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

learn more… | top users | synonyms (1)

3
votes
2answers
182 views

IoC as service locator

I have been wondering for quite some time on some issues while using dependency injection: In a layered application, I normally inject repositories into the application service using constructor ...
0
votes
0answers
48 views

Controllers passing Request objects to backend logic that forward Request data: Good or Bad?

Currently working on a server-side front-end Scala Play app that does a lot of grabbing of HTML snippets and JSON from many other web apps before piecing everything together and sending it in a ...
0
votes
3answers
144 views

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 ...
-2
votes
1answer
102 views

Learn how to write/design code in a “organic” way? [closed]

I'm an average programmer, I have not issue accomplish the most of daily task and figure out solution, instead my issue is how to design code. let me try to explain: I don't need to learn OO ...
1
vote
4answers
232 views

Design pattern name for an API wrapper class

I am writing a class that wraps (the parts of) an external API I am using. Let's take the Github API as an example. My imaginary Github class now has a fetchUser() and fetchRepository() method. When ...
3
votes
1answer
109 views

Difference between patterns: Specification, Guarding, Conditions, Monads, Validation,

I'm currently trying to get my head around a few patterns (especially the ones mentioned in the title above) that are made to address different problems and are being used in different parts of the ...
3
votes
4answers
613 views

How to force “program to an interface” without using a java Interface in java 1.6

In java 1.8 they have wonderful new "default interface methods". In 1.6 how close can we come? The goal: keep clients (using code) from being able to tell that a class is not a java interface. If ...
2
votes
4answers
318 views

Is this a commonly encountered situation in C++? Is there a pattern to handle it?

I am writing a game in C++, and something I have noticed is that I have many resource files which need to be loaded after a particular point in initialization. For example, OpenGL textures and VAOs ...
0
votes
1answer
119 views

Static methods vs Interface implementation

Here is my problem: I stared to create a e-commerce web sites info collector. So i created a parser for each site. The parser class is state less. got methods like: getItemPrice(WebElement page) ...
28
votes
8answers
6k views

When writing object-oriented code, should I always be following a design pattern?

Is there a conceivable design pattern for any object-oriented program? I ask this because recently I saw an implementation of a Door class with a Lock. It was part of a test and the answer said that ...
2
votes
1answer
103 views

Do I need EventAggregator here?

I'm learning MVVM pattern with C#, WPF and .NET Framework 4.5.1. I'm using MVVM Light framework to do it and now I have a doubt. Reading the book Windows 8 MVVM Patterns Revealed I see that the ...
0
votes
3answers
180 views

Is there a programming pattern, design pattern, or naming convention for moving data between related schemas? [closed]

I'm working on a web application that is publicly accessible. (Really) Long story short, we have two sets of tables in the database with relatively the same names and relatively the same data. The ...
0
votes
1answer
141 views

Does this diagram give a good representation of the MVVM pattern?

I am having a really hard time understanding the basic structure of the Model, View, View Model pattern. I have honestly been pretty ignorant of design pattern conventions until recently. My formal ...
3
votes
3answers
385 views

Separating Code into Smaller Files in C

I am in the process of cleaning up my code and making it easier to maintain. I am doing this by turning my 5000+ line file into separate smaller files. I have successfully created separate source and ...
0
votes
2answers
85 views

When should you create/destroy underlying object in a class that wraps it

(note: I used Java to make it easer to explain my question, but the actual language is irrelevant for this dilemma) TL; DR: I have a wrapper around some underlying class. At which point should I ...
0
votes
1answer
75 views

Strategy vs Publiser-subscriber pattern

Let's say I have a channel endpoint where I receive messages. Because I want to process messages in a different way depending on its Header property, rather than create a massive switch I create ...
0
votes
0answers
73 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 & ...
0
votes
4answers
421 views

which pattern is most intuitive for a calculator app?

The title says it all. I'm trying to build a calculator application (for self-learning purposes). The application is going to have a very common UI, with plus(+), minus(-), multiply(*) and a divide(/) ...
1
vote
1answer
135 views

Pass Event between Systems in a multi-threaded Entity-Component-System

Is there a way to pass Events between Systems in a multi-threaded Entity-Component-System that realizes the benefits of saving on system resources? I've read a german article about the ...
1
vote
2answers
130 views

How to deploy software automatically over SSH?

I am dealing with a distributed application which is going to mange a network of Linux-based servers spread among different places. Having the SSH credentials (as the most supported connection ...
3
votes
2answers
361 views

Best approach for multilingual Java Enum

I'm running into issues with an approach I am taking and am now wondering if I just started down the wrong path and should rethink my approach. Here is what I attempting. I would like to use an Enum ...
2
votes
4answers
492 views

When should something be a class? And are my chosen classes good OO design?

My background: I am new to programming. Python is my only programming knowledge. I program as a hobby, and I'm teaching myself by reading copious amounts of books. I understand enough about OOP to ...
0
votes
0answers
85 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 ...
1
vote
1answer
126 views

Are CRUD operations intended to be used with collections?

CRUD operations, by definition are... interfaces that permit users to create, remove, modify or retrieve data Implementations of CRUD interfaces can come in various shapes and sometimes they are ...
8
votes
1answer
260 views

Is this a valid design pattern for a Haskell main function?

