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

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What is the correct place to put checking of conditions in this use case?

Here is the situation: I have a database and a class that is basically a representation of a set of fields of different tables in it. Let's call it Message. "Message" does not know of the database ...
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58 views

Which is the preferable design for my Gateway?

I'm writing a Gateway class that extracts information from a HTML document. One of the responsibilities of the class is to traverse a table in the document and extract data from its rows. I'm trying ...
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90 views

Environment that enables variable constraint checking and creation

Currently I'm working on a system that enables users to add Tag's to available TagTypes on specific pages. For instance, we would have a TagType called "Installer" and the user wants his name ...
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144 views

Menu building pattern

I'm having troubles getting my head around the active-state handling of a menu when the menu isn't used for routing. I come from Drupal where the menu system handles the routing as well. so setting ...
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548 views

Fluent interface implementation and reflection. Case study

I hope I picked the right group for this question... I have this little framework I want to implement and I would like to have an opinion on it. In particular I am more concerned about the ...
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65 views

Seperate settings and implementation class hierarchies

We use XML serialization to store class settings. Each setting-class has (but doesn't reference) corresponding implementation-class. Therefore we can easily make a "settings dll" without any ...
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39 views

Go - idioms/design for determining when an unknown number of goroutines are complete

I have a workflow wherein I walk recursively through a bunch of directories, then for each file perform some action. I'm using goroutines to walk each directory, and also to process each file. The ...
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119 views

is this a valid javascript design pattern when many instances are required?

I have some code that I'm refactoring, right now its just a list of functions, primarily jQuery. The code is a form builder. The user adds sections, questions etc using jqueryUI drag/drop/sort. They ...
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193 views

What is the relationship between “flux” and pure functional reactive programming?

Flux, as far as I understood, is a technique about dealing with the dataflow of an application unidirectionally, keeping state isolated from the rest of the program in read-only, self-contained ...
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146 views

Hierarchical ViewModels and tracking IsDirty/PropertyChanged events

I have a set of ViewModels depicted like in the below picture. And, I have a couple of commands AcceptCommand, CancelCommand in the Top Level View Model that are bound to Apply, Cancel buttons ...
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63 views

What design pattern is used in this delegating scenario?

I am currently having to bend some framework API to fit my usecase. The framework provides generic interfaces such as public interface Processor<T> { T process(T t); } with various ...
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73 views

Injecting data processing logic into class

I want find more elegant and appreciate way to inject processors into CommandProcessorDispatcher class. Or it can be another one solution (the goal is separate each command processing logic to ...
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241 views

C# structure needed for dynamic behaviour

I am using Unity to build a visualisation of a serious game. I am using the C# programming language. My problem is that I receive data from a JSON and I parse it and I end up with a list of different ...
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155 views

Callback pattern handling exceptions - Best practices in .NET 3.5

I am looking to implement the callback pattern with error handling such that error is caught and pass to the callback code with the response. Since I am using .NET 3.5, I cant use Task (TAP) pattern ...
2
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193 views

How can I put multiple hierarchical forms in a single web page and avoid making it a mess?

We are a group of developers working on a web application that accepts forms filled and sent by our users and present it in an overall view. Our main form view looks like this: There are multiple ...
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71 views

Pattern for data types that are related yet fundamentally different in utility

Background I'm currently working on a codebase for what is to become a forthcoming website's content "engine", where it will take in different types of standardized data (implemented with XML), parse ...
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44 views

How do I differentiate between old and new data in backbone collections?

A common pattern I come across is a backbone collection which is initially seeded from a database. However, the user can also add to the collection. When the user does add to the collection, these ...
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736 views

What's the best way to expose a Model object in a ViewModel?

In a WPF MVVM application, I exposed my model object into my viewModel by creating an instance of Model class (which cause dependency) into ViewModel. Instead of creating separate VM properties, I ...
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94 views

Processing a list of atomic operations, allowing for interruptions

I'm looking for a design pattern that addresses the following situation: There exists a list of tasks that must be processed. Tasks may be added at any time. Each task is wholly independent from all ...
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31 views

PaypalCheckout object is composed of PaypalQuery objects. Hide PaypalQuery objects to users of PaypalCheckout?

I have a PaypalCheckout object that handles the checkout process: from initiating API calls, to providing an interface for front-end code (e.g. View/Controller). The PaypalCheckout object handles: ...
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120 views

Run a function when a function in a list is executed?

Goal: I'm currently doing an MVC project and I have this method to update the ViewBag (based on previous actions of the user). I would like to call this function whenever a certain list of MVC Actions ...
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193 views

Which are the best ways to organize view hierarchies in GUI interfaces?

