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

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Options for constructing an object that is not logically initialized until all fields are set

I am working on a Pokemon game at the moment, and am running into some design concerns. The easiest example is as follows: Each Species of Pokemon has several traits that are required before it is ...
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123 views

Global state of games(or other). Example : Waiting,Betting,Battling in gambling game

So I'm making a IRC betting bot. Basically the game/bot has three states of taking-in chat. State 1 : Betting If anyone says "!bet team money" parse it and record. State 2 : Battling Take nothing ...
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What is the efficient way to eliminate duplication? Design patterns?

I have a helper class which has a method that perform some checks against a field in a model. I have two models, ModelA and ModelB, they have some similarities but not all. One of them is they both ...
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266 views

How to solve this problem of duplicate code with a design pattern [duplicate]

This is what I am doing, Creating a new Pdf document using Aspose Pdf Adding few different types pages you know introduction page, table of content pages etc... Adding some further documents to it ...
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67 views

Application components dependency and decoupling

In my client application I have two major components: Core: wrapper that handles everything about running the actual application NetworkClient: A layer that takes care of communicating ...
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118 views

Changing an object's (apparent) class at runtime

I'm looking for a design pattern to solve the following problem: An object (let's say representing a document) can change its type dynamically during its lifetime (e.g. when it is saved with a ...
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91 views

Job and workers, pattern / design

I have x number of worker classes which all implement a specific interface, i have a job descriptions Each job description States the different worker classes that should execute to complete the job ...
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What is the correct way to bind few classes with similar functionality?

I want to do this in the right way to learn I have a few classes which have only one method. For example: public class RedColorText { public void AddRedColorText(string text) { ...
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Which Design Pattern Is Best Suited?

I have been studying Design Patterns and I am looking to implement them into my latest project. I am working on a Windows Service that regularly checks a database table for a new entry. Depending on ...
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Dependency Inversion & Decoupling

I'm wondering if someone might explain the last paragraph written in this example on Dependency Inversion & Decoupling. http://www.springbyexample.org/examples/core-concepts.html Following the ...
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Lookup pattern as a way of passing global references

I am looking at some legacy code in java that uses the Service Locator pattern as a way of passing global references as opposed to passing them over and over again through method arguments and I am ...
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Decorator design pattern in swift

Im reading "Head first design patterns" (here you can find exact example mentioned in book) While going through Decorator design pattern, everything was crisp and clear until i stumbled into this ...
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181 views

How would a modern website like Reddit divide up its website into Django apps? [closed]

Django uses apps to divide projects into manageable and reusable chunks. All examples in tutorials use polls or articles in unrelatable circumstances. In a modern example like Reddit (or even Amazon ...
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Designing interfaces to hardware

I am writing a library in C++ that is used by customers to interface with hardware. There are many different devices that I need to support. For the sake of simplicity, assume I have 2 Widgets, ...
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206 views

Service layer - fat service classes?

Let's say that I have a service for Job Offer entity in CRM app. Job offer is related to many many things, so there will be lot of methods on service layer to interact with above. What should be ...
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1answer
254 views

Repository pattern without entity framework?

Is it possible to implement the Repository pattern without using entity framework? I am working on a small dev team of 3 on a small scale (for now) ASP.NET MVC solution. I told my manager that I ...
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1answer
99 views

Software Design: Generating Documents Of Different Formats and Different Layouts

I am currently prototyping a piece software which must be able to generate different types of documents in different file formats. The document could be a letter, or a receipt, for example, requested ...
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70 views

Combining Patterns: Fluent Builder and Null Object Pattern

I am currently wrestling around with some GUI code where I have a table whose rows correspond to some object, let's say a Person object. When the table initializes, it fills the table with the Person ...
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266 views

DRYest approach to “rendering” drag-and-drop template editor results to HTML

I'm in the process of designing a browser based system that will allow non-technical users to quickly and easily change the content of certain parts of a web page via a WYSIWYG template-based ...
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Does key-value observing between model and view violate MVC?

In MVC the Controller is the go-between for the View and the Model. So the Controller should be the one that observes or receives changes from the Model and View and updates the other accordingly. I ...
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Unit testing a template class after refactoring

I am cleaning up my code by way of removing duplicates, and found two classes that were almost identical, out of 55 lines, only a single predicate in an if statement differed between them. Both ...
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Possible to refactor these methods that contain the same logical flow?

I have many methods in many repositories that have the same logical flow: Retrieve value from Cache Check value If no value, fetch from Database Update Cache Return value Is there a way to ...
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1answer
252 views

Should I use foreign keys in my database if I use laravel?

