DI, dependency-injection, is a design pattern where dependencies (instances of objects, properties) of a component are set through the constructor(s), methods or fields (properties)

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Is it possible to define injection rules based on Spring bean scopes?

My application is using Spring as my dependency injection framework. I have been struggling recently with nasty concurrency and security bugs. The bugs were caused by injecting bean with incorrect ...
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63 views

Is there a name for the anti-pattern of over-using event busses for uncoupling?

While global event busses can certainly help to previously tightly coupled code, they come with a big cost when applied impetuously and oftentimes conflict with dependency injection. Let's assume we ...
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95 views

What is the motivation behind the @ImplementedBy annotation in Guice?

I recently read about the @ImplementedBy annotation available in Google Guice. It allows the programmer to specify a binding between an interface and its implementation for future use in dependency ...
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44 views

Polymorphism on repository interface for local and remote operations

I'm in the process of designing a facade ApiClient class that would abstract some CRUD operations between a local database and a remote one (through a REST web app). Said ApiClient class depends on 2 ...
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47 views

Class Interfaces with Multiple Classes and Dependency Injection

NOTE ON QUESTION TITLE: I did not really even know how to phrase the title so if someone can edit and make it more articulate I would really appreciate it. QUESTION: Basically, what I'm trying to do ...
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185 views

Injecting collections as constructor dependencies

We are using constructor dependency injection in our application. Following that approach we inject everything using an injection container so we are able to replace any dependency with a Mock. Some ...
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145 views

Factory for creating a singleton instance

We have some legacy code that has a bunch of singletons all over the place (written in C#). The singleton is a fairly "classic" implementation of the pattern: public class SomeSingleton { ...
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209 views

Static console object or dependency injection?

For a current project I have created a Console class which wraps up C++'s usual cout, writes output to a file or uses Console::WriteLine depending on the environment. Currently I've setup my code base ...
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2answers
132 views

Dependency injection vs dependency lookup in a layered architecture

Given a layered architecture, where the business logic is isolated in a package from all other layers, like persistent storage, user interface, interfaces for various (vendor) remote services, etc, I ...
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1answer
76 views

Transient life time and constructor injection

I'm working on a little light weight Dependency resolver found here https://github.com/AndersMalmgren/DuoCode.SimpleInjector Currently if you do var instance = container.Get<Foo>(); You ...
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5k views

Should one use Dependency Injection even if the class is used only once? [duplicate]

During a code review I have started having a bit of a dilemma as to whether use dependency injection or not. I would like to hear your thoughts, because this is kind of an ongoing theme and would help ...
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1answer
86 views

Pick dynamically the right Factory Class with Inversion of Control

I have a TreeView and I want to enable the context menu when clicking with the right mouse button. It is composed by items from different classes, but they all share the same base class. So, I was ...
2
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1answer
194 views

Hidden dependencies - why not?

Hidden dependencies: function __construct($dep_registry){ $this->db = $dep_registry->get('db'); $this->request = $dep_registry->get('request'); ... } Not so hidden: function ...
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91 views

Multiple method calls in the constructor and dependency injection

I was asked to refactor some almost ureadable spaghetti code into object-oriented architecture. I have some doubts regarding a class that I designed. Here is the class' skeleton: require_once ...
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2answers
105 views

Rich Domain Models, Encapsulation, and the Problem of Constructor Over-Injection

I am refactoring an e-commerce web-application, currently working on the UserBasket class, which will have to handle adding or removing items, changing their quantity, getting total amount, total ...
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149 views

Dependency Injection with EF - is mapping required?

I'm implementing the Repository pattern with using DI and EF6. I created the database (that inherits from DbContext) object with the Visual Studio wizard ADO.NET Entity Data Model I have a generic ...
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185 views

Sharing state with dependencies - Object-Oriented Design

Suppose that I define two interfaces below: public interface IReader { void Read(string bookName); } public interface IWriter { void Write(string bookName); } Now I want to implement ...
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3answers
466 views

Is Functional Programming a viable alternative to dependency injection patterns?

I have recently been reading a book entitled Functional Programming in C# and it occurs to me that the immutable and stateless nature of functional programming accomplishes similar outcomes to ...
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6answers
3k views

When NOT to apply Dependency Inversion?

I am currently trying to figure out SOLID. So Dependency inversion means that any two classes should communicate via interfaces, not directly. E.g. if class A has a method, that expects a pointer to ...
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137 views

Does merely parameterizing a dependency meet the requirements for Inversion of Control?

When I find a concrete dependency inside an extension method, I have been attempting to remove the (concrete) dependency by parameterising it like so // original implementation public static ...
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184 views

Is circular Dependency Injection a good practice?

I'm trying the Dependency Injection pattern in some new classes, more specifically in a Transaction System and stumbled into a dilemma. I have a Person class with a create_new_transaction method, and ...
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68 views

Is this pattern of optional dependency injection sound? [duplicate]

A lot of the time when working on legacy code bases, I find it hard to move manually created dependencies to the constructor parameters, because of a variety of reasons. Sometimes it's because the ...
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1answer
126 views

What is a good practical example demonstrating an architectural advantage in interface dependency injection

I need help (preferably by way of a practical example) to understand why/if the following implementation of IoC/DI (in this case using Ninject) provides an architectural advantage: using (IKernel ...
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2answers
248 views

How can I avoid tight coupling when practically every decision-logic has to check lots of distributed state?

