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

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Tips for working with badly designed software [closed]

Currently in my job im working with a lot of older php systems which don't follow normalised design patterns and are frankly, a mess. As an ethical developer and someone who always strives to better ...
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646 views

What is this design pattern called? [closed]

I have some code: /// <summary> /// Represents Record Locator class /// </summary> public class RecordLocator : IRecordLocator { /// <summary> /// The Record Locator string, ...
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348 views

Is it better to find issues myself or let the computer figure it out?

I'm about to start the process of migrating a program from one component to another. Most of the core functionality will be the same but I'll need to change database calls, etc. I'm sure there will ...
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Design pattern for a multi-threaded URL fetcher in java

I'm looking for hints and suggestions on a design for a multi-threaded URL fetcher in java. Specific requirements are: To fetch each one of around 1,000 URLs periodically The interval between each ...
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299 views

Is testability and mockability really that important in web development?

I'm reading this series on Laravel, and it's in great depth dealing with making everything testable, using Repository instead of just using the Models, using Dependency Injection and other obscure ...
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154 views

Constructor with tons of parameters vs builder pattern

It is well know that if your class have a constructor with many parameters, say more than 4, then it is most probably a code smell. You need to reconsider if the class satisfies SRP. But what if we ...
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308 views

Is this 'implementation' of a builder pattern good design

public class MyButton{ public MyButton(){} public MyButton setIcon(Icon icon){return this;} public MyButton setText(String text){return this;} } And used like: MyButton testButton = new ...
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354 views

Does algorithm design belong to software engineering? [closed]

In academic meaning, it seems to me that algorithm design is studied in a high/abstract level of computation (computability, complexity), although software engineering is also studied in ...
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142 views

Beginner Decorator Pattern Question

I came across this article: http://sourcemaking.com/design_patterns/decorator After reading it, I am having a little bit of difficulty understanding a concept. If you look in the Structure section in ...
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283 views

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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821 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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Various methods manipulating same member variable versus each takes inputs and provides output [closed]

As software design paradigm which is better? to let various methods manipulate a member variable, or define each method or function to take some inputs and provide some outputs? For example class ...
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Developing “real” synchronization [closed]

I'm currently writing a email synchronizer application that synchronizes email to a sql server database. One direction is not a problem: Fetching folders from the server (with its messages) and ...
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1answer
179 views

Design pattern for modifying state and notifying the other modifiers without a loop

The idea is that I have a set of properties that represent possible options in the app. These options can be modified through a variety of different ways, such as from the UI, remotely, third party, ...
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1answer
211 views

Technical example of modeling a domain with OOD?

Considering favoring composition over inheritance and looking at various design patterns there are multiple approaches to modeling a domain. Say you have some Entities which are very similar in some ...
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352 views

Is the Adapter the correct design pattern for this situation?

I have an instance of a class UntouchableClass of which I need to access the member variables to use in my DotLiquid template. Problem is, UntouchableClass has to inherit from Drop if I want to use it ...
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1answer
324 views

Anemic domain models - what sort of methods a domain object might need?

This question might seem strange, but it's something I've faced sometimes. I've been trying to adopt DDD, however I'm always facing the problem of anemic domain models. The problem is that when I ...
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5answers
446 views

To which layer does this code belong?

When I say "Revisional Data Model", I mean a data model where information is never lost: Deletes never destroy any rows, and updates always cause an insert somewhere else to preserve a row's previous ...
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2answers
101 views

Which design pattern to choose when supporting multiple analytic tools?

I have spent quite some time learning all possible design patterns but I cannot find the ideal one for the following case. I am developing an iOS app where we are using multiple analytics tools like ...
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3answers
254 views

Check a boolean before setting it in a loop, or just set it

I have a rather tight loop with the following check to see if balance had ever been positive: balance_null = True while (crazy_loop()): ... if 0.0 < balance: balance_null = False ...
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1answer
172 views

How to deal with product owner who refuses to follow UI design rules

We develop Android application. We base on old version of similar application developed in our company. This old application was designed by some noobs which didn't follow UI Android design rules. ...
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261 views

Communicating between unrelated components/objects

Imagine that I have a game, with Monsters, Missions, Vehicles, and of course their controllers and such, so a Monster class, Mission Controller class, Vehicle Controller class and so on. Suppose that ...
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2answers
357 views

Is there a design pattern for dynamically applying transformations or filters to a model?

For example, there is a model of an event with certain attributes that can be adjusted by existing processes: maybe one that looks at a geo-location stamp and determines a nearby city; another that ...
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385 views

Doesn’t active record violate SRP and OCP?

