design-patterns

Validity of GUI design patterns under linux

I am investigating a switch from windows to linux and i struggle to find samples of design patterns applied in this world. The application is a classic client server with detailed forms for each business entity. It will be taking user input, do some validation checks, a few calculations, and save them to database. It will also have list...

Structuring iPhone/iPad application views

I have an idea about an application that I want to build and Im new to iPhone/iPad development (but not new to development in other languages/frameworks such as .NET and Java). I want to layout some views on the screen so that they animate (slide in) from different directions into their places. The question is about the strucuture of th...

design an extendable database model

Hi! Currently I'm doing a project whose specifications are unclear - well who doesn't. I wonder what's the best development strategy to design a DB, that's going to be extended sooner or later with additional tables and relations. I want to include "changeability". My main concern is that I want to apply design patterns (it's a univer...

How to structure an application written in a functional language?

How is code commonly organized in FP applications? Along what lines do you separate files, modules, directories, etc.? ...

Seperation of game- and rendering logic

What is the best way to seperate rendering code from the actually game engine/logic code? And is it even a good idea to seperate those? Let's assume we have a game object called Knight. The Knight has to be rendered on the screen for the user to see. We're now left with two choices. Either we give the Knight a Render/Draw method that we...

singleton vs factory?

i've got 3 Log classes that all implements iLog interface: DatabaseLog FileLog ScreenLog there can only be one instance of them. initially i though of using single pattern for each class but then i thought why not use a factory for instantiation instead, cause then i wont have to create single pattern for each one of them and for all ...

DRY programming dilemma

the situation is like this: im creating a Logger class that can write to a file but the write_to_file() function is in a helper class as a static function. i could call that function but then the Log class would be dependent to the helper class. isn't dependency bad? but if i can let it use a helper function then what is the point of...

How can I make a family of singletons?

I want to create a set of classes that share a lot of common behavior. Of course in OOP when you think that you automatically think "abstract class with subclasses". But among the things I want these classes to do is to each have a static list of instances of the class. The list should function as sort of a singleton within the class. I ...

Has anyone ever encountered a Monad Transformer in the wild?

In my area of business - back office IT for a financial institution - it is very common for a software component to carry a global configuration around, to log it's progress, to have some kind of error handling / computation short circuit... Things that can be modelled nicely by Reader-, Writer-, Maybe-monads and the like in Haskell and ...

Is there a design pattern for this ?

I have a component that needs to call a specific service depending on the input it receives. So my component has to look at the input and based on a configuration that says "for this input call this service with this data" needs to call the proper service. The services have a common signature method and a specific one (each). I thought ...

Are there any performance or contention considerations when using VB.Net "Shared" or C# "static" classes and methods?

I have a C# class library behind a WCF service. The library contains ClassA which is declared as static. This static class has a method MethodA which accepts a string and uses LINQ to query the database for a translation of the string which it then sends back through the webservice to the client. My question is whether using a s...

JFace Providers and MVC/MVP/etc.

Where do the JFace providers belong in an MVP or MVC architecture? Or should Provider pattern be treated as a different way of View-Model separation? If so, is it the same as the ASP.NET Provider pattern? Is there an article on a proper design of JFace applications using Providers? ...

The Purpose of a Service Layer and ASP.NET MVC 2

In an effort to understand MVC 2 and attempt to get my company to adopt it as a viable platform for future development, I have been doing a lot of reading lately. Having worked with ASP.NET pretty exclusively for the past few years, I had some catching up to do. Currently, I understand the repository pattern, models, controllers, data ...

Silverlight Async Design Pattern Issue

I'm in the middle of a Silverlight application and I have a function which needs to call a webservice and using the result complete the rest of the function. My issue is that I would have normally done a synchronous web service call got the result and using that carried on with the function. As Silverlight doesn't support synchronous w...

Can the Singleton be replaced by Factory?

Hello Everyone There are already quite some posts about the Singleton-Pattern around, but I would like to start another one on this topic since I would like to know if the Factory-Pattern would be the right approach to remove this "anti-pattern". In the past I used the singleton quite a lot, also did my fellow collegues since it is so ...

Stateless singleton VS Static methods

Hey, Don't find any good answer to this simple question about helper/utils classes: Why would i create a singleton (stateless) rather than static methods? Why an object instance could be needed while the object has no state? Sometimes i really don't know what to use... ...

Design patterns, how do they differ from other programming styles?

Design patterns aren't necessarily a programming style but rather a template for solving a problem in a number of different situations. But how do they differ from other programming styles? Thanks Edit: "(a) What are design patterns? How do these differ from other programming styles? [7]" ...

What elegant method callback design should be used ?

Hi, I'm surprised this question wasn't asked before on SO (well, at least I couldn't find it). Have you ever designed a method-callback pattern (something like a "pointer" to a class method) in C++ and, if so, how did you do it ? I know a method is just a regular function with some hidden this parameter to serve as a context and I hav...

Is Domain Anaemia appropriate in a Service Oriented Architecture?

I want to be clear on this. When I say domain anaemia, I mean intentional domain anaemia, not accidental. In a world where most of our business logic is hidden away behind a bunch of services, is a full domain model really necessary? This is the question I've had to ask myself recently since working on a project where the "domain" mod...

Using inheritance and polymorphism to solve a common game problem

I have two classes; let's call them Ogre and Wizard. (All fields are public to make the example easier to type in.) public class Ogre { int weight; int height; int axeLength; } public class Wizard { int age; int IQ; int height; } In each class I can create a method called, say, battle() that will determine who will win if...