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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Do you inject everything explicitly used in a module even if it is loaded in a “parent” module?

When you build a app modularized what do you inject into submodules? Only those things that are used there but not added at the top level, or do you inject everything that is explicitly used in that ...
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Class Library - How to communicate between objects that are not aware of each other?

I am trying to improve my programming skills and knowledge and I have been doing some reading about various design patterns and youtubing videos etc. One subject I thought was interesting was about ...
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Injecting a factory with multiple constructor parameters

Initially I needed only one queue to be created by the MessageQueueFactory: container.RegisterSingleton<IMessageQueueFactory>(() => { var uploadedWaybillsQueuePath = ConfigurationManager ...
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Dependency Injection (DI) and Dependency Inversion Principle (DIP) for built-in functions and external libraries

Question I apologize if this question has already been posted. I tried searching but I couldn't find the answer. I often find myself trying to use DI and DIP where I need to open a file or a socket. ...
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Dependency injection multiple instances or only one InrequestScope

I'm trying to understand what happens with dependencies (Ninject) when a same Interface in injected in multiple classes. I am specifying InRequestScope for my bindings so as I understand there should ...
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Dependency Inversion expands the API, results in unnecessary tests

This question has bothered me for a few days, and it feels like several practices contradict each other. Example Iteration 1 public class FooDao : IFooDao { private IFooConnection fooConnection;...
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66 views

How broad is the definition of “dependency injection”?

What is the "essence" of dependency injection? Is it the idea of dynamically swapping out/in core logical/structural aspects of a program at runtime? Traditionally, this is done in code via some DI ...
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Are there any alternatives to dependency injection for stateless classes?

I am working on an application whereby I have designed classes to fit into several groups: Immutable: initialised through constructors, uses copy-and-swap idiom (inc. move), can deep copy (i.e. ...
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Does anyone have a good DI registration pattern?

I've done this so many times but I never end up liking how my code turns out. I'm asking if anyone else has the same problems and can offer solutions or conventions that they've used to make cleaner ...
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Dependency injection: should I use a framework?

I have recently worked on a Python project where we did dependency injection heavily (because we must in order for the app to be testable), but we didn't use any framework. At times it was a little ...
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Are so called “cross-cutting concerns” a valid excuse to break SOLID/DI/IoC?

My colleagues like to say "logging/caching/etc. is a cross-cutting concern" and then proceed using the corresponding singleton everywhere. Yet they love IoC and DI. Is it really a valid excuse to ...
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Separate interfaces for dependency data providers?

I am attempting to refactor a component of a large project, which currently has a lot of dependencies to global state of the project environment. The goal (for my taste) is a "SOLID" architecture, ...
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163 views

Should composition happen no matter what?

I feel like I should be able to register all my components into the application composition root container no matter what the current state of the environment is, even in the case environment lacks ...
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Ambient dependency injection through static service locator

After some googling I found some debates about whether constructor injection or property/field injection is better, but there is yet another alternative that strikes me as more beneficial. In most ...
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How to avoid a crazy amount of interfaces in UI with dependency injection?

Problem I recently read a lot about Singletons being bad and how dependency injection (which I understand as "using interfaces") is better. When I implemented part of this with callbacks/interfaces/DI ...
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Value of dependency injection in MVC with skinny controllers

Dependency injection is often recommended in MVC projects because it's easy to implement with the pattern and adds a host of potential benefits. Indeed, it actually comes bundled with the default MVC ...
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57 views

Abstract Factories Nesting and DI - Is this acceptable?

I am still trying to get some experience with DI. Let me illustrate my situation and you can give me advice on whether I am using DI and Abstract Factory correctly. I need to create IModels at ...
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107 views

SOLID principles and generating many objects from a file

The "D" in SOLID stands for dependency inversion. If I have for example, a Blacksmith class that depends on Hammer, I should create my Hammer externally and pass it to Blacksmith, rather than having ...
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Constructor Injection vs Field Injection

I know this topic has been discussed a lot already so I don't want to get into which one is the "best way". I have been using field injection for a couple of years now but recently I discovered that ...
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Dependency Injection use in the “Clean Code” by R. Martin

In the Clean Code book by R.Martin, I have encountered the following method on p. 195: private void parseSchemaElement(String element) throws ArgsException { char elementId = element.charAt(0); ...
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How many injections is acceptable in one class when using dependency injection

I'm using Unity in C# for dependency injection, but the question should be applicable for any language and framework that is using dependency injection. I'm trying to follow the SOLID-principle and ...
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211 views

How does a Dependency Injection/IOC Container know which implementation to use?

When you use an IoC container, like so: var svc = IoC.Resolve<IShippingService>(); How does the IoC Container choose which implementation of IShippingService to instantiate? Further, if I am ...
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340 views

Are there any reasons not to use a DI framework on a standalone project?

While researching technologies for a new "pet project" I analyzed a few well-established project's source code and I noticed that they hardly use any dependency injection frameworks at all. For ...
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Repository pattern and Dependency Injection without an ORM

I want to implement the repository pattern in an old legacy project. I already did some research, and found that, without an ORM, it's completely acceptable to have methods like "GetBySpecialProperty"...
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Dependency Injection & In-class Instantiation | Practical Limitations

Dependency Inversion is Good Inversion of dependency is good, it: Simplifies unit-testing Reduces coupling, allowing software components to be used interchangeably Keeps instantiation logic for a ...
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Merits of DI, Abstract Factory implementation review

I'm writing a brand new system and trying to stay true to the SOLID principles, specifically Interfacing and Dependency Injection. We are sticking closely to the Microsoft stack so we are using C# ...
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Mocking third party web service

I am working on a project to create a wrapper library which will be used to interact with a web service provided by the client's IT team. The reason for this library is that we interact with this ...
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93 views

Conditionally creating objects at runtime using Spring.NET

I have a couple classes in a project I'm working on that only register event handlers. public class EventLogger { public EventLogger(EventRaiser someObject) { someObject.EventRaised ...
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Do I have to stop using Dependency Injection to keep object debug printouts small?