I have watched the active record classes in our project grow into large, do-it-all classes. When you need anything about a user, for example, you should go to the Person class. While this makes ...
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1answer
96 views

What is the shortcoming of custom factory comparing to generic factory [closed]

I have a factory method as given below public class AutomobileFactory { Dictionary<string, ICar> internalFactory = new Dictionary<string, ICar>(); public AutomobileFactory() { ...
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2answers
888 views

Difference between Singleton pattern and auto_ptr<> resp. unique_ptr<>

I'm maintaining some legacy code of a physical simulation. The calculation object is build as a singleton, to ensure there is only one instance. A co-worker told me, that singleton are completely ...
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Subclassing to avoid line length

The standard line length of code is 80 characters per line. This is accepted and followed by the most of programmers. I working on a state machine of a character and is necessary for me follow this ...
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639 views

Changing a variable through a series of statements … What is this technique called?

I'm looking at a function that that has several statements like this: n = returnDifferentVersionOf(n); I.e., the value of the same variable n changes progressively several times during the course ...
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562 views

Object design where hard-coded values are used to instantiate objects?

I'm creating the design for a browser bookmark merging program and I've ran into a design problem that I've seen before yet I've never come up with a good solution for it. So lets say I have a ...
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1answer
5k views

Best place to write SQL queries

I've been working on this project for my company. Currently I am embedding my SQL statements inside the program itself as and when they are needed. I do have two seperate classes - QueryBuilder ...
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1k views

Designing a Web Application with Two Different Backend Databases [closed]

I'm working on a pretty standard LAMP based web application. The server itself has a standard MySQL database and the application is written in PHP. The kicker is, we also use SQL Server databases ...
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213 views

When modeling a virtual circuit board, what is the best design pattern to check for cycles?

To make it simple assume you have only AND and OR gates. Each has two inputs and one output. The output of two inputs can be used as an input for the next gate For example: A AND B -> E C AND D -> F ...
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269 views

Template rendering engine legitimate use of a singleton?

I wrote a standalone singleton class (scaffold) tonight that serves as a facade to a few other classes, including a template class and a view class. Templates and views are both named and instances ...
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168 views

What is the best practice for verify if a client has already dowloaded information from server? [closed]

I need to verify what data wasn't downloaded yet. For example, how does Twitter or Facebook verify if a specific client has already dowloaded a piece of information? When a mobile app like twitter ...
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1answer
90 views

Best practices/patterns for generation PDF reports

I have PDF generation feature in my app. I am using iTextPDF for generating reports, so it works well. The problem is not exactly in pdf generation but in approach. Currently PDF generation code looks ...
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214 views

my software model has some kind of cyclic dependency

I need a recommendation about my software model. I think it is not that good, since there is some kind of cyclic dependency. I have an OSGI bundle under Kura application framework, here are the ...
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1answer
223 views

Rich Model vs God Class [duplicate]

I have a legacy code containing some behaviour classes, like services and controllers. My model is pretty anaemic. It's just a repository of getters and setters, and I want to refactor it. There is a ...
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1answer
173 views

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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1answer
261 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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1answer
180 views

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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1answer
168 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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1answer
179 views

What should be in a PIMPL?

I am kinda trying to implement a windowing library in C++, the circumstances are forcing me to implement it all myself, that's not the point of this question however. My question is: What should be ...
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3answers
2k views

Proper Query Object Pattern - NHibernate

I was looking to an alternative to Repository Pattern and I've read about "Query object pattern" (http://lostechies.com/jimmybogard/2012/10/08/favor-query-objects-over-repositories/). However the ...
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2answers
166 views

Is there a better way to load objects?

I have always kept the code to load an object within the object itself. That way no matter what method is creating the object, it always has access to the method to load the object. However this does ...
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3answers
511 views

What is the main goal of MVVM pattern? [closed]

Could you tell me what is the goal of the MVVM pattern? What are the arguments or the reasons I can give to a team and product owner to respect and develop according to this pattern? I would like a ...
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242 views

Container/Item pattern without `friend`

I have a class Container containing objects of type Item. They are different classes, and especially they have no common base class (e.g. a Container does not itself have a Container).: class ...
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2answers
538 views

Why does the Mailbox app need their own backend?

I am only coding in Objective-C and I have no experience with backend coding, only a high-level understanding. I understand why a lot of programming projects require backend servers but I'm not ...
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3answers
381 views

Software architecture which allows for growth, real life situation [closed]

I know of Interfaces, Abstract classes that serve as Base class, I've been reading up on loose coupling, ... But I can't come up with a decent solution when a property of a class changes, and the new ...
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278 views

Best way to display domain object summary information efficiently and in an OO way from a large inheritance tree?

I've provided only simplified code as it's more of an abstract design question. So I have many, many nested business/domain event objects, e.g. public class Event { //bunch of properties and ...
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2answers
1k views

Can Dependency Injection used as an alternative to Reflection for creating instances

There is a piece of .net C# code which use Reflection to create an instance using Activator.CreateInstance(). This is an old piece of code and runs on the top of Enterprise Library. Is it a better ...