As the senior developer in our company, I am currently starting to move our commercial php-mysql e-commerce solution (which takes data from a specific ERP-system) from procedural spaghetti-code which ...
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1answer
103 views

Creating variables in methods/functions

In how far do we create variables in our methods or functions? Do we only create one when we're using the result of the variable more then one time like this? function someFunction(SomeClass ...
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1answer
128 views

Inject it or create a new instance

suppose i have an interface in some language with two simple methods interface IConverter{ String toString(Object o) Object fromString(String s) } this interface is implemented by many ...
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147 views

Are prototype beans with constructor parameters an anti-pattern?

Reading on this, Misko Hevery has said “Newables can ask for other Newables in their constructor, but not for Injectables” Now it appears to me that requesting a prototype be instantiated at run-time ...
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This way I'm writing this code is testable, but is there something wrong with it I'm missing?

I have an interface called IContext. For the purposes of this it doesn't really matter what's it does except the following: T GetService<T>(); What this method does is look at the current DI ...
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550 views

Initialize in Field, Constructor, or Argument

If I know what a field will be initialized to, should I initialize it in the field, constructor, or receive it as a parameter? I am asking about best practices. All three options effectively provide ...
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1answer
120 views

What is a relation between Dependency Injection, single instance, and singletons?

I read So Singletons are bad, then what? which was a great explanation of dependency injection as the solution for inversion of control. The asker assumed singleton and single instance were synonyms, ...
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449 views

Is it bad to use DI to inject constructor parameters at runtime?

These are two classes, the first one I inject an instance of type IEngine while the second one I inject owner's name, tickets and engine. Version 1: public class Car { public Car(IEngine ...
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340 views

Simple Injector in Onion Layer Architecture

I'm trying to find a good resource, advice, etc in a project I've taken on for myself at work. Background When I started here we had a application that was part MVC part Webform (separate projects ...
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1answer
91 views

How to manage coupling in model classes

I'm doing a class diagram for a game project, but I'm stuck on a coupling problem. Context The projet is a turn-based game. Two users are playing. They've got units on a map. They play until 1 ...
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45 views

How to clean composition root from anything other than object construction?

I'm doing poor man's DI (manual injection) in my application. My (pseudo-) composition root looks something like this: var connectionSettings = new Settings(SqlParameters) var dataLoader = new ...
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225 views

IOC Between Presentation and Infrastructure Layer

Question: I would like to set forth dependency mapping from a *.config file from a project that has no reference to the project that contains the concrete class. Scenario: I'll be using terms from ...
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281 views

Issues about static injection in Spring?

I use spring-boot with spring xml in my project. I wrapper the DAOs in a DataAccessService class to serve as a DB service layer, both the service and the DAOs are injected in spring xml and used by ...
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2answers
232 views

IoC as service locator

I have been wondering for quite some time on some issues while using dependency injection: In a layered application, I normally inject repositories into the application service using constructor ...
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3answers
281 views

Why does dependency injection encourage collaboration to be exposed via constructors?

The general approach to DI that I see in answers like So Singletons are bad, then what? encourages business objects that collaborate with other objects to (a) not directly create those instances and ...
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1answer
257 views

C# Dependency Injection Placement

This is my first time using Unity so bear with me for a moment. I have a sample Visual Studio 2012 project with 4 projects (but only two of these projects will be used with Unity). This is the ...
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103 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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1answer
62 views

Data serialization architecture, injection on construction vs. on function call

I am creating a data serialization/deserialization mechanism for essentially a persistent storage object. Due to the variety of systems this mechanism could run on, there needs to be a a variable ...
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2answers
267 views

when using dependency injection, should I always pass an interface

When using depending injection, you generally pass everything around as an interface (perhaps with the exception of primitives and strings). That allows you to easily chance the behavior, without ...
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3answers
902 views

I get dependency injection, but can someone help me understand the need for an IoC container?

I apologize if this seems like yet another repeat of the question, but every time I find an article regarding the topic, it mostly just talks about what DI is. So, I get DI, but I'm trying to ...
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2answers
198 views

Why do IoC containers provide public Resolve method(s)?

In my opinion it just inverses the inversion and could make new users (including myself) make incorrect assumptions about using IoC containers. It can be used for the Service Locator (anti-)pattern ...
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1answer
196 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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3answers
263 views

Reducing dependency cycles and reducing coupling

I'm trying to learn how to produce quality object-oriented code and have been studying concepts like SOLID. I'm currently working on an entity-component-process system for a small game engine. ...
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1answer
103 views

Value Object: static factory or assisted injection?

First let assume that everybody agree that there is nothing wrong with injecting some value object into injectable object such as service. Indeed, a service can get another service injected, but could ...
2
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2answers
314 views

Dependency Injection: where to store dependencies used by only one method?

I am developing a project integrated with Dependency Injection (just for reference, I'm using Unity). The problem is that I have some Manager classes with several methods and in many cases I have ...
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5answers
584 views

Questioning one of the arguments for dependency injection: Why is creating an object graph hard?

Dependency injection frameworks like Google Guice give the following motivation for their usage (source): To construct an object, you first build its dependencies. But to build each dependency, ...
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224 views

Ninject/DI: How to correctly pass initialisation data to injected type at runtime

I have the following two classes: public class StoreService : IStoreService { private IEmailService _emailService; public StoreService(IEmailService emailService) { _emailService ...