Tagged Questions

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

learn more… | top users | synonyms (1)

1
vote
0answers
109 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
487 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 ...
1
vote
1answer
156 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
78 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
143 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
186 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
439 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
303 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
48 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
98 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
115 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
153 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
416 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, ...
3
votes
1answer
105 views

Augmenting functionality of subclasses without code duplication in C++

I have to add common functionality to some classes that share the same superclass, preferably without bloating the superclass. The simplified inheritance chain looks like this: Element -> ...
2
votes
1answer
91 views

Finding a way to simplify complex queries on legacy application

I am working with an existing application built on Rails 3.1/MySql with much of the work taking place in a JavaScript interface, although the actual platforms are not tremendously relevant here, ...
2
votes
1answer
110 views

Is there a pattern or best practice for passing a reference type to multiple classes vs a static class?

My .NET application creates HTML files, and as such, the structure looks like variable myData BuildHomePage() variable graph = new BuildGraphPage(myData) variable table = BuildTablePage(myData) ...
3
votes
1answer
184 views

Project structure: where to put business logic

First of all, I'm not asking where does business logic belong. This has been asked before and most answers I've read agree in that it belongs in the model: Where to put business logic in MVC design? ...
6
votes
2answers
205 views

Is this a valid implementation of the repository pattern?

I've been reading up about the repository pattern, with a view to implementing it in my own application. Almost all examples I've found on the internet use some kind of existing framework rather than ...
0
votes
3answers
150 views

How to change the state of a singleton in runtime

Consider I am going to write a simple file based logger AppLogger to be used in my apps, ideally it should be a singleton so I can call it via public class AppLogger { public static String file = ...
0
votes
1answer
156 views

Should I limit my type name suffix vocabulary when using OOP?

My co-workers tend to think that it is better to limit non-domain type suffixes to a small fixed set of OOP-pattern inspired words, e.g.: *Service *Repository *Factory *Manager *Provider I believe ...
1
vote
1answer
175 views

Design for object with optional and modifiable attributtes?

I've been using the Builder pattern to create objects with a large number of attributes, where most of them are optional. But up until now, I've defined them as final, as recommended by Joshua Block ...
9
votes
4answers
456 views

Are first-class functions a substitute for the Strategy pattern?

The Strategy design pattern is often regarded as a substitute for first-class functions in languages that lack them. So for example say you wanted to pass functionality into an object. In Java you'd ...
0
votes
3answers
185 views

Drawback of using static method [duplicate]

For methods that never access instance variable or static variable and they act just like a function (name-spaced) and they are deterministic base on only the input arguments , I want to ask, are ...
4
votes
2answers
364 views

How to layer if statements when order of logic is irrelevant?

Basically I have a series of logic in my website that can lead to 5 total outcomes. Basically two different if tests and then a catch all else statement. For example: if cond1: if mod1: ...
0
votes
1answer
151 views

Best Practices For Temporary Scripts (Python)

I am running two separate programs which are similar enough that they share a lot of code. I run these programs often and after I evaluate the output. This is a very fluid process and everytime is ...
1
vote
0answers
63 views

Dealing with class optional dependencies

I am wondering how are you guys handling an optional class properties. Let's say I have a product that can bud doesn't have to have a color property. Is that really the best way of doing that? Should ...
4
votes
1answer
103 views

JS design pattern/algorithm for avoiding duplicate redraws in a fairly coupled system

Given: some sort of widget based web app lots of JS functionality high coupling (communication/callbacks between widgets) widgets draw themselves certain widgets need to do a complete and fairly ...
1
vote
2answers
159 views

Limitations of the Identity Map pattern

After asking about the implementation in Ruby of the Identity Map pattern because the potential memory leak in long running server apps, I am considering my initial concept of that pattern. Initially ...
2
votes
1answer
198 views

Poltergeist and factories [closed]

I've just come across the Poltergeist anti-pattern - and maybe it's because the morning coffee hasn't kicked in yet, but I read the description: a poltergeist (or gypsy wagon) is a short-lived, ...
0
votes
1answer
126 views

How to generalize a classes that has identical function plus some additional function

I have some designing problems with my project. To illustrate my problem, I'll use the following two classes from my project. public class RAM_UserManagement{ private Map<int,User> userList; ...
1
vote
2answers
202 views

How do you guard against hidden overflows

consider the following: (i+j)/2 i and j are both 32 bit integers and the result should also be. But in the little equation, there's a hidden overflow, i+j could become larger then a 32 bit integer ...
0
votes
2answers
148 views

Which pattern is suitable to send multiple type of responses through REST web service?

