Questions tagged [design-patterns]
A design pattern is a general reusable solution to a commonly occurring problem in software design.
4,419
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How does a Bounded Context from DDD help scaling microservices?
New to the microservices architecture - but what I've picked up so far doing some research while designing a microservices architecture for a home rental system is these:
Individual microservice ...
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Separation of concerns: persisting complex types
I have the following module structure:
core
persistence
extension
In my core module, I have an interface: Handler. This interface has multiple implementations in the core module as well as extension ...
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How do I structure my functions (and classes?) which interact with my Database/ORM?
So I am working on my first project using SQLite and SQLModel as ORM. Creating and handling the first table in my database was easily structured: A function for each CRUD-Operation.
But now I have ...
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How to design fault-tolerant distributed "all-or-nothing" system?
I have a system where Client(C) sends request to Server(S0). S0 then sends the response back to Client that "request received" and closes the connection. C can regularly poll S0 to check on ...
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Shell Script Design Patteren: Source a library file VS Call different files?
We discuss about POSIX compliant shell script here.
While we are writing more and more shell scripts, we build some helper functions to reuse the codes.
We are considering putting a few helper ...
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Appropriate design pattern for providing a default Argparse instance, eliminating boilerplate
I'm using argparse.ArgumentParser extensively; however, it comes with a lot of boilerplate to set up, and this is especially noticeable when you've got more than a few common arguments that probably ...
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158
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Pattern to transform and cache data from a DB?
We have a server that receives queries. We use the command pattern for this, e.g.
q := NewQuery(database)
q.Execute(request1)
q.Execute(request2)
The queries read a "model" from the ...
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102
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Decorate class which inherits from concrete class(es)
In my project I have several "basic" interfaces whose behavior is fixed, i.e. the default implementation will always be good for every puropse. So I defined them as concrete classes with ...
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Load Testing for Large-Scale Architecture Involving Cloud Servers and Switches
We currently have an architectural setup as described below. Our plan is to conduct a load test, but we face a challenge due to the high cost of real switches. We have two options: either build the ...
- 101
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Designing message handler
I am writing an application that receives different kinds of messages from an external device. The messages are of different types and they are received from the device in the form of a string.
For ...
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How best to share common steps between services while allowing them to provide their own behaviour
I've started working on a C# codebase. There are three services which run the same set of steps of three kinds of objects, each returning IResult:
public IResult FooService(Foo foo) { ... }
public ...
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153
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Design patterns for long chains of computations in python (functions vs classes?)
A recurring pattern which I see in my code is chaining together a lot of functions. This is the result of a large number of processing steps needed for a given task. This could be e.g. a data ...
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better structure of a software project to prevent circular dependencies
I am contacting you today regarding a recent problem with circular dependencies. It's about a Spring boot application that accepts data via a Rest API and then forwards it to an internal Spring ...
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129
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Serialization pattern and code duplication
I noticed how our codebase contains multiple versions of the same method, which unmarshalls the inbound byte-stream into java objects and that the only difference between the current and previous ...
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Multiple-operations method pattern
I don't know the name of this pattern but what is the purpose of such methods:
AddOrUpdate
GetOrAdd
instead of single-operation ones?
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What are standard ways to pass the event signal over fixed level only connection?
I need to pass exactly event (not a lasting state) over communication connection that can provide boolean or integer value, possible to set, clear and observe by both sides. It is OPC UA framework but ...
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Refactoring a "filter" design
I need to refactor a class that became too messy. The class has a method that reads some raw data from one of our repositories, and another that "filters" it:
The data is in the form of ...
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Can 1.0.1 be launched right after 1.1.0?
I know that it is common for software to have parallel development in major versions, such as v1 (1.x.x), which can be completely different from v2.
Regarding Semver (Semantic Version), can I upgrade ...
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Is it okay to combine bff and rest api?
I'm building an application related to donation on streams.
And I have such models as "alert" and "alert-template".
"alert" is a set of different parameters to understand ...
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Spring data exchange between components?
Please advise me what pattern to use in following case:
I have a Java/Spring Boot application. There is a component with @KafkaListener method which receives Kafka Messages on CRUD of various subject ...
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How to reconcile the fact that dependency Injection break encapsulation? (Especially when others are allowed to wire up your dependencies for you)
I was reading Martin Fowlers take on Dependency Injection, and in general have been trying to discuss it a bit online to help get rid of my own misconceptions and to understand this principle better.
...
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Did the term "decorator" originate with OOP design patterns?
The Decorator pattern allows behaviour to be dynamically added to an existing object, effectively "decorating" it with new behaviour. While the pattern as formalised and named seems to have ...
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For more than one parameter, when NOT to introduce parameter object?
I know there are some questions about "Introduce parameter object", eg: Is "Introduce Parameter Object" actually a good pattern?, Should we avoid custom objects as parameters?, ...
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Please explain the "swapable dependency" arguments for IOC containers
I get that IOC containers can be useful to help break dependencies and allow you to test a class in isolation. I don't wish to focus on that right now, instead, I'm trying to understand some of the ...
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Decide pattern(s) for Background service which has dependency on services and service-provider and ServiceBus in .net
I'm designing class library with background service which has
public static class ServiceCollectionExtensions
Which have few methods which will be call outside.
Now above mentioned extension will ...