After developing several Haskell applications I've found myself rigorously segregating impure code and failable (partial) functions from their pure & total counterparts. These efforts have ...
0
votes
0answers
34 views

Efficiently extracting data from pdf with a template system?

basically allow a user to label specific text in a pdf file. Use the label information to create a template, which a script uses to extract text from specific pdf. What would be a good pattern to use ...
3
votes
2answers
136 views

To subclass or to wrap for “default” implementation?

I'm creating a toolset in Java consisting of many Natural Language Processing (NLP) tools, such as Tokenizer, POS tagger, Lemmatizer, Sentence parsing, etc. I want to put all good and publicly ...
2
votes
1answer
92 views

Should this interpretation happen in the Controller or the Model?

Imagine an application where the user is allowed to create his/her own musical scales. The user selects notes from a list, arranges them to a group and presses a button to create the scale. In an MVC ...
2
votes
2answers
236 views

What is a good design pattern to implement REST services on mobile?

It is easy to implement calls to API endpoints, then to parse JSON and handle the data - but what is a good design pattern for this? Here are some ways I have tried but I feel like there should be a ...
2
votes
1answer
59 views

Questions about UML in relation to the command pattern

http://www.oodesign.com/command-pattern.html In reading through a tutorial about the command pattern, I came across a UML diagram that seems to omit some relationships. For the following diagram, the ...
0
votes
1answer
121 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, ...
4
votes
2answers
289 views

dealing with a very large state machine in a class

I am currently implementing a class for a network protocol. The protocol uses a quite complex and extensive finite state machine. A pair of an event plus a state is mapped to a function, which does ...
1
vote
1answer
158 views

Should the Presenter depend on the View or the vice versa?

So far, I have used the MVP architecture pattern a few times. Every now and then, I wonder whether my Presenter should depend on my View or vice versa, that is the View depends on my Presenter. NOTE ...
0
votes
5answers
370 views

Liskov Substitution and SRP Principle violation - how best to structure this scenario?

While learning SRP and LSP, I'm trying to improve the design of my code to comply best with both of these principles. I have an employee class that has a calculatePay method on it. Firstly, I believe ...
3
votes
2answers
216 views

What is the difference between a function and a component?

I just listened to Software engineering Radio podcast on components. Their description of components were very vague, they made them sound like lower level versions of functions. I am trying to figure ...
0
votes
0answers
107 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
votes
1answer
170 views

Using the command pattern for a sequence of tasks

I have a 'sequence of tasks' to undertake on a zip file. It can be simplified into these steps: Validate that the file is a ZIP file and is valid Unzip the file Validate the contents are as ...
1
vote
0answers
117 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 ...
8
votes
2answers
529 views

What is a good design pattern for generating an Excel (xlsx) file in code?

See my Update at the bottom for more. I occasionally have projects where I have to output some data as an Excel file (xlsx format). The process is usually: User clicks some buttons in my ...
2
votes
1answer
164 views

In MVC design, do I use a base class over an interface?

In web MVC most designs I've seen, (just choosing model layer as an example) the domain problem class, say students, always inherits the superclass "Model." The name is irrelevant, but why do they ...
0
votes
2answers
79 views

Possible design patterns for base function with possible additions

I have various interfaces i have to implement. Let's assume ITypeA, ITypeB. They have following methods: ITypeA Connect Disconnect GetData SetData ClearData ITypeB Connect Disconnect ...
1
vote
2answers
144 views

How to let the outside world decorate my private field?

Imagine a simple Controller (as in process control) interface. I have some concrete classes, say PIDController, that implement it. I also have some decorator classes that extend these classes ...
3
votes
1answer
188 views

Redundancy caused by polymorphism

I have two chat rooms, one has administration behaviour, and one doesn't. I have factored out all of the common code into a base chat room, but the AdministerChatroom behaviour I have pulled out into ...
3
votes
2answers
512 views

What are the disadvantages of a “simple factory”?

I am reading the book »Head First Design Patterns« from O'Reilly. Before explaining the Factory Method Pattern, they introduce a Simple Factory first. They are using the example of a pizzeria. In a ...
0
votes
1answer
304 views

Does this function do one thing only?

Is the following method considered to be doing one thing only? I'm wondering about that since it takes an optional argument. public function findErrors($name = null) { if ($name) { ...
0
votes
0answers
56 views

Pitfalls of combining dependant traits and exceptions in same file as interface in php

What are the potential pitfalls of combining related class like objects (interfaces, traits, custom exceptions) in the same source file? For code reuse and only loading what I need I always separate ...
1
vote
2answers
101 views

Are there any downsides to replacing js confirm boxes with “mark record as deleted”?

I believe in the user experience of always having a confirm pop-up for deletions. However (though we're very used to it), a separate small pop-up window is not ideal and for users on different ...
0
votes
1answer
139 views

The ViewController design in iOS vs MVC in tradiational web apps design

As I came from the background of webapps and move to iOS programming, I am wondering why we can't just apply the MVC design approach to native apps, i.e. in iOS, the view and controller are tightly ...
1
vote
0answers
165 views

Why should ViewModel route actions to Controller when using the MVCVM pattern?

When reading examples across the Internet (including the MSDN reference) I have found that code examples are all doing the following type of thing: public class FooViewModel : BaseViewModel { ...
4
votes
5answers
438 views

Questioning one of the arguments for dependency injection: Why is creating an object graph hard?

Dependency injection frameworks like Google Guice give the following motivation for their usage (source): To construct an object, you first build its dependencies. But to build each dependency, ...