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

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Understanding Flux pattern

I'm actually studying the flux pattern and there's something that I can't understand concerning the stores. What are they exactly? I have read many articles, and it seems that it concerns the ...
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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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152 views

How to avoid tying these two methods together with global mutable state?

I'm in the process of reading Code Complete 2 and learned that using global state is a no-no. What can I do to avoid using global state in this situation? Some background information: I have two ...
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How to compress and send 36,864,000 numbers per second over a network? [on hold]

You have a 3D mesh made up of 307,200 vertices. Or to put it in programming terms, you have an array with 307,200 entries whereas each entry is an object containing the properties id, x, y and z, each ...
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How to authenticate against an API?

In a enterprise distributed system, a user of a web portal can sign into one site, be redirected to a federation provider. Once they log in with, for example, a facebook account, that user is ...
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How to simplify structure of a monitoring software that uses the Observer pattern?

I am working on a project where I have to monitor the status of an elevator. So far, my design looks like this: We are using a third party library to read and monitor real-time values from the ...
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2answers
411 views

How to use SOLID principles in this example

I have reading about SOLID principles last week and decided to try to solve real world problem by using them. So I got the problem of real world ecommerce site managing totals. Problem Statement: ...
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143 views

Is there a design pattern for managing deep many-to-many relationships?

I'm having trouble defining this data pattern I've come across working on several applications. It consists of: An object type which is composed of many objects itself A second object type, where ...
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Optional features: default method or separated interface

Dedicated interfaces seems to be a good way to expose the optional features in a domain-specific type hierarchy. However, they impede the use of decorator and composite patterns, which is also common ...
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Clean Architecture - How to go from “Database Driven” to “Independent of Database” [on hold]

I am looking for some clarity and hopefully some advice on writing clean architecture for a large system. My Companies "Web Solution" is +-10 years old, my job is to rewrite it. It is written across a ...
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1answer
140 views

Is it a good idea to have separate UI components make their own webservice calls?

I have few UI components in an angularjs web-application. Each display data based upon same input. One shows stats which are calculated on the basis of a time period. Other shows a chart of daily ...
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Android: Pattern for checking requirements at startup?

My app's launcher activity checks a bunch of requirements like whether GPS is enabled, there's a network connection, the app has device administrator privileges, etc. Some of these checks display ...
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127 views

Repository pattern with service layer - too much separation?

I have an MVC site which uses the repository pattern. I don't feel like I'm using the MVC style enough, so I'm getting ready to re-architect some of it. But I'm also wanting to do it so if the ...
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208 views

in trouble making a card game with pygame

I am designing a card game playable against the computer. The rule is very simple Both player and CPU gets 10 cards of 1 to 10. Player and CPU plays a single card at the same time, every round. The ...
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Builder Design Pattern : Accessing/Passing model data in/to Concrete classes [closed]

First of all Sorry for question if its completely wrong, i am new to Design Patterns. I asked this question here also ...
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3answers
119 views

DDD design question

I have a question on modelling an Entity\Aggregate root in DDD. I am refactoring a project that uses Entity Framework and business logic as services, the services contain lot of logic which I believe ...
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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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When applying the interface segregation, should you separate interfaces for regular setters and mathematical operations?

When applying the interface segregation, should you have separate interfaces for a straightforward setters and interfaces that perform an operation before setting? For example, say you have a class: ...
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Flux Pattern dispatcher broadcast

I'm trying to get a better understanding of the flux pattern Facebook introduced a while ago. From what I understand the dispatchers dispatches every payload to all registered callbacks. Does anyone ...
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136 views

Design pattern for mapping data fields

I have seen this problem a few times and never can come up with a solution i like. System A Sales Order Entity order_id created line_items_count System B Sales Order ...
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Modelling a parcel management application

Scenario/Context: I am working on an application which would find out the highest volume of parcel delivery based on the pin code of a particular area by reading a text file which has the list of ...
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Design pattern for ensuring the “signature” of generic lists is equal

I have an interface, Attribute, that is going to be implemented in various ways, class AttributeA implements Attribute{\\..} class AttributeB implements Attribute{\\..} Then I'm planning to have ...
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2answers
372 views

Sharing code logic between controllers, through the Model layer?

As I originally conceived my Model layer, it was only supposed to hold data and no code. I receive DTOs from web-services, they are mapped into my Model objects. Those model objects usually end up ...
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657 views

Is factory pattern a right pattern for the situation described here?

