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Questions tagged [design-patterns]

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

2
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1answer
112 views

Design pattern for an indeterminate number and format of questions

In my application, I have a finite number of question types, but the order in which they're asked and whether they're asked at all is not known up-front. An example analogy is a hotel booking process,...
0
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1answer
84 views

Which is better solution - having separate model class against each REST API or keep adding info in single object?

I have a class Person. Person { String firstName; String lastName; String Date dob; String email; String mobileNumber; String address; } To add a person, I have following REST APIs: POST /...
0
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1answer
57 views

decorator pattern for generating complete html

I am trying to figure out the best way to decorate html. What I mean is replacing specific syntax string with the actual content. Kind of like, razor syntax in Asp.net MVC using <%= %>. ...
0
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2answers
110 views

DDD enforcing business rules

New to DDD I have a simple case a I would like to model using DDD approach 2 entities Student and Course Relevant property for Student are StudentId and Budget Relevant property for Course are ...
1
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3answers
421 views

Pitfalls of Domain-Driven Design with Entity Framework

A lot of tutorials on DDD I studied are mostly covering theory. They all have rudimentary code examples (Pluralsight and similar). On the web there are also attempts by a few people to create ...
1
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1answer
90 views

Problem with business and data access layer design

I am creating a library to interact with third party api.This library will be wrapper around that third party library and i want to expose my wrapper methods to client(webapi,winform,console,mvc etc..)...
0
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1answer
66 views

Java Design for Data enrichment based on logic defined in a database

I have the following requirement. Read data from a messaging Queue and process each message to enrich the message and then finally send the enriched message to a different system. The enrichment ...
0
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5answers
144 views

Data only class, other classes that read/modify it?

I have a class that only holds data, specifically Collections of data, it is called *BezierSplineData: class BezierSplineData { public List<BezierSplineControlPoint> ControlPoints; // ...
0
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1answer
104 views

Onion Architecture - Multiple Apps

Onion Architecture talks about separating the UI, Service, and Data Layers. All the samples usually given for this involve a single deployment model of the application. For example in .net most of the ...
46
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3answers
7k views

Using a “Pass-through (God) Service” is bad, right? [duplicate]

My team has developed a new service layer in our application. They created a bunch of services that implement their interfaces (E.g., ICustomerService, IUserService, etc). That's pretty good so far. ...
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2answers
60 views

Design Pattern to wrap a series of step

I'm already posting this question on StackOverflow, but thought that asking it in different communities might give me different insight. So here's the repost of the question: Hello, I'm having a ...
2
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3answers
109 views

Reconciling MVC with a strategy pattern

I am working on a Rails application which employs a classic MVC as its fundamental structure. In that structure the controller is supposed to be responsible for "which view to render when". Now after ...
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0answers
29 views

What should be the code architecture to download and cache offline data (Images/Videos/3d Models)?

I'm developing an application which has a 3D room. Each room is a 3d model and can contain media boards. each media board contains image(s) as slides or video. I have created following Data Models : ...
1
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2answers
45 views

Pattern or framework for resolving simultaneous inputs

I am tracking the position of characters on a 2D grid (this is a computer game). At every step each character can attempt to move (stationary, up, down, left, or right). There are some rules that ...
0
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1answer
52 views

Using the adapter design pattern for a news application microservice

I am currently developing the backend for a news application, which fetches news from various aggregators (e.g. Feedly). I thought this qualified as a good use case for the adapter design pattern, so ...
0
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1answer
48 views

Pseudo-Factory Abstract Class

So I have a requirement for something like this: The client shouldn't be aware of how the actual classes are implemented or constructed. The classes implement a common interface So I used Factory ...
2
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4answers
132 views

Is Implementation class exposure fine in Dependency Inversion

Basically we should depend on abstractions instead of concrete classes, that's the Dependency Inversion main principle. interface ITest { void DoSomething(); } class TestImpl : ITest { ...
1
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2answers
59 views

Building a plugins-based code in Python

I have a program which perform different actions depending on the plugins that are passed. For example, python main.py -m foo -m bar will perform the actions of foo and bar. The structure of the ...
1
vote
1answer
68 views

Functionality design: Multiple sources, multiple consumers with configuration

It is a Design Problem which I am listing out here. I have multiple event sources in my app, each one produces events with the different set of data (but each source is producing only one type of ...
1
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2answers
93 views

Avoid mutable field in event handler

I have an event handler that creates objects for which it needs data from both before and after an event. The event handler itself implements Selenium's WebDriverEventListener interface and gets ...
2
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3answers
124 views

How to store objects with inconsistant properties

I have real-world materials that are defined by various properties, some common, some not, that I would like to map to objects in C#. For example, Concrete has properties A, B, C, and Metal has ...
1
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3answers
184 views

Intent of Command pattern?

In Elements of Reusable Object Oriented software by Erich Gamma, the intent for Command design pattern says: Encapsulate a request as an object, thereby letting you parameterize clients with ...
11
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1answer
364 views

Using friend classes to encapsulate private member functions in C++ - good practice or abuse?

So I noticed it's possible to avoid putting private functions in headers by doing something like this: // In file pred_list.h: class PredicateList { int somePrivateField; ...
3
votes
3answers
105 views

Opposite pattern of Template Method

Do we have pattern, which is opposite to Template Method? I mean, in base class we define parts of algorithm and abstract method which implements algorithm. Then in derived class, in that abstract ...
2
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1answer
67 views

How to propagate Setting Class throughout entire project

Here's my setup: Entity Framework Backend Large WPF project that has a main window with 3-4 user controls on it, each of which has 3-4 user controls on it (and so on, in some cases) What I currently ...
7
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4answers
241 views

Improved design for a turn-based multiplayer game using AI?

