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

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JavaScript & AngularJs Modules Implementation technique and structure

So Im building an app and I'm trying to implement the structure of the app so that its robust and scalable in future. My app is mostly divided into JavaScript Modules (revealing pattern): // filter....
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159 views

Is IntentService an implementation of Command Pattern?

According to Wikipedia: In object-oriented programming, the command pattern is a behavioral design pattern in which an object is used to encapsulate all information needed to perform an action or ...
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115 views

Option<T> functional type implementation and scenarios

Have you ever being implementing Option<T> functional type? It is discussed here: https://app.pluralsight.com/library/courses/tactical-design-patterns-dot-net-control-flow/table-of-contents ...
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How does the copy and paste mechanism work and is it a standard design pattern as in GoF?

How does the current copy and paste work on a computer? Such as being able to copy some formatted text together with an image, and then when pasted to a text editor, it will intelligently paste only ...
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91 views

Message Mapper Design Considerations

Long question context, skip to tl;dr for the meat of it. I am designing an integration between two web applications, and have come to the conclusion that a message pattern would be an appropriate ...
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1answer
118 views

Intelligent builder pattern - different parameters depending on type - generics?

Lets say we have the famous Joshua Bloch Nutrition Builder and we want to change it so it be a bit like dynamic builder which restricts visibility of setters and propably uses generics : public ...
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Is it a good practice to use List of Enums?

I am currently working on a system where there are Users, and each user have one or multiple roles. Is it a good practice to use List of Enum values on User? I can't think of anything better, but this ...
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(Re)structuring a Qt Project [closed]

A PySide project I've been working on for a while now has started to grow to a point where it's becoming large enough that I've had to step back and re-think the overall design. I've spent some time ...
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2answers
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Design pattern for abstracting interaction between multiple resources

So far I've been building applications abstracting data entity operations behind the use of Repositories. Each of them would encapsulate the domain that corresponds to their defined entity. For ...
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Building a generalized notification system: passive vs. active

Recently, I've tried my hand at building a notification system, but I quickly found that notifications are tricky things, especially in the context of building a general model. The diversity of what ...
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461 views

Parallel hierarchies - partly same, partly different

There are quite a few similar questions out there 1, 2, 3, 4, but non seems exactly the case in this question, nor do the solutions seem optimal. This is a general OOP question, assuming polymorphism,...
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Advantages of having multiple apps or sub apps SPAs in AngularJS SPA

Having you application comprise of multiple child apps is good for readability and debugging. However, other than that is there any advantage over performance or memory management or Garbage ...
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220 views

Using prototype/non-Spring managed beans in Spring Web application

I have been working on few web applications/REST web services recently (Spring IoC/MVC/Data JPA etc) and they usually follow the same pattern: Controller classes --> Service classes (which have number ...
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3answers
196 views

Command pattern and open-closed-principle

Does the command pattern uses OCP ? In a command patter the invoker is only extensible by actually extending the class. If we want to add custom methods to it, we can make our own sub-class or we ...
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57 views

Repository Pattern Class Collection examples with Lazy/Eager loading

When implementing the repository it's fairly easy for a stand alone class. Unfortunately, we are unable to use an ORM to manage our data access, so I'm trying to recreate some of the functionality ...
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1answer
113 views

Improving sampling algorithm

I am having a bit of trouble designing a new feature at the moment. It is part of a resource management system. I was wondering if anyone has experience doing anything similar. I'll try to explain: ...
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150 views

Making more than one instance of factory that is supposed to be singleton

However, there are some classes that should have only one instance. Sometimes they are factories, which you can use to create the other objects in the system. If more than one factory exist, ...
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3answers
181 views

What is the correct name for this data object?

I need to understand the proper name for an object that has cropped up in two projects now. Here is the conventional representation for the MVC pattern: However there is another "Model" that is ...
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1answer
154 views

Understanding Generic Repository Pattern

I am trying to understand the generic repository implementation. I have seen this line (or similar to it) in many examples: public interface IRepository<TEntity> : IDisposable where TEntity : ...
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174 views

Handling multiple asynchronous events - Wait for pending offers to process on new offer?

I have a programming problem, that I don't know how to solve. And while I have provided a sample of my code, I am interested in a conceptual answer on how to resolve this problem. On a tradeOffers ...
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1answer
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How to implement Singleton on a Resource / ResourcesManager case?

This is a design pattern academic question exercise. We have a Resource class and a pure fabrication class ResourcesManager to manage objects w/ type Resource. The question is Given the following two ...
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Implementing “buy one get one for free” coupon logic for shopping cart

Trying to solve bogo coupon logic with proper design pattern, but having trouble identifying one. Use case: "Buy iPad get SmartCase for free" Suppose we have the following objects: Product: - ...
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2answers
505 views

is it bad practice that controller call repository instead of service?

is it bad practice that controller call repository instead of service? to explain more: I figure out that in good design controllers call service and service use repository. but sometimes in ...
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2answers
184 views

Strategy Pattern Implementation

I have to generate a code that will send through SMS or Email to implement the One Time Password (OTP) requirement of our client. I just finished creating the design using strategy pattern, . . This ...
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1answer
94 views

How to represent data objects gradually getting augmented in a pipeline [closed]

I'm working on a Scala data-processing program. Essentially we start with a collection of many small data objects, say, (eventId: String, basicInfo: Basic) and gradually filter out some objects and ...
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2answers
110 views

Which design pattern to choose when supporting multiple analytic tools?

