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

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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 ...
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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 ...
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222 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 ...
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3answers
668 views

MVC is a GUI Architecture or a Architecture to GUI and Domain?

Fowler refers to the MVC, as a GUI architecture: There have been many different ways to organize the code for a rich client system. Here I discuss a selection of those that I feel have been the ...
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What should a domain object's validation cover?

I'm trying to figure out how to do validation of domain objects that need external resources, such as data mappers/dao Firstly here's my code class User { const INVALID_ID = 1; const ...
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4answers
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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 ...
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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) ...
69
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14answers
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What should take precedence: YAGNI or Good Design?

At which point should YAGNI take precedence against good coding practices and vice versa? I'm working on a project at work and want to slowly introduce good code standards to my co-workers (currently ...
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1answer
101 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 ...
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3answers
383 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 ...
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3answers
174 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 ...
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4answers
408 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(/) ...
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1answer
134 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 ...
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2answers
83 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 ...
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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 ...
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71 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 & ...
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2answers
357 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 ...
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2answers
239 views

Optimization ended up in casting an object at each method call

I've been doing some optimization for the following piece of code : public void DrawLine(int x1, int y1, int x2, int y2, int color) { _bitmap.DrawLineBresenham(x1, y1, x2, y2, color); } After ...
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129 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 ...
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84 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 ...
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2answers
484 views

Correct way to inject dependencies in Business logic service?

Currently the structure of my application is as below Web App --> WCF Service (just a facade) --> Business Logic Services --> Repository -> Entity Framework Datacontext Now each of my Business logic ...
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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 ...
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1answer
96 views

RESTful composition/inclusion of other resources

I have a few HTTP resources, and i'm wondering if including the models of one in the other is acceptable or if there is a cleaner method. In this example, we have a ton of "news" resources, and users ...
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1answer
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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 ...
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2answers
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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 ...
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5answers
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Are design patterns independent of programming languages?

I have been recently working on Objective C and came across use of Delegate pattern. I had seen most of the common patterns theoretically in Java, thanks to the Head First book. But at times looking ...
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135 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 ...
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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 ...
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445 views

Is there a standard, formal name for an object or class that behaves as if it is a given object?

I have an app in Django that expects to get a record with the fields email, first_name, and last_name. However, sometimes I want to be able to send it something that isn't actually a record but ...
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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 ...
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1answer
616 views

Trying to understand 3 layer programming [closed]

I am confused to understand the structure of a 3 layer programm. Where is good place for exceptions, entity and etc.? If I use MVC, in my UI model, how to transfer entity class to model class and ...
0
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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, ...
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2answers
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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 ...
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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 ...
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Mapping multiple differing taxonomies to each other

At work we have a varied number of websites selling second-hand products. The bosses have noticed that there's often some overlap between the products sold on some of the websites and would like to ...
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287 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 ...
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1answer
154 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 ...
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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 ...
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2answers
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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 ...
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102 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
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1answer
167 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 ...
3
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3answers
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What is the middleware pattern?

Here's a Ruby poject that implements the middleware pattern. From the description, I have no idea what the pattern is, what it's useful for, and why other solutions wouldn't work as well. What is ...
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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 ...
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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 ...
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957 views

A sample Memento pattern: Is it correct?

Following this query on memento pattern, I have tried to put my understanding to test. Memento pattern stands for three things: Saving state of the "memento" object for its successful ...
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2answers
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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 ...
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2answers
572 views

What is the proper name for this design pattern in Python? [closed]

In Python, is the proper name for the PersonXXX class below PersonProxy, PersonInterface, etc? import rest class PersonXXX(object): def __init__(self,db_url): self.resource = ...
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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 ...
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3answers
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Writing your own framework or using an existing one? [duplicate]

I know there are similar questions to this one, and I've read most of them. Most of the answers to these questions are talking about "cost-effectiveness" and "time-saving" aspects of the frameworks, ...
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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 ...