I'm currently trying to figure out the best techniques for organizing GUI view hierarchies, that is dividing a window into several panels which are in turn divided into other components. I've given a ...
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28 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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110 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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106 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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156 views

Choosing the right design pattern/architecture for a scenario

I have a situation, in which I would like your opinion about the best approach that I should take. Let's consider 10 classes (obj001, obj002 etc.) all which represent some business entities, and are ...
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87 views

Concurrent directory-tree search

I am trying to get familiar with concurrent programming, and have picked up an excercise to use a fixed number of threads that search through a directory structure. This is pretty much the way it is ...
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102 views

Mailbox Pattern with Variable Arguments in C++

In a game I'm developing, the GUI thread is catching user actions, and the simulation thread is responsible of handling and responding to them. To minimize complexity and delay, I predefined all ...
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200 views

Transaction Management in Hibernate with DAO Design Pattern

I have many Tables, For every Table,we have DAO Interface and DAOImplementation class. Example DAO Interface public interface CancelPolicyDAO { public CancelPolicy insertCancelPolicy(CancelPolicy ...
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108 views

Generalization of phase based systems for card and board games

In an exercise of futility I'm trying to abstract and generalize a framework where to build any turn/rule based system. I've had a head start but after decompiling HearthStone I'm second-guessing that ...
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57 views

Choosing a pattern for domain logic on top of ORM model

I am using Python and ORM, particular SQLAlchmey. I have an ORM model which implements data mapper pattern. The model has a field state, which can take one of several states, let's say NEW, CANCELLED, ...
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54 views

How to clean composition root from anything other than object construction?

I'm doing poor man's DI (manual injection) in my application. My (pseudo-) composition root looks something like this: var connectionSettings = new Settings(SqlParameters) var dataLoader = new ...
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146 views

Am I following a good design thought process? Is the Abp framework overkill?

As I finish one project and start another, I have a small time window to come up with an architecture for the new. I am coming from the following design: Web applicationReceives domain models & ...
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123 views

The finer points of HMVC

I'm new to HMVC and whilst tutorials are great about dealing with the overall details of keeping modules separate and only letting controllers communicate, they aren't so great at explaining the ...
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258 views

ZeroMQ and Majordomo protocol

I am learning ZeroMQ and came across the Majordomo Protocol. I am wondering if I'm understanding this correctly, is the use case the same as.. for example.. the Microsoft Azure AppFabric service? ...
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172 views

What is a good way to structure my UI classes?

So, I have a program which has a swing GUI. (Java - duh!) I really, really don't think the way I'm structuring my classes now is good, so I am reorganizing from the ground up to follow best practices. ...
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93 views

How to validate information on server without using database or session

Each user has multiple sites they can access reporting data for in an application I am working on. To prevent having to go to the database on every single request, I validate that they have access to ...
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32 views

Passing configuration to a handler

I'm building my own JET Parser and one of the things I am trying to do as per the JET specifications is to allow changing of the start and end tags from the default <% and %>. Right now I have ...
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227 views

NCurses, scrolling of multiline items, “current item” pointer and “selected items”

I am looking for hints/ideas for the best (most effective) way on how to scroll multi-line items as well as emphasizing of the "current item" and "selected items" such as: 1 FOO ITEM 1 Foo sub-item ...
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64 views

Modelling network and persistent entity representations

I have an app where I need to synchronize some entities (simply download latest versions of entities from server to client). Entity has bunch of text properties and bunch of resource links (referenced ...
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79 views

Creating classes according to a struct

I get a array via SOAP service, in the array in each value which is a struct is a description of any visual components (size, position, default value etc.) like CheckBox, RadioButton etc. And I wonder ...
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173 views

Pattern or solution for using classes with different interface the same way

What I would like to achieve is to use classes (now two, later more) with different interface the same way, so I would like avoid using decisions based on the interface on upper levels for instance, I ...
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127 views

Using a Finite State Machine for access management?

My intranet site uses LDAP and Active Directory to authenticate users. There are 2 kinds of Users: Managers and Employees. They are differentiated by having membership in a particular AD group. In an ...
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180 views

Build filter conditions for entities on client side

I have the requirement that users should be able to specify filter conditions for one kind of entity through a GUI on a thin client. These conditions must be convenient to generate, meaning the GUI ...
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41 views

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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48 views

MVVM with multiple view models that share a model

I have an application where there is an "inventor" model whose data I would like to display differently in different areas of the application. Therefore, I'd like to create different view models ...
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17 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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37 views

Is there a good pattern for building nested form objects with validations?

I'm using the form object pattern to handle data normalization and validation in my app. It's working well for simple cases, but some of my form objects are composites (or roll-ups) of multiple other ...
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What's the difference between Transaction Script and Service Objects?

Recently I saw so many people talk about Transaction Script and Service Objects. For example, the Transaction Script in this article: The glory of Transaction Script is its simplicity. Organizing ...
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56 views

Haskell + OpenGL framework

I'm writing a framework in Haskell where I'd like to use OpenGL to draw lines, shapes... I'm encountering a problem defining the structure of my program. I have for example a Polyline type which holds ...