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

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How to design member access for an Article-type class? [duplicate]

I am doing a final project in a C++ class writing a very simple usenet-like client/server. I figure that since it's usenet-like I'll have a NewsGroup class and an Article class, I'm now working on my ...
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282 views

Design pattern for sharing Social Authentication across subdomains?

Right now building an app that authenticates using either email or different social accounts. Because it is going to function on multiple subdomains and domains, I'm wondering if there's a design ...
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641 views

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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187 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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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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310 views

Is there a good design pattern for this messaging class?

Is there a good design pattern for this? I want to create a messaging class. The class will be passed: the type of message (eg. signup, signup confirmation, password reminder etc) the client's id ...
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143 views

Am I missing a pattern?

I have a class that is a singleton and off of the singleton are properties that hold the instances of all the performance counters in my application. public interface IPerformanceCounters { ...
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317 views

What is the best way to compose an object with components across two assemblies?

In my project, I have a collection of classes. These classes for the most part contain data which is updated infrequently or not at all - that is they don't really do much - their purpose is to be ...
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608 views

Central Exception Handler

Recently I've been thinking about a general ExceptionHandler, that I could initialize once in my app context and inject it everywhere. The idea that it will have quite simple interface with just ...
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241 views

“Best fit” to avoid reuse of object instances in a collection

Imagine I have a collection of object instances which represent activities for a user to undertake. Dependent on user attributes, I have to randomly select instances to present activities to the user....
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441 views

How can I bind an interface to a class decided by an xml or database configuration at the launch of the application?

I'm re-working on the design of an existing application which is build using WebForms. Currently the plan is to work it into a MVP pattern application while using Ninject as the IoC container. The ...
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361 views

design pattern advice: graph -> computation

I have a domain model, persisted in a database, which represents a graph. A graph consists of nodes (e.g. NodeTypeA, NodeTypeB) which are connected via branches. The two generic elements (nodes and ...
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How can I implement a database TableView like thing in C++?

How can I implement a TableView like thing in C++? I want to emulating a tiny relation database like thing in C++. I have data tables, and I want to transform it somehow, so I need a TableView like ...
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225 views

How to control messages to the same port from different emitters?

Scene: A company has many factories X, each emits a message to the same receive port in a Biztalk server Y; if all messages are processed without much delay, each will trigger an outgoing message to ...
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1k views

Modular Database Structures

I have been examining the code base we use in work and I am worried about the size the packages have grown to. The actual code is modular, procedures have been broken down into small functional (and ...
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1answer
565 views

MVC, Java Design Pratices, and Flaws of java.util.Observable and java.util.Observer

I am planning learning Model-View-Controller (MVC) development using Java. While reading I came across a post which mentions java.util.Observer and java.util.Observable for MVC development. As I ...
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432 views

Request / Reply , how should one initiate the actual sending of the transmission?

I'm working on Language level interfaces to web API's. These libraries are of course built around existing HTTP Request/Reply interfaces. I see myself as having a few options submit method on the ...
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1answer
202 views

Publish/Subscribe/Request for exchange of big, complex, and confidential data?

I am working on a project where a website needs to exchange complex and confidential (and thus encrypted) data with other systems. The data includes personal information, technical drawings, public ...
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531 views

Am I using Factory and Impl classes properly?

In my 2d destruction derby simulator I have a CargoTruck class and CargoTruckImpl that implement an interface called Truck. CargoTruck has a reference to CargoTruckImpl which is returned through the ...
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331 views

Designing controller for modular Java architecture

We are designing a system which mimics a BPEL application with sets of functional requirements such as bulk messaging, managing SLAs, error handling and so on. One of the intentions is to modularize ...
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3k views

When designing an application around Model-View-Controller (MVC), what is in your toolbox?

There are a lot of great explanations for what the Model-View-Controller design pattern is, but I am having trouble finding good resources showing how to use it in practice. So, when you are starting ...
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45 views

How to deal with different configurations with non-overlapping properties?

I am working on a project based on the Java EE technology. First I'd like to tell you what I want to achieve, then what I already tried. Task: Imagine two types of configurations, which you want to ...
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51 views

How to prevent “updating” unchanged date using Data Mappers?