I'm trying to decide which is the best architecture for a turn-based multiplayer game where the players can be either humans or AI and the UI is optional, for instance because the game can just be ...
0
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2answers
48 views

Methods taking parameter of Collection should filter the collection themselves or be passed a filtered collection?

Say I have this reasonable contrived situation: public class Toast { public bool Toasted { get; set; } public int MinutesToHeat { get; set;} } public class Toaster ...
3
votes
1answer
51 views

Handling field masks on the statically typed client

Let's say I have a REST API, that has the ability to provide field mask (i.e. the API can return M out of N attributes where M is a subset of N). If a statically typed client (example: one that's ...
0
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1answer
61 views

Is it better to initialize semaphores in shared memory or give them as command line arguments? (C++)

I am on a project for which I have to spawn many different processes, all in different executables, and there will be some shared memory segments and some semaphores to synchronize them. I use an "...
2
votes
3answers
279 views

How correct this little game design without removing its design pattern?

Given is a design of a video game in which a player has several possibilities to adjust his character: Game designers realized it's senseless to be a fire-elemental and water-elemental at the same ...
1
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1answer
84 views

“State” pattern and encapsulation

Suppose we have the following classes: As you see, it's an implementation of the State Pattern. Basically, the Order class proxies the pay() and cancel() method calls to it's concrete OrderState ...
1
vote
1answer
123 views

Java Class Design

I need to send a json response. I use the jackson library to convert the class to json. I have a core java class to which I need to add some more fields to create my json response. I came with two ...
4
votes
2answers
234 views

Injecting a dependency that is a tree of dependencies

Is it a pattern or antipattern to inject a dependency that is a tree of dependencies? For example: public class ClassExample { private IContainer _container; public ClassExample(IContainer ...
2
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0answers
70 views

Data processing pipeline design for processing data

I have a use case for which I need to build a data processing pipeline Customer contact leads data coming from different data sources like csv, data base, api has to be first mapped to a universal ...
1
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2answers
646 views

Clean architecture, CQRS, and authentication?

I'm working on implementing my first clean architecture and CQRS application, I've stumbled across a bit of logic that's leaving me a bit stumped. I'm working on integrating authorization and ...
2
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5answers
370 views

Software design pattern for class method that only should be called once

Say I have a TypeScript class: export class TypeCreator { entities: Set<Whatever> registerEntities(e: Set<Whatever>): Set<Whatever>{ return this.entities = e; } } if ...
0
votes
1answer
185 views

Mediator pattern across web API

What are your thoughts on mediator pattern being used from a client and across a web api?, this means: Command definitions are shared between the client and api. Web api exposes only one ...
2
votes
3answers
102 views

How to calculate overall progress in independent phases?

When using a call-back to show progress on a multi-phase task, I don't know how to calculate the progress per phase well. One of the phases is collecting data, which differs in size from run to run. ...
1
vote
2answers
121 views

Dependency injection in a loop?

Suppose I have a loop (in Python syntax): xml = "<x>...</x>" for i in arr: j = f(x) # some complex computation obj = Class(i, j) xml = obj.run(xml) Does it make sense to use ...
2
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0answers
77 views

Python3: How to change the design of a class hierarchy to improve access to objects there buried?

I asked this question already at stackoverflow together with a serialization related part and at codereview for the design part only. Since the design related part receives no answers or comments on ...
1
vote
1answer
113 views

Where and how to handle user password hashing in Clean Architecture?

I'm currently building a new application and trying to apply some of the principles of Clean Architecture. One of my first roadblocks is implementing my own Identity system (to avoid being tightly ...
3
votes
1answer
92 views

If your company ships multiple products, does it make sense to use a mono repo for your integration tests?

Assumption: Each product codebase is in a separate repo. If the product codebase was a mono repo, it would be a no brainer to just put them together. Assumption: Integration tests in this context ...
2
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2answers
88 views

A good way to represent an object with multiple interconnected states?

I want to program a simple budget application. In my application, the budget is divided into budget periods (months by default, but it can be bi-weekly or weekly periods). In each period there is a ...
0
votes
7answers
436 views

Is it a good practice to use self-defined exception?

Our team has different opinions about the practice of using self-defined exception for handling the business logic. Someone says it is good as the exception comes meaningful and readable, and the ...
2
votes
1answer
154 views

Is it efficient and a normal practice to have one class with thousands of lines of code? [duplicate]

I am currently in a continuous software product development project on base of legacy Java code. The source code is very complicated, which is good and bad. But I am surprised to see that in the core ...
8
votes
2answers
162 views

fall-through switch for executing a sequence of steps

My program needs to execute a sequence of steps from start to end. But based on different input the start point will vary, e.g, some will run from the first step to end, some will run from the 2nd ...
0
votes
1answer
111 views

Decorator or Facade

I face an issue if to use a decorator or facade pattern to accomplish my needs. Imagine a client wants to play a video. He can use the interface public interface IVideoPlayer { // Prepares ...
1
vote
3answers
116 views

subclass with no logic of abstract class

I have a class named Change which should be abstract and have some basic methods. I have classes Insert, Update and Delete that extends Change. In the case of Insert, Update I just use extend and add ...
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votes
1answer
36 views

What is an integration test pattern for an extensible permutation of cases (e.g. dimensions of seed data and filtering by said dimensions)?

Suppose we have a service that returns users in certain categories, e.g. Listens to a certain artist. Listens to a certain playlist. Listens to a certain genre. Is between ages X and Y. Is located in ...
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1answer
199 views

Wrong use of factories in Java libraries? [closed]

Some of the Java libraries I have used so far seem to have a Factory for seemingly every other class in the library. Apache's FTP Server project, for example, provides a UserManagerFactory class which ...