Questions tagged [design-patterns]

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

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28
votes
12answers
19k views

What design patterns are the worst or most narrowly defined? [closed]

For every programming project, managers with past programming experience try to shine when they recommend some design patterns for your project. I like design patterns when they make sense or if you ...
8
votes
4answers
2k views

Modular Architecture for Processing Pipeline

I am trying to design the architecture of a system that I will be implementing in C++, and I was wondering if people could think of a good approach, or critique the approach that I have designed so ...
14
votes
3answers
11k views

How do I set up MVP for a Winforms solution?

I have used MVP and MVC in the past, and I prefer MVP as it controls the flow of execution so much better in my opinion. I have created my infrastructure (datastore/repository classes) and use them ...
1
vote
5answers
464 views

Does this have a name? DRY overloading?

public int foo(int x) { int defaultValue = 0; return foo(x, defaultValue); } public int foo(int x, int y) { return x + y; }
8
votes
1answer
3k views

How best to design Access Control Layer in n-tier architecture application

This is a typical architecture scenario for a 3-tier design: UI-tier Has Graphical User Interface components Middle-tier Has business logic including the following layers: Data Access Layer (DAL) ...
16
votes
3answers
7k views

Recommended order for learning design patterns? [closed]

I can't help but notice the amount of design patterns that are out there. Does anyone have suggestions on an order I should learn them in? Or should I pick and choose them at random? The only one I ...
2
votes
3answers
1k views

Design Patterns in Delphi [closed]

Delphi has a few problems implementing some design patterns because some features it lacks, like multiple inheritance and no pure abstract classes. Are there any good resources or "Adaptation-...
12
votes
5answers
2k views

Do you leverage the benefits of the open-closed principle?

The open-closed principle (OCP) states that an object should be open for extension but closed for modification. I believe I understand it and use it in conjunction with SRP to create classes that do ...
8
votes
6answers
2k views

Better Understand the 'Strategy' Design Pattern

I have been interested in design patterns for a while and started reading "Head First Design Patterns". I started with the first pattern called the 'Strategy' pattern. I went through the problem ...
9
votes
6answers
588 views

Giving a presentation on “code style and design patterns” [closed]

My company (small, about 40 people across 3 offices) occasionally does "developer workshops" online where one of the devs hosts a presentation about some tech topic. It's not necessarily about our ...
591
votes
13answers
249k views

So Singletons are bad, then what?

There has been a lot of discussion lately about the problems with using (and overusing) Singletons. I've been one of those people earlier in my career too. I can see what the problem is now, and yet, ...
2
votes
6answers
2k views

Is “call and return” a pattern or an antipattern?

Imagine to have this code: class Foo: def __init__(self, active): self.active = active def doAction(self): if not self.active: return # do something f=Foo(false) f.doAction() ...
5
votes
4answers
6k views

Why GRASP patterns are less known than GOF ones?

Design patterns help developers to improve the quality of their design, but only GOF patterns are very known, and paterns like GRASP that gives a good concepts like Information Expert,low coupling and ...
9
votes
3answers
3k views

Design pattern for window management in a Java Swing app

I've just started creating my very first little Java Swing app. When the program opens, it brings up a single, simple window with a label and a couple buttons. Clicking one of those buttons is ...
5
votes
4answers
317 views

How should I evaluate a training class? [closed]

My company is giving us the possibility to sign up for some offsite training classes on Design Patterns. Browsing through the brochures, I'm already feeling bored (and somewhat repelled by the ...
26
votes
7answers
3k views

The Singleton Pattern [duplicate]

Possible Duplicate: When is Singleton appropriate? I am a new programmer (4 months into my first job) and have recently taken an interest in design patterns. One that I have used recently is the ...
2
votes
3answers
1k views

Multithreaded UI desktop application issues

I am involved into development a rich UI project: desktop windows application. Application uses asynchronous invocations and in its turn it should be ready to process external messages (events). The ...
7
votes
1answer
655 views

Can Test-Driven development work in legacy projects?

So here is a question for you, having read some great answers to questions such as Test-Driven Development - Convince Me. So my question is: "Can Test-Driven Development be used effectively on non-...
30
votes
5answers
30k views

What is the difference between all-static-methods and applying a singleton pattern? [duplicate]

I am making a database to store information about the users of my website (I am using stuts2 and hence Java EE technology). For the database I'll be making a DBManager. Should I apply singleton ...
3
votes
2answers
728 views

Is is common to use the command pattern for property get/sets?

Suppose I have a controller class with a bunch of properties. Each time a property is changed, I would like to update the model. Now also suppose that I use the command pattern to perform model ...
6
votes
1answer
347 views

Need to re-build an application - how?

For our main system, we have a small monitor application that sits outside our network and periodically tries to log in to verify the system still works. We have a problem with the monitor though in ...
6
votes
2answers
1k views

How to program for constraints/rules

First the background, during interviews in the past, many times I have been asked to design some or other variation of card game as programming puzzle, and I have tried to design it in OO way, but I ...
10
votes
2answers
3k views

design pattern for unit testing? [duplicate]

I am beginner in developing test cases, and want to follow good patterns for developing test cases rather than following some person or company's specific ideas. Some people don't make test cases and ...
2
votes
1answer
432 views

PHP objects with configurable data interfaces

I have a User class which needs to load data from a variety of sources, e.g. the main user database, WordPress user metadata, authorizations from another app, etc. For the sake of organization, I want ...
8
votes
2answers
1k views

Do Ruby (and other dynamic language) programmers use IoC / Dependency Injection?

I'm primarily an ASP.NET developer and the single thing i've been introduced to in recent years that has had the most dramatic impact on the quality of the code I write has learning how to use IoC ...
3
votes
3answers
83 views

How to manage tailored/branded web tools?

