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

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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
147 views

Is there a programming pattern, design pattern, or naming convention for moving data between related schemas? [on hold]

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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1answer
59 views

Pass Event between Systems in a multi-threaded Entity-Component-System [closed]

To clearify my question: Is there a way to pass Events between Systems in a multi-threaded Entity-Component-System? Original Post: I've read a german article about the Entity-Component-System ...
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1answer
934 views

Design Pattern for Data Validation

What would be the best design pattern for this problem: I have an Object A. Object A can either be registered or deleted from the database depending on the user request. Data validation is performed ...
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4answers
307 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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2answers
271 views

When should something be a class? And are my chosen classes good OO design?

My background: I am new to programming. Python is my only programming knowledge. I program as a hobby, and I'm teaching myself by reading copious amounts of books. I understand enough about OOP to ...
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1answer
96 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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1answer
127 views

How a real MVC is different from todays MVC used in the web? [on hold]

ive heard that MVC used now in days could be called webMVC because they dont implement it like the actual MVC is, so it makes me wonder if there is a guide where i can find the real MVC architecture ...
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2answers
68 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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2answers
202 views

DTO - service layer - statelessness best practices interfering with each other

I am designing a REST API coupled with a service layer that takes DTOs as input and produces them as output. This works fine for most service calls where the DTO is used to access an underlying ...
0
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1answer
67 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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0answers
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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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Abstract factory for web crawler [closed]

Here is my design for an abstract factory for web crawler. I have few web site that i want to crawl. Each site have different page version in each version of page , they will have the same product ...
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2answers
109 views

API - How to handle scope based functionality?

TLDR; Where and possibly how should I implement scope based logic in the example code? I have got a ASP.NET Web Api. The Api uses OData (on top off REST) for data endpoints and OAuth 2.0 ...
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1answer
73 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 ...
3
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2answers
260 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
234 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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6answers
4k views

LSP vs OCP / Liskov Substitution VS Open Close

I am trying to understand the SOLID principles of OOP and I've come to the conclusion that LSP and OCP have some similarities (if not to say more). the open/closed principle states "software ...
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0answers
72 views

What do you think about code reuse? [closed]

I never do/did everything from scratch. When I'm starting a project, I'm always summarizing the problems and searching for other's people solutions. Do you want a authorization, authentication? ...
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2answers
118 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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1answer
154 views

How to design a scriptable communication emulator?

Requirement: We need a tool that simulates a hardware device that communicates via RS232 or TCP/IP to allow us to test our main application which will communicate with the device. Current flow: ...
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1answer
246 views

State Pattern - should a state know about its context?

I am referring to the state pattern as described in this link. In the example class diagram, a context has numerous states. However, it does not show how does a state communicates with a context ...
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1answer
919 views

Useful design patterns for working with FragmentManager on Android

When working with fragments, I have been using a class composed of static methods that define actions on fragments. For any given project, I might have a class called FragmentActions, which contains ...
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2answers
169 views

Best approach for tracking dependent state

Let's pretend I work on a project tracking application. The application is a database backed, server hosted, web application. In this application there are Projects which have many Activities which ...
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63 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
455 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
115 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
101 views

Where and how to reference composite MVP components?

I am learning about the MVP (Model-View-Presenter) Passive View flavour of MVC. I intend to expose events from view interfaces rather than using the observer pattern to remove explicit coupling with ...
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1answer
81 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 ...
7
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1answer
218 views

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
421 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 ...
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4answers
243 views

Relative encapsulation design

Let's say I am doing a 2D application with the following design: There is the Level object that manages the world, and there are world objects which are entities inside the Level object. A world ...
4
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5answers
1k views

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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2answers
126 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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1answer
260 views

Interface questions for using Command Pattern and Dependency Injection together

I have many projects that have essentially the same high level requirement: test all hardware on a device. Each device can have a different communication protocol, requires different test equipment to ...
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3answers
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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 ...
2
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1answer
86 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
574 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
108 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
99 views

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 ...
2
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1answer
41 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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1answer
111 views

PHP - Repository matrix pattern?

I'm trying really hard to refactor some of my legacy code in the project using best practices and design patterns + DDD so I'd love some feedback on an issue I'm currently having. Let's assume that I ...
6
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4answers
694 views

Acceptable placement of the composition root using dependency injection and inversion of control containers

I've read in several sources including Mark Seemann's 'Ploeh' blog about how the appropriate placement of the composition root of an IoC container is as close as possible to the entry point of an ...
4
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1answer
78 views

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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10answers
10k views

How accurate is “Business logic should be in a service, not in a model”?

Situation Earlier this evening I gave an answer to a question on StackOverflow. The question: Editing of an existing object should be done in repository layer or in service? For example ...
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2answers
264 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
124 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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5answers
342 views

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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0answers
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Client side web application architecture - best practice & patterns [duplicate]

I'm inheriting some code that takes a rather different approach to architecture than I'd have chosen myself. It consists of a HTML page, some javascript library imports and a single DIV tag. This ...