Questions tagged [design-patterns]

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

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Designing controller for modular Java architecture

We are designing a system which mimics a BPEL application with sets of functional requirements such as bulk messaging, managing SLAs, error handling and so on. One of the intentions is to modularize ...
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4answers
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Is it a "pattern smell" to put getters like "FullName" or "FormattedPhoneNumber" in your model?

I'm working on an ASP.NET MVC app, and I've been getting into the habit of putting what seem like helpful and convenient getters into my model/entity classes. For example: public class Member { ...
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2answers
491 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 ...
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3answers
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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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3answers
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Design Anti-Patterns - C# - Do you call this a God object?

I am writing Portfolio module for my web site and it has 3 components. Gallery Category, Gallery, & Gallery Images. I am doing all the request handling, (creating, reading, updating, other), for ...
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9answers
8k views

Design Patterns: Should I learn them? [closed]

So it's kinda weird asking two questions back-to-back, but they aren't very related and I didn't want to combine them, but I'm not spamming questions, I promise! Anyway, I'm a recent college grad, ...
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1answer
7k views

Permissions/right model/pattern for .NET application

I need to implement flexible AND simple (if such thing exist) and at the same time utilize built-on means if possible So far I have MembershipProvider and RoleProviders implemented. This is cool but ...
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4answers
2k views

Should strategy objects have state?

I have an application object that needs to validate some data. The particular validation algorithm isn't known until runtime, so I pass a validation object to it, using the strategy pattern. The ...
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2answers
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Iterative alternative to decorators?

So decorators wrap a base class recursively, right? And have a single super class object which is at the "core" class. Couldn't you just add an ArryList/LinkedList of decorations in the "core" class ...
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2answers
6k views

What are the main practices and design patterns every .NET guy should know? [closed]

In my brief time as a professional programmer I've seen lots of applications written by programmers who's entire education appears to have been reading the first couple of chapters in a .NET 2.0 book. ...
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4answers
766 views

What "code smells" are there that are a symptom that an event listener model is required?

What are the symptoms in a code base that indicate that an event-listener approach is required? It seems to me that when there are classes that need to be called by multiple, not defined at design-...
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1answer
5k views

Python programming patterns and practices? [closed]

What are the best python programming patterns and practices you are using every day? I don't mean only design patterns (there are lot of OO design patterns that can be used in python), I mean pure ...
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5answers
634 views

Anti patterns - Worth spending time or not

I have read this question and after a very long time it's clear I still don't understand anti-patterns. perhaps, it raised a new level of curosity to know why should I read Anti design pattern if they ...
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2answers
3k views

Data Access Layer, Business Class or Repository?

I've been having a debate within my team on what constitutes a Data Access Layer vs Data Functions vs Business Layers. My thoughts is all database access is done in a data access layer with ...
2
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2answers
726 views

Delegate pattern for retrieving data v.s. using simple setters

I am considering using the Delegate Pattern to get some data necessary for an operation. There are a few different pieces of data that the algorithm needs to run, but they all have default values that ...
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3answers
2k views

Architectural Patterns for a Game

So I've got a solution that contains a few big projects, which I'm trying to break down into smaller projects with more isolated responsibilities. This is a game I'm tinkering with -- I'm mainly a LOB ...
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2answers
2k views

Anemic Domain Model, Business Logic and DataMapper (PHP)

I've implemented a rudimentary ORM layer based on DataMapper (I don't want to use a full blown ORM like Propel/Doctrine - for anything beyond simple fetch/save ops I prefer to access the data directly ...
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3answers
385 views

What design would you propose to log reporting data so that the capture of, say, an additional form field can implemented easier?

Why is there an emphasis to log reporting information through an application to a separate database? I have seen designs where a logging manager is available to every business layer class whether it ...
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1answer
2k views

Delegate Pattern : Delegate or Delegator?

I've a simple question about the terminology used in the Delegate pattern; Let's say I create an object that will be responsible to download something from the Net and when it is finished, will call ...
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8answers
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How do "You Ain't Gonna Need it" and "Now is better than never" play together?

I often find myself embracing "now is better than never" when I'm advancing the DRYness of a design. Typically, I find that I need to cultivate an understanding of the One Authoritative Location for ...
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3answers
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Using CSS classes as decorators - a good pattern?