We produce a number of analysis tools which we re-brand and customise for other businesses to include in their websites. The tools are typically product comparison, data/trend analysis and report ...
11
votes
4answers
2k views

Refactoring in domain driven design [closed]

I've just started working on a project and we're using domain-driven design (as defined by Eric Evans in Domain-Driven Design: Tackling Complexity in the Heart of Software. I believe that our project ...
13
votes
8answers
3k views

Best way to model a singleton in a relational database

When designing relational database schema for web applications, I often find a case where I end up creating a table just to contain one row, and only one row. It feels like that is the wrong way to ...
42
votes
6answers
22k views

How much business logic should be allowed to exist in the controller layer?

Sometimes we have some business logic represented in the controller code of our applications. This is usually logic that differentiates what methods to call from the model and/or what arguments to ...
5
votes
1answer
327 views

MVC for our application?

There are some issues about how to manage our program designs and programming styles. I was assigned to find a solution to write reusable code - though, the programming team does not follow the rules. ...
5
votes
2answers
552 views

ORM domain design pitfalls

Are there any patterns which seem sensible when designing an object oriented domain, but do not translate nicely onto a relational database schema? If so, are there standard patterns that can be used ...
32
votes
7answers
3k views

Design Patterns for Javascript [duplicate]

A lot of web frameworks have a MVC-style layout to code and approaching problems. What are some good similar paradigms for JavaScript? I'm already using a framework (jQuery) and unobtrusive js, but ...
7
votes
2answers
303 views

Do you experiment with unconventional ways to use design patterns?

We stick to standard usages and best practices because they work and communicate intent well, but without trying new things we can't really grow. Have you ever tried something that seemed absurd but ...
3
votes
4answers
717 views

Which one of the SOLID principles had the largest effect on your code? [closed]

Which if the SOLID principles introduced by "Uncle Bob" Martin had the largest effect on your day to day coding? Please give details!
8
votes
6answers
6k views

Highly scalable and dynamic “rule-based” applications?

For a large enterprise app, everyone knows that being able to adjust to change is one of the most important aspects of design. I use a rule-based approach a lot of the time to deal with changing ...
5
votes
2answers
2k views

Do you know of a data-pump design pattern?

I frequently encounter a situation where I need to write a program which reads data-objects from a file or system, does a transformation on the data, convert the data to another datamodel and then ...
4
votes
2answers
6k views

What are the responsibilities of a Manager and of the Dao Layers

In several projects we have been using the following layers: Action (has 1 or more managers) Manager(has 1 or more Daos) Dao But most of the time the manager only calls the dao. We do use the ...
12
votes
2answers
4k views

Static Create method — pros and cons compared with constructors

What are the pros and cons of having static object creation methods over constructors? class Foo { private Foo(object arg) { } public static Foo Create(object arg) { if (!ValidateParam(arg)) ...
71
votes
5answers
76k views

What are the benefits of using Dependency Injection and IoC Containers?

I'm planning to do a talk on Dependency Injection and IoC Containers, and I'm looking for some good arguments for using it. What are the most important benefits of using this technique, and these ...
3
votes
5answers
806 views

Is this technique a design pattern? If so, what's it called?

I'll use C# as an example, but it should apply globally. Say I have a string value that should be one of a few constants, but I also want the client to set which string value to use so: private int ...
8
votes
2answers
488 views

Design Pattern Books, Papers or Resources for Non-Object Orientated Paradigms?

After viewing this video on InfoQ about functional design patterns I was wondering what resources are out there on design patterns for non-object orientated paradigms. There are plenty out there for ...
7
votes
8answers
17k views

What is a “wrapper” program?

Where I work, employees use a third-party desktop program for their clients. This program saves data to a flat file. My colleague wants to write a Java program that uploads that flat file to a remote ...
8
votes
5answers
484 views

How can we make software development best practices more interesting to people without a software background?

Where I work there are a few experienced software developers with a software background, but the majority of developers are physicists or chemists with excellent domain knowledge but limited ...
4
votes
2answers
10k views

What sort of Design Patterns do you use in Android Development? [closed]

I have been developing on Android for a couple months now, and building upon one in house program I found the scalability to be lacking. I have that gut feeling that if I applied some OO Design ...
1
vote
1answer
311 views

What design pattern is best suitable with this context?

I have a base class Shape, and drived classes Line Segment, Arc, B-spline,... I want to find the intersection point between these shapes. I would like: Shape* a = new LineSegment(); Shape* b = new ...
3
votes
1answer
272 views

Why doesn't DDD consider Documents?

... that is, the inputs and outputs of service functions ? Are entities, or aggregates, allowed to leave service boundaries?
7
votes
3answers
216 views

System Decoupled in the Wrong Places: Meta-Problem? [closed]

At a meta level, I often find that when I grow a codebase organically, parts of the system that I eventually find need to know about each other (at least through some interface) have been mercilessly ...
21
votes
8answers
10k views

Is the GoF book still the one to read? [duplicate]

Possible Duplicate: Is there a canonical book on design patterns? I'd like to read a design patterns book. GoF for sure is the one to read. But after 15 years is it still valid, I mean isn't ...
4
votes
1answer
368 views

Would this be an effective use of the Subject/Observer pattern, or is there a better way?

TBH: I've never used an observer pattern. But it looks pretty useful for this situation: I'm developing a very simple strategy game. It involves two combatants who simultaneously bludgeon each ...
33
votes
11answers
5k views

Are design patterns generally a force for good or bad? [closed]

I've heard it argued that design patterns are the best thing since sliced bread. I've also heard it argued that design patterns tend to exacerbate "Second System Syndrome," that they are massively ...