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

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How do I associate command objects with the right receiver?

I tried to use Command Pattern for implementing Undo and Redo in my project public abstract class Command { protected Form Receiver { set; get; } protected HtmlElement Element { set; get; } ...
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94 views

Is the observer pattern suitable when the observers are not independent of each other?

I have a class Car which has 2 properties: int price and boolean inStock. It also holds a List of abstract class State (empty class). There are 2 states which can be applied on the car and each is ...
4
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350 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 ...
4
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633 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 ...
3
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95 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 ...
3
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156 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 ...
3
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0answers
1k 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 ...
2
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76 views

Architecture design for Web API with single endpoint

Scenario: I have a situation where I need to refactor a Web service with a single API endpoint that uses complex logic to insert, update and fetch data from a database. The clients use one call, and ...
2
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49 views

Mocking third party web service

I am working on a project to create a wrapper library which will be used to interact with a web service provided by the client's IT team. The reason for this library is that we interact with this ...
2
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87 views

Building a generalized notification system: passive vs. active

Recently, I've tried my hand at building a notification system, but I quickly found that notifications are tricky things, especially in the context of building a general model. The diversity of what ...
2
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0answers
35 views

Should my application call statsd directly or should I call statsd based off logs?

I'm planning on incrementing counters in statsd based of various events within my application. I have logging in place for these events. So, from my viewpoint I have two options: Update the ...
2
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491 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 ...
2
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124 views

Separate 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 ...
2
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244 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 ...
2
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104 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 ...
2
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0answers
193 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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398 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? ...
2
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256 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 ...
2
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73 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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0answers
56 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 ...
2
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105 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 ...
2
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0answers
33 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: ...
2
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0answers
134 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 ...
2
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203 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 ...
2
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360 views

How should Object Model wrapper classes behave when underlying objects are deleted?

I'm currently building an object model library for use in a project. It wraps our internal concepts - Servers, Folders, Items - in an object hierarchy (IFolder, IItem, etc), and we have several ...
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99 views

How to authentication user in REST API (domain driven design)

I am using REST API as a presentation layer of a DDD project. In order to secure API calls I am using token based security. ...
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68 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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75 views

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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61 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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108 views

Option<T> functional type implementation and scenarios

Have you ever being implementing Option<T> functional type? It is discussed here: https://app.pluralsight.com/library/courses/tactical-design-patterns-dot-net-control-flow/table-of-contents ...
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178 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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55 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 ...
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0answers
353 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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216 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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120 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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221 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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91 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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0answers
200 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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299 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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146 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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0answers
61 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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63 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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198 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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153 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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0answers
260 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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160 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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0answers
35 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 ...
1
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0answers
327 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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72 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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0answers
129 views

Looking for design pattern to represent shared state in music sequencer

I like to give lots of context, but also to state the basic question up top as concisely as possible. Feel free to read a little or a lot. I'm working on a music sequencer, and have been happy so far ...