I've been building a web-app with a fairly complex GUI - many small elements alongside eachother and within other elements that need various behaviours (dragging, clicking, but context-sensitive). My ...
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16answers
78k views

What is the most frequently used design pattern? [closed]

Which design pattern do you think is the most popular?
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1answer
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Is it common/correct using MVVM to expect multiple views and corresponding view-models for a particular model?

Consider a somewhat contrived model that goes something like: class Player { public int Health; public int Ammo; public Weapon CurrentWeapon; public PhysicalState State { ...
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4answers
4k views

When designing an application around Model-View-Controller (MVC), what is in your toolbox?

There are a lot of great explanations for what the Model-View-Controller design pattern is, but I am having trouble finding good resources showing how to use it in practice. So, when you are starting ...
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2answers
276 views

Delegate pattern : Who has the responsability to create return Object?

I've a question about the Delegate Pattern : If I want to delegate the parsing of a xml file, for instance, that I want to be converted into a Key-value Dictionary. Let's take this classical example....
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3answers
5k views

How to figure out real life examples of design patterns?

Hi I am learning design patterns from a book . How to figure out the actual production code where it is implemented . For example , if I am learning strategy pattern , it might be implemented ...
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1answer
7k views

Software architecture for authentication/access-control of REST web service

I am setting up a new RESTful web service and I need to provide a role-based access control model. I need to create an architecture that will allow users to provide their username and password to get ...
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3answers
387 views

How do you organize a large data layer in a project?

I have a data layer that strictly interacts with the database and returns the result into a model. I have an asynchronous connection with the DB so sometimes I have to chain results where I have to ...
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2answers
649 views

"Don't cross the streams" Database access objects independant of the Data tier in an N-Tier architecture?

I'm adding functionality to our website which performs long-running processes asynchronously using MSMQ. Doing this ansynch, however means we need to notify users when their requests are completed. ...
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1answer
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Building a table (DataGridView) while keeping decoupled from Model

I'll try to keep this simple. Small C# app, dialog based, one has a DataGridView. I've got an UpdateTable function in the form that accepts a DataSet and passes it to the DataGridView.DataSource. &...
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9answers
3k views

How should you explain Design Patterns to people outside of Software World

I want to explain design patterns to my niece, but always struggle in doing so. It is largely due to my lack of clear understanding of design patterns. How do you suggest explaining patterns like MVC,...
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1answer
443 views

Model-view-presenters and user-interactions involving separate dialogs

I have a UI form written using model-view-presenter that has, among other things, a listbox containing a number of different domain objects. The form also contains an add/update button which pulls up ...
10
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2answers
794 views

Which GOF design patterns are already implemented as first-class language features in C#?

(This question was closed on Stack Overflow due to being "too broad" and "not a real question" so maybe it's more appropriate here?) Inspired by this question. We know events are a language-level ...
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1answer
873 views

When is a glue or management class doing too much?

I'm prone to building centralized classes that manage the other classes in my designs. It doesn't store everything itself, but most data requests would go to the "manager" first. While looking at an ...
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8answers
371 views

Identifying which pattern fits better

I'm developing a software to program a device. I have some commands like Reset, Read_Version, Read_memory, Write_memory, Erase_memory. Reset and Read_Version are fixed. They don't need parameters. ...
5
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4answers
3k views

How to learn the practical uses of design patterns

I use OOP programming with inheritance, but I've not yet used interfaces.I want to learn how to use design patterns, but I'm finding them very difficult to learn. Is there is any way to learn design ...
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5answers
848 views

Ways of handling asynchronous receive calls

I am implementing a primitive message-passing system. Currently, I am designing a receive function for async calls. Can I implement such a async receive function without using callback functions?
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2answers
1k views

What are the best patterns/designs for stateful API development?

I am about to implement a API for my TCP/IP server written in Java. Right now I have a temporary method that takes a String, executes a command based on the String and returns a String basically like ...
1
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5answers
473 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; }
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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 ...
9
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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 ...
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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 ...
9
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6answers
599 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 ...
43
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6answers
24k 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 ...
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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 ...
5
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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 ...
2
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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 ...
3
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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 ...
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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 ...
5
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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. ...