Say I have a large object - think EntityManager of an ORM such as Doctrine, or a custom DAO object, or what have you. Object, output of which is required to be used inside a class, but the object ...
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1answer
133 views

Using Spring in Java Project

I've got a question about a correct usage of Spring. I know that some people use the DI "aggressively" so that they always use spring and completely eliminate the usage of word "new" in the ...
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116 views

How far do I separate Model code from Controller code when writing MVC?

I have some code where Controller depends on the Model, and in my case Model acts like a Database Access Object. use FQDN\Model; class Controller { /** @var FQDN\Model */ private $model; ...
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345 views

Only use a dependency injection container at the root of an application?

normally, I'll use a dependency injection container (unity) in c# like this example: class SomeClass { private readonly ILogger _logger; public SomeClass() { _logger = ...
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183 views

Would dependency injecting into entites be considered against SRP?

I asking a question on Stackoverflow earlier and someone pointed me to a previous post of his, He states that injecting a dependency into an entity violates the Single Responsibility Principle. To ...
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Gradually move codebase to dependency injection container

I have a large codebase with a lot of "anti-pattern" singletons, utility classes with static methods and classes creating their own dependencies using new keyword. It makes a code very difficult to ...
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92 views

Where to inject dependency required by all implementors of an interface?

I have an interface whose job is to communicate with repository (that implements some interface). It doesn't seem to make sense to implement this interface without receiving a repository,so I'd like ...
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642 views

How do constructor parameters of a MVC Controller get set?

How does the construction injection work? I have the following code: public class AdvancedSearchController : Controller { private EmployeeController _employeeController; public ...
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160 views

Circular dependencies: Recursive grammar parser (e.g. json)

(TLDR) To build a parser for a recursive grammar by composition of individual parsers (e.g. with a parser combinator framework), there are often circular dependencies between some of the individual ...
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2answers
138 views

Having a TestContext to test methods instead of Dependency Injection

I am working on a legacy code base and I need to find a way to write unit tests for this project. The project has a three layer architecture (UI-Biz-DAL as we call them) and DAL is totally ...
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Using Python's Method Resolution Order for Dependency Injection - is this bad?

I watched Raymond Hettinger's Pycon talk "Super Considered Super" and learned a little bit about Python's MRO (Method Resolution Order) which linearises a classes "parent" classes in a deterministic ...
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Legitimate “real work” in a constructor?

I am working on a design, but keep hitting a roadblock. I have a particular class (ModelDef) that is essentially the owner of a complex node tree built by parsing an XML schema (think DOM). I want to ...
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240 views

Anemic domain models and domain services injection

The anemic domain model is described as an anti-pattern in domain driven design by Martin Fowler. To have business logic on the domain models often domain services are used. But injecting domain ...
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4answers
138 views

Is it ok to use service locator for ubiquitously used dependencies? [closed]

We strictly adhere to inversion of control in our codebase, but that creates hellish constructors (yes, I know that means our classes aren't cohesive enough, this is a work in progress). The thing is, ...
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148 views

What does `Resolving` mean in programing? [closed]

I see many places where the word Resolve is used, in Dependency Injection (resolve an implementation to an interface), Package Manager (ex: Resolve packages dependencies), Web (ex: Resolve a hostname)....
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IoC container with lifetime attribute [closed]

Which ioc frameworks for .net can use concrete type attribute to choose it's lifetime? Here is a simple example public interface IService {} [Singleton] public class ServiceImplA : IService {} [...
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4answers
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Dependency Injection: Field Injection vs Constructor Injection?

I know this is a hot debate and the opinions tend to change over time as to the best approach practice. I used to use exclusively field injection for my classes, until I started reading up on ...
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4answers
256 views

Reusing the logic in another repository in ASP.NET MVC repository pattern

I have an ASP.NET MVC4 web application, with EntityFramework for data access. In the application I have two repositories as follow (this is only an example not my real code): public class ...
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1answer
332 views

Does Having DI Happen in the Composition Root go against the whole point of Dependency Injection?

I am using Dependency Injection for a .NET MVC web application in which I have three basic layers: 1) Web App 2) Service Layer 3) Data Layer I inject the data layer into the service layer and the ...
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29 views

Dealing with stubbed external dependency

In sut I should I have two kinds of dependencies to be stubbed: 3rd party dependencies (mongodb & co) and own dependencies: var async = require('async'), // This dependency should not be stubbed ...
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Why do we need frameworks for dependency injection? [closed]

I've been reading up more on the Inversion of Control principle and Dependency Injection as an implementation of it and am pretty sure I understand it. It seems to be basically saying 'don't declare ...
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537 views

Doesn't dependency injection push the testing burden further down the chain?

I'm learning about dependency injection and while I can see the appeal of it when writing functional libraries, I fail to see how it solves anything when you'll also be the one using the libraries. ...