over a few resources, and sometime needs to be undone. I ...
11
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3answers
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Is using unit tests to tell a story a good idea?

So, I have an authentication module I wrote some time ago. Now I'm seeing the errors of my way and writing unit tests for it. While writing unit tests, I have a hard time coming up with good names and ...
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1answer
600 views

How do we structure our JavaScript so that it is easily editable, testable, and can make calls to render a view without knowing specifics about it?

I am working on a web application that displays some data and uses JavaScript. Right now, we are serving up parts of our JavaScript code (to display certain types of information, that is, "Render a ...
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What is an Anti-Corruption layer, and how is it used?

I'm trying to figure out what the Anti-Corruption layer really means. I know that it's a way to transition/work around legacy code or bad APIs. What I don't understand is how it works and what makes ...
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3answers
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How to design website workflow?

I have been thinking about this for really long time without reaching an optimum answer. First of all, I'm a medical doctor who loves programming but never really studied it, except for home learning ...
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1answer
598 views

Does it make sense to create a Ruby wrapper to reference a Java object that does exactly the same thing?

I am using JRuby. In my Java code, I have a class called Texture, capable of doing some graphic manipulation stuff. In my Ruby code, I will usually need to draw things, so though I should simply ...
11
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1answer
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Are we using the repository pattern right?

We are using a bunch of separate classes suffixed with -repository to retrieve the data from the database; for each table its own repository. We have for instance a customerrepository class which has ...
27
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MVCS - Model View Controller Store

I recently decided to start learning iOS Development, and to this end I’ve been reading iOS Programming: The Big Nerd Ranch Guide. In the book the authors describe a design pattern MVCS - Model-View-...
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4answers
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Is there something like a polymorphic Singleton?

I have a resource loader object that loads objects from the disk or from a ZIP archive, depending on the platform. It has state (e.g. the path to the directory or the ZIP archive, and possibly some ...
4
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3answers
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Is there a design pattern to solve this problem?

I've been struggling with a design so I figured I'd ask here and see if anyone's able to help :) High level overview I'm designing an app to gamify exercise by creating mini competitions (ex. Who ...
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1answer
312 views

In JSF where do objects like PhaseListeners fit in the MVC pattern?

When it comes to JSF, I've had trouble distinguishing where certain objects I create fit into the overall MVC pattern. The View is simple enough since that's handled by the .xhtml template but when ...
3
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1answer
770 views

Java Logfile Parsing Assistance

I'm writing a log parser that continuously looks for specific patterns and then fires off events to another system when it finds these matches. The firing of the event is time critical to catch errors ...
9
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3answers
4k views

How do you handle multiple users editing the same piece of data in a webapp?

There's a project I'm working on that is looking to produce a web application that will manage a task list between multiple users. This is a master task list whose task items get distributed by an ...
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1answer
90 views

How to get a reference to a central AssetLoader in every Widget?

I'm working on a simple UI system for a game. The building blocks are Widget objects, which can contain each other. There are several sub classes of Widget, e.g. LabelWidget, ImageWidgetand ...
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7answers
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Is the use of security conditionals in a view a violation of MVC?

Often what's displayed to a user (e.g. on a web page) will be based partly on security checks. I usually consider user-level / ACL security to be part of the business logic of a system. If a view ...
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How to refactor “nested” view classes to avoid deep method calls?

Lets say I'm displaying a bunch of data (model) using a View class for rendering. However, a lot of the data has sub-data (models) complicated enough to require separate rendering classes. In my ...