I have spent quite some time learning all possible design patterns but I cannot find the ideal one for the following case. I am developing an iOS app where we are using multiple analytics tools like ...
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173 views

Which design pattern is it if any for providing a general logger interface?

I have a library where I want to use a logger but I don't have (and cannot) create any interface for it because I'll be using it on different systems that have nothing in common (and won't have). So ...
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Alternative to Anemic domain objects (Simple example provided)

I want to model (TV)Events and Reminders and I’m wondering what’s ‘the best’ way to model this. The requirements are roughly When an Event has no Reminder, a Reminder can be created When an Event ...
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Name of design pattern for single-observer

Is there an existing named software design pattern similar to Observer, but for the case where only a single observer is supported rather than a collection of observers. I find that I use this ...
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Designs and practices to guard against erroneous null entries from database

One part of my program fetches data from many tables and columns in my database for processing. Some of the columns might be null, but in the current processing context that is an error. This should "...
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8answers
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Refactoring a long method which is based on large number of switch cases [duplicate]

We are using Java as a backend development language. One year back, we wrote a method which uses switch cases based on Enums values. Since we are continuously adding enum members and according adding ...
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Convention for exception argument order [closed]

Just a quick question about a design pattern for creating custom exceptions. The question is more about the order of parameters. If you can specify more data in the exception, should the parameter for ...
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3answers
2k views

How to solve circular dependency?

I have three classes that are circular dependant to each other: TestExecuter execute requests of TestScenario and save a report file using ReportGenerator class. So: TestExecuter depends on ...
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1answer
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Builder Pattern : Seperation of construction from representation

I am reading GoF, and the intent of builder is mentioned as to separate creation of complex object from its representation. I couldn't understand what representation means in this context. What does ...
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Is there a design pattern to remove the need to check for flags?

I'm going to save some string payload in the database. I have two global configurations: encryption compression These can be enabled or disabled using the configuration in a way that either only ...
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Can this be used to implement Post Redirect Get pattern?

I am trying to implement proper a Post Redirect Get on a PHP site (question is language agnostic in nature however). I thought about it, and realized that running this code on every request seems to ...
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108 views

Pass request as argument to service client vs. pass service client as argument to request [closed]

I need a design recommendation: I have a class that send a http request via another class WebServiceHandler() I am hesitating between the following two implementations, which one to choose?which one ...
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1answer
110 views

Does my design break modularity and loose coupling?

I want to know if my implementation is modular and loosely coupled such that pieces can be replaced easily. Any concrete class that extends the abstract class HexGridLayout will be expected to ...
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0answers
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Should my application call statsd directly or should I call statsd based off logs?

I'm planning on incrementing counters in statsd based of various events within my application. I have logging in place for these events. So, from my viewpoint I have two options: Update the ...
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70 views

How can I create a client for a service without hiding the parameters needed for each endpoint?

I'm creating a client to a third-party soap web service in my application. Here is the way I'm thinking of doing it: Create a ClientFactory that makes a client based on the wsdl file, and sets ...
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Design pattern for “operation on object allowed, only if object is in certain state”

For example: Only job applications that are not yet in review or approved, can be updated. In other words, a person can update his job appliance form until HR starts reviewing it, or it's already ...
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Which design pattern for interaction with miscoded project [duplicate]

I am actually working on JavaEE application (Spring, Hibernate). I have an old project which is not well coded. I have to not modify any line of code on it. And I have to add classes that uses this ...
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Is it a good idea to define one big private function in a class to maintain valid state, that is, to update the object's data members?

Although in the code below a simple single item purchase in an e-commerce site is used, my general question is about updating all data members to keep an object's data in valid state at all times. I ...
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1answer
208 views

Should UDP & TCP port numbers represented as a short or integer?

I am currently designing some networking code, and this code expects the caller of the code to give it a port and hostname to connect to. Since I am still in the development phase, I can still change ...
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What is the difference between Adapter and Delegation design pattern?

I am very confused about Adapter and Delegation design pattern. In Adapter pattern we bring an intermediate class to interact with another class. And in Delegation pattern we also bring an ...
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How do I associate command objects with the right receiver?

I tried to use Command Pattern for implementing Undo and Redo in my project public abstract class Command { protected Form Receiver { set; get; } protected HtmlElement Element { set; get; } ...
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1answer
151 views

What is the alternative design pattern of a state machine that may have recursive state change?

I have a state machine like code, which has state A,B and C, with a function changeState(char i) which can change the state of a system, and each state can also call changeState(char i) to switch the ...
2
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2answers
270 views

Java Game. Preload objects and reuse vs create objects at runtime [closed]

I'm currently developing my first game in Java language. The game is an endless runner with obstacles to avoid and enemies to kill. Unfortunatelly im still not experience enough and many times im ...
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361 views

Is it true that for Observer Pattern to work, there probably is some polling mechanism underneath?

The short question is: is it true that for Observer Pattern to work, there probably is some polling mechanism underneath? (update: in a network situation) It was quite amazing that if on my Macbook ...
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Is “StringBuilder” an application of the Builder Design Pattern?

Is the "Builder" pattern restricted to addressing the "telescoping constructor" anti-pattern, or can it be said to also address the more general problem of complicated creation of immutable objects? ...