In some books the implementation of Data Mappers simply update the whole row of a table using the data inside an object, but in a system is possible that two different operations update different ...
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What would you call this design pattern? MVC or PAC

I have been reading and researching about MVC, HMVC, MVP, MVVM and PAC design patterns when I came accross this article by larry garfield > MVC vs. PAC My Implementation: Think of a modular app ...
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81 views

Return values for a delete function in php

I am writing a wrapper function for database calls, and I am confused about the best way to handle the error cases. The function has only one argument, the id of the object to be deleted. I've ...
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How do I write an API that makes use of many smaller APIs?

I have a solid set of classes that do the following build tables from data and templates advanced form serialization build forms from data and templates launch overlays with forms/wizards short poll ...
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119 views

Polymorphic constants in Java

I am designing some polymorphic code to perform mathematical operations. The idea is to abstract out the underlying representation of the data, as different use cases require different representations....
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88 views

Better way to organize query methods in Android?

In my Android app I have a SQLiteHelper class that extends SQLIteOpenHelper, and takes care of things like table-creation and upgrades. SQLiteDatasource class that performs CRUD operations on the ...
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165 views

What could be the better c# design for following requirement? [closed]

I am working on creating a c# design for following requirement. I am creating this for a fitness website. I have an article (as Text) and a exercise (as Image or Videos) as the base entity. Now i ...
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74 views

Guaranteed message sending for messages of different priority for different modules

We have created a message que system using priority messages. The idea behind this is as follows: We have a list of clients. All clients know if (and what kind of priority) messages they have ...
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143 views

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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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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62 views

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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190 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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239 views

Can this be used to implement Post Redirect Get pattern?

I am trying to implement proper a Post Redirect Get on a PHP site (question is language agnostic in nature however). I thought about it, and realized that running this code on every request seems to ...
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1answer
83 views

Possible design patterns for a service that synchronizes two third party services [closed]

I am currently in the process of refactoring a web service that synchronizes two third party services. The two services do not really interact well with each other, and there is quite a bit of ...
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72 views

Function behavior dependent on the calling class [closed]

I have a base class B and several children classes of it. Every children B1, B2, B3... has a method that calls a method M of another class C. Class C has a component D (implementing an interface, ...
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191 views

Design of an online book reader

I want to design an online book reader system as a programming exercise. I wrote down the following requirements: Searching a book by title. Bookmarking a book. Mark a book as favorite. Give rating. ...
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61 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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1answer
39 views

Deploying and maintaining a script on customer's domains

I am trying to figure the best way (or just the pros and cons of various options) for delivering a service via a script which runs on the customer's site (think Google Analytics). Unlike Google ...
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1answer
48 views

Fill widget with data retrieved from internet

I want to retrieve data from internet and show them into a widget. In particular, I've a widget with a QComboBox containing some service from which I can retrieve a list of exchange markets. When I ...
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411 views

Abstract Alert Dialog Builders (Same Method Calls, Different Objects)

Currently I'm working on an Android library that creates a dialog which allows to select colors from a palette (examples at the end) and I've stumbled upon an interesting design problem. To create ...
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90 views

Pattern for passing in a field as a parameter

I'm writing a Rails app which uses ActiveRecord ORM and a Postgres DB. I've got two attributes which are similar but are separate fields in the database. The assignment and saving of these is kinda ...
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308 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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Adding fields a good use case for EAV? [duplicate]

Is being able to add fields quickly to a system a good use case for EAV? What would be the frequency or number that would justify using an EAV model?
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2answers
655 views

Is MVC controller an use case controller?

In GRASP (http://en.wikipedia.org/wiki/GRASP_(object-oriented_design) ), a controller (use case controller) is defined as: A use case controller should be used to deal with all system events of ...
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234 views

Partially Fulfilled Specification Pattern

We have a model (IPayableModel) with a boolean property indicating that a user may or may not pay for the item. A set of specifications defining criteria that would disqualify the model from payment ...
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122 views

How to to log clicks for a Pay-Per-Click software?

Let say you have a Website with advertising, and each time a user clicks on it, you want to charge an advertiser the amount he bids (basically, a pay-per-click system, like Adswords, with a different ...
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2answers
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What is the best way to create DTOs from entities and update entities from DTOs in a layered architecture?

Option 1: At first I would make a call to my service layer, which served as an API for my core domain, to get a domain object or a list of domain objects and then pass them into the assembler which ...
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563 views

Pattern for validating rules having different signatures

I have a class in charge of responding to an input event and maybe triggering another event. To decide, it has several rules to check. I'm trying to get away from a class looking like this: public ...