I have bunch of REST style web services which support XML and JSON type responses. Now I have to modify existing web services such that they provide Protobuf type of responses. Developer who has ...
0
votes
1answer
176 views

Design Pattern: A single class with multiple purposes, or multiple extended classes each with their own purpose in PHP

I'm working on a PHP framework called Carbon CMS. This framework will be used as base to build larger web applications on top of it. This framework should provide all kinds of interfaces such as ...
1
vote
1answer
188 views

I'm always reimplementing observer/subject code in Java. Is there a better option?

I'm always writing observer/subject interfaces in a particular Java project, e.g.: /** * Registers the receiver to the dispatcher. * When data arrives that the receiver can process, * it will be ...
1
vote
3answers
165 views

Protected variable & protected method in the era of TDD [closed]

I understand protected method is good for unit testing since you can easily mock by the class by overriding the protected method for the sake of testing. However, protected variable is just a global ...
0
votes
1answer
55 views

Pattern or idea to communicate with async hardware

This is more like a theory question than a practical one. And although I am using Arduino and Labview, it should work independently of the platform. I have an Arduino board controlling a set of pumps ...
2
votes
3answers
172 views

Structural pattern for an unconventional use of a database

I'm writing a game client as a personal project and using using it as a vehicle to learn about Java database access, specifically Neo4j, and possibly Spring Data Neo4j if I decide it's appropriate. ...
0
votes
2answers
417 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 ...
2
votes
3answers
178 views

How to use Option Type Pattern in a language that doesn't support generics?

I've been interested to start using the Null Object / Option Type approach for replacing my old habits of null-checking multiple parts of my code. But, from the many examples I saw out there, it seems ...
0
votes
1answer
71 views

Factory Design pattern in languages with class types

I was reading in Peter Norvig's Design Patterns presentation. From slide 13: Dynamic version needs only the Window classes. The classes themselves serve as factories This works because ...
1
vote
3answers
190 views

Extending a struct. Using helper classes rather than composition

I have a struct which I want to add static methods to. Yes, you guessed right I'm talking about Datetime. It's a pretty typical requirement to add MyCustomParse. It happens to return Datetime?, so ...
0
votes
2answers
135 views

Confused about javascript module pattern implementation

I have a class written on a project I'm working on that I've been told is using the module pattern, but it's doing things a little differently than the examples I've seen. It basically takes this ...
0
votes
3answers
420 views

Eliminate duplicate code in nested IFs without creating a function [duplicate]

Let's say we have two ifs that depend on each other: if var exists { if var is array { //Do stuff with var } else { //Resolve the problem } } else { //Resolve the ...
4
votes
2answers
877 views

How to replace inheritance with composition in this case?

I've recently read several articles about the advantages of the composition over inheritance. Their authors said that you can always replace inheritance with composition (to be precise, they say they ...
0
votes
1answer
152 views

Is this a specific pattern and what is its purpose? [closed]

I recently stumbled over the following C++ Code which confused me a bit: class One {/*definition*/}; template<class Base > class Two : public Base {/*definition*/}; template<class Base > ...
1
vote
0answers
118 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 ...
0
votes
0answers
48 views

Extending database model of ORM in subproject

I have a maven project which contains some entities which are stored in a database. The purpose of this project is to manage personal information, users, locations, etc. This project can work on its ...
1
vote
1answer
116 views

Clarification about MVC Design pattern

I've been reading up on MVC and I had a doubt. The example where the Model, View and Controller are all individual classes whose objects are created and used to deploy the application in another ...
0
votes
0answers
92 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. ...
0
votes
0answers
52 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 ...