I'm creating a website with Laravel for the first time. I checked relationships documentation today and it seems that Laravel just uses simple SQL queries. class User extends Eloquent { public ...
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Ways to do callback, when and where

I've recently started to do some more complicated programming with network-related work on iOS with Swift. This introduced a lot of asynchronous code not only in networking but also some exchange of ...
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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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Flexible and easy to use settings class

I am thinking about a way to create a flexible "settings class" in C#. The question is: How to provide a confortable way to provide default values to the settings. I want the programmer to access the ...
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where should put showSchedule method in school system

In my school management system I have this partial class diagram: 1- In one use case student want to see his schedule of classes in week. this is what i suppose to do: get student object from ...
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Design solution for communicating between multiple layers

We are developing a framework that has several layers and would be deployed in a multi-threaded environment. Each layer may have its own input/output data type. The top layer takes the input, performs ...
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170 views

Design a Queuing Solution with Clustering and Multiple Consumers

It is a Design Problem which I am listing out here. I have different set of business operations that are carried out for different business entities. Operations: Operation A Operation B Operation ...
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many to many relation in database schema and oop class diagram

I have Student and Group entities. Student can have many groups and Group can have many students too. so in database I should have middle class and change many-to-many relation to one-to-many and ...
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Pattern for caching DAOs: strategy or decorator?

I'm building a php system with the Services/DAOs/Domain Models pattern, and now is the time to implement a caching system for the DAOs. Would you use a decorator pattern, or maybe the strategy ...
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245 views

How could I avoid singletons in this case? [duplicate]

Using Dart in the client part of a web app where I have an application manager that contains a List of application instances and references to services that are used by each application as in the ...
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165 views

Template pattern with varying input type in overridden method

I am trying to use template pattern to define a generic algorithm in java. But the method that needs to be overridden, takes an object as input. This object will vary depending on the concrete ...
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224 views

What design pattern for changing interface?

Sorry guys, I should have clarified the fact that the modified method is abstract in Father. Then if the method signature changes, all its implementations in SonX shall also change(at least the ...
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Is having a parent controller to manage a set of tabbed sections an anti-pattern for an angular application?

A lot of times, I have long forms that I divide into multiple tabbed sections. Each section is managed by it's own controller and there is a parent controller that manages the whole view. I use ...
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162 views

Why use a enum to create the singleton pattern [duplicate]

Why would you use an enum to create a singleton pattern? To what purpose would it serve over a conventional singleton pattern? I have seen the above used. The code uses an enum to create this pattern ...
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Applying initialization-on-demand holder idiom at variable level rather than class

I was looking for the idiomatic way to implement thread-safe lazy initialization for a configuration collection retrieved from the DB inside a Spring bean. I decided to adapt the ...
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Is this a pattern? If so, which one? (Contexts, Requests and Responses) [closed]

In most of my code nowadays, I adapted to an approach which I think I read in the context of "Clean Code". It was some years ago and I cannot find the source again, so I would like to know what the ...
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Dealing with several custom getters

I have a data structure with data units containing different types of data. I've wrapped the data in "Field" objects so that each field is able to independently parse user input in a desired way. ...
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How should I represent composeable, associative computations to be repeatedly applied to units of data?

Spoiler My question is the following: Are there any design patterns for representing chainable functions that are for the problem described below? High-Level Decription of the Process I'm ...
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Is it misleading to label code as a particular design pattern if it only loosely fits the definition?

Background: I have a rough, but working understanding of ~15 design patterns. It's been my experience using design patterns in my own projects that the resulting implementations usually end up as some ...
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100 views

Should make concrete factories in the same count of families of objects or according to stages in my problem?

I am programming a game. In this game I have 3 stages. In the first stage, there is a static goal and a static shooter in the game. In the second stage, the goal will move. And in the third one both ...
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How should I handle logger failures?

In several of our company's applications, we use a custom logger. It's fairly robust, though we may replace it with something like NLog in the future. One of the logger's tasks is to log any ...
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2answers
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Design pattern for composition workflows

Please bear with me as I find this tricky to articulate exactly what I am after (probably not a good sign..). I have several services set up which can be combined in a particular order to create ...
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1answer
175 views

When do I reuse or create a new Builder

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

Can JUnit be used to test this project?

I currently have an interesting situation occurring with my code, and after hacking away at what turned out to be a dead end for the last two weeks, I'm here asking those smarter than I to educate me ...
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122 views

Is Singleton enough for a EMailUtil or there is any better implementation? [duplicate]

I am developing an application, where I have to send lots of emails for user account creations, validation, invites etc. I have implemented a static class EMailUtil which has different methods like ...
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Is it bad to use DI to inject constructor parameters at runtime?

These are two classes, the first one I inject an instance of type IEngine while the second one I inject owner's name, tickets and engine. Version 1: public class Car { public Car(IEngine ...
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68 views

How to organize conversion logic for strategy pattern?

I have a Color class. It has a property model which is a class that implements ColorModel interface, this property could be a RGB, Hex or HSL classes which implementing ColorModel interface. // ...
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187 views

Design Pattern Question

I'm relatively new to the world of OOP, and having read through some design patterns, I'm struggling with that 'aha' moment. I have the following objects Event (Single event, with start time and end ...