Is factory pattern a right pattern when we want to consolidate the related objects? Problem - In the Set-top box, I have a user-io, basically the interface to control the settop box - The user-io can ...
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1answer
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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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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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Good practice for holding immutable data

I'm wondering what is the best practice for holding immutable data, more specifically in C#. For instance, lets say I have an immutable object called Foo. public sealed class Foo { public int ...
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Design pattern for user-roles on MVC, following SRP [closed]

I'm working on an application with 3 types of roles. Some roles may view the same data, and perform the same actions; but also differ in some other view or actions. Following SRP, I'm used to see a ...
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275 views

When do I reuse or create a new Builder

I've implemented a Builder Pattern in a project I'm working on. I'm using this design pattern to created Fields and Components (div, tables, panel (boostrap)). So I have a Director Component class. ...
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364 views

Change routing to comply with Law of Demeter

I have a Task, Owner and Plan. Charge values are kept in a plan, owner is on a particular plan and task knows its owner. A task needs to setup its charges based on the knowledge the owner has. Owner ...
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Why use Android Fragments?

I have read the documentation and some other questions' threads about this topic and I don't really feel convinced; I don't see clearly the limits of use of this technique. Fragments are now seen as ...
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DRY principle in good practices?

I am trying to follow the DRY principle in my programming as hard as I can. Recently I have been learning design patterns in OOP and I have ended up repeating myself quite a bunch. I have created a ...
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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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Where to put the Country Table?

It might sounds like a silly question but here is my problem. We have 100s of databases and in each of those databases, there is a country table. It was ok this way but we ran into minor problems at ...
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How to better isolate JOGL or LWJGL3 dependency from game clients?

I'm currently working on a project to develop a relatively small framework with the goal of supporting game development efforts for students in a course. The scope of this project is an OpenGL-based ...
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Strategy pattern and “Is a” relationship

Imagine, I have class IAlgo which is an interface. I have derived from him and implemented his single method called matchCount in different implementations - AlgoA1, AlgoA2, AlgoA3, AlgoB1, AlgoB2. ...
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Issues deciding on approach to create object

I'm trying to decide what's the best approach to instantiate a particular class. Basically there are two use cases for it: instantiate it in order to save a new entry to the database and fetch an ...
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79 views

How to design resilient web service clients?

I am writing an app that is supposed to talk to a web service. Let's say it's a chat app. It would need to receive a stream of new messages (so that they are pushed to the interface as quickly as ...
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1answer
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Is this a good implementation of the builder pattern? [closed]

I'm trying to design an SQL builder in PHP. I'm trying to make it so that the system could work with different database systems (e.g. Oracle, MySQL, MSSQL). Here's what I've got so far. First, I have ...
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40 views

Securing HTML/JavaScript only web app / JAX-RS Backend [closed]

I am prototyping a small web app where the frontend will be a pure HTML+JavaScript+JQuery which consumes services from a JAX-RS backend. The application has started to have a shape now but I find ...
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1answer
531 views

Which patterns/architecture to apply for “Import Data, Process Data, Export Result”

I was wondering which architecture/patterns to choose for the following problem divided into three steps: Import TestScript Description from File (e.g. .xls, .txt) Process Described TestScript ...
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How to understand if a property is a member of a class or I have to create a different class that holds it?

Sometimes when you create a class you can add there several properties (new data members) that you are not certain if you want to do or not. For example, I have a casino slots game. I have tiles and ...
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1answer
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UI Design patterns for non-screen based project

I'm working on a small project coded in Python that uses a single button for input and a RGB LED as feedback, which responds to button presses and asynchronous events from the network. As the ...
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2answers
167 views

Persisting Large/Complex Entities with the Command Pattern — Am I doing it right?

I am in the process of designing and building a large-scale inventory management software-as-a-service that will, hopefully, live a long and fruitful life. Therefore I am exerting a lot of effort ...
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1answer
61 views

For DI, where to create dependencies (new objects) specifically within framework code?

Basic requirement I'm making a framework for learning purposes (and likely usage on personal sites). I'm using dependency injection in classes and I'm trying to design where would be a good place ...
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What is the “Free Monad + Interpreter” pattern?

I've seen people talking about Free Monad with Interpreter, particularly in the context of data-access. What is this pattern? When might I want to use it? How does it work, and how would I implement ...
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1answer
269 views

Design patterns for navigation between pages on mobile platforms

I'd like to ask you about the best way of handling navigation between pages/activities on mobile platforms. To be more specific - about handling state in more complex apps, about handling 'Back' ...
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181 views

DI container with multiple instances of same object

I'm looking for idea to make a DI container that can store multiple instances of the same object. Usually, a DI container should store either a single instance of the object, or create new object each ...
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Where and how to reference composite MVP components?

I am learning about the MVP (Model-View-Presenter) Passive View flavour of MVC. I intend to expose events from view interfaces rather than using the observer pattern to remove explicit coupling with ...
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239 views

How can I decouple query and context in a “query object” scenario?

I'm using a query object pattern (similar to this) to manage disparate queries while avoiding bloaded facades/repositories. A query object takes a number of constructor parameters, representing query ...