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83
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Access Token Or Alternative for Microservices For Resource Level Granular Checks
Hi I have following structure :
Client App (layer 1)
Business logic Services ( Layer 2)
Business Logic layer consists of many microservices . Access token can be created and passed from APP layer to ...
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In poltergeist, whats wrong with "solely to trigger or initialize several other objects"? Isn't it is a good use of encapsulation and reuse?
After reading What differentiates function objects from poltergeists?, according to the definition of poltergeist, I still don't understand why would "poltergeist" be a bad pattern:
A ...
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How could I apply the strategy pattern to a react component? [closed]
For the following component, how would I extract the unit logic to allow for composition? In my actual app I am trying to reduce the amount of logic encoded in the component and I have decided that ...
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9
answers
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Is it an anti-pattern to use interface for entity?
I read an article about that using an interface for an entity is an anti-pattern for these reasons:
Your interface signature is identical to your class.
There’s only one implementation of your ...
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What C# Object Composition strategy would you apply for CoreObjects with a governing 'ObjectType' property
In a C# ASP.Net Core Web Application I have a Domain Model CentralDesignObject made up of many component objects & properties, producing a significant amount of derived/calculated values.
This ...
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347
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How encapsulating what varies can help us?
I have a question about encapsulation and I read these two topic (this & this) but I got more confused.
I've been reading Head First Object-Oriented Analysis and Design book and I'm trying to ...
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Is this a bad pattern for reporting/audit?
We have a large code base with lots of workflow data (camunda) that does this:
Create a reporting event in the codebase
Give it a code + payload
Put the item on a message queue
Consume queue ...
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Java - How to build a library to record runtime data?
I'm working on building a library in Java which could provide the ability to record runtime data.
For instance consider the below code:
public interface ItemElement {
public int accept(...
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163
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Event-driven design with delayed consequences
EDIT: more direct situation
I need to design a program that will create particular objects and run computationally intensive procedures using its fields in order to update other fields. When a ...
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Implementing MVC in C++ with minimal boilerplate despite lack of reflection
Powerful reflection capabilities make implementing nice architectural design patterns such as MVC and Dependency Injection very simple in languages like Java and Kotlin. In particular, reflective tags ...
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113
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Best way of creating different instance types(facotry method) with business logic?
Say I am trying instantiate an instance of a Table. Table here denotes a restaurant table used for eating. Say I have 3 different table types
enum TableTypes {
SMALL,
MED,
LARGE
}
I have ...
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What is the name of the approach (practice) when several unrelated entities are returned at once in the response to a request [closed]
For example, for a mobile frontend, you need to get all the data for rendering at once. The interface is divided into blocks, in which there can be both blocks with a catalog (categories) and other ...
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364
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Is MVVM appropriate for a .NET MAUI Blazor hybrid app?
I am preparing to create my first .NET MAUI Blazor hybrid app. It is a relatively new technology so there aren't a ton of resources to look at, but of the ones I have found, they are all structured ...
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Domain models: Can they be an abstract class
When talking about having a rich domain model successfully, in real applications, it needs to, somehow, access some abstraction of complex functionality (instead of being a row state calculator the ...
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How to avoid repeating "a==b" when comparing "condition a" and then "condition b" and then...?
For example, I have an object:
public class Obj{
public int a;
public float b;
public String c;
}
I need to find best "Obj": largest a and then largest b and then longest c:
int ...
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Design of system pushing data to multiple systems
I have a ASP.NET Core backend (with Azure Service Bus) and a Blazor Server frontend.
The purpose of the backend and the frontend is to trigger manual and automatic pushing of single data points (...
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Some approach or Design Pattern to implement same method different parameters of Interface class
I am using the Flyweight pattern to cache and reuse objects of the different classes. For example, I have a Shape interface class and multiple types of Shapes implementing the methods from the ...
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Use of Visitor pattern rather than enums
Lets say that a enum exists:
public enum SomeEnum
{
FirstValue,
SecondValue
}
It's use is spread through the code and all sort of wonderful logic hangs off it.
If we now add another entry (...
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design pattern to avoid deadlock with mutex in golang
What would the appropriate design pattern to avoid deadlock when several functions use the same mutex ?
It is quite easy to forget what method uses the lock and so it happens that you call a function ...
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Converting the classes with multiple dimension to Bridge design pattern
Bridge design pattern is something which is very confusing and GOF does not do justice with beginners in the definition.
I was asked in my current organisation to add one more dimension to our class ...
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Dealing with global variables required by badly-written library
I am working with a library that is somewhat poorly written. In order to function, it requires several global variables to be declared and sometimes even maintained by my own code. I really don't ...
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Choosing a Pattern for Handling Different View Models in a Service Method
I'm working on a fairly large but standard dotnet core API. Here's a simplified sample:
// Simplified example of a controller
public class VehiclesController : ControllerBase
{
private readonly ...
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What are the pros and cons of different combinations of objects and arrays for data storing?
From the article JavaScript 2D Array – Two Dimensional Arrays in JS, I see one way to store data is to put all properties of each element into one array:
let dataRepresentation1 = [
['John Doe', ...
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Is having many thin factories an antipattern?
I need to perform the following task: for a user [email protected], store a blob of data into their dedicated data store.
DataStoreService is what actually stores the blob of data in the user's store, ...
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Why is Dependency Injection called "alternative of global state"?I think global state still exists
According to Why is Global State so Evil?, I believe we should avoid global state, so suppose I have an App that count user clicks in all pages like it:
public class GlobalState{
public int ...
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