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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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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638 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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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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272 views

Spring StoredProcedure Inject declared parameters or not?

At work one of my colleague asked to me to change the way a Spring StoredProcedure subclass class was initialised from injecting the parameters with Dependency Injection mechanism (Constructor ...
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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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167 views

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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818 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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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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Dealing with an often occuring dependency that is not related to the class

I'm using view classes for my templating. These view classes often require the Routing class to get URI's from other pages. You could actually say that the Routing should be available to every view ...
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Interception vs Injection: a framework architecture decision

There's this framework that I'm helping to design. There are some common tasks that should be done using some common components : Logging, Caching and raising events in particular. I am not sure if ...
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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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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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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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126 views

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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1answer
331 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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4answers
3k views

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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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. ...
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58 views

Can a DI object be both a client and a service simultaneously?

In my reasearch of Dependendcy Injection so far I haven't seen an example object being treated as both a client and a service (meaning a service [value, factory, etc] which has its own dependencies). ...
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628 views

How is an interface used in Dependency Injection?

I'm working on a simple DI library, and on the subject of using services through interfaces, I can't find the usefulness. Perhaps it's because I dont fully or properly understand how an interface ...
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Dependency injection ; good practices to reduce boilerplate code

I have a simple question, and I'm not even sure it has an answer but let's try. I'm coding in C++, and using dependancy injection to avoid global state. This works quite well, and I don't run in ...
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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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How do things other than services fit into the Dependency Injection pattern?

Wikipedia explains: A dependency is an object that can be used (a service). An injection is the passing of a dependency to a dependent object (a client) that would use it. But studying ...
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Does this structure satisfy the terms of the Inversion of Control principle?

I'm trying, as a test, to create Dependency Injection from scratch in JavaScript. Consider the following code structure, which outputs an Alert: Does it satisfy the terms of the Dependency Inversion ...
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What should a Dependency Injector look like in JavaScript?

I'm studying Dependency Injection in JavaScript. I've learned what I need to accomplish, according to Wikipedia, The client delegates to external code (the injector) the responsibility of ...
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What are the benefits of dependency injection in cases where almost everyone needs access to a common data structure?

There are plenty of reasons why globals are evil in OOP. If the number or size of the objects needing sharing is too large to be efficiently passed around in function parameters, usually everyone ...
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DI and hypothetical readonly setters in C#

Sometimes I would like to declare a property like this: public string Name { get; readonly set; } I am wondering if anyone sees a reason why such a syntax shouldn't exist. I believe that because it ...
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Constructor Injection vs. IocFactory

Today at work a collegue and I had a discussion about the following: Basically we have a rule engine which works in the following way: RuleExecutor Gets all rules to execute in the constructor ...
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C++: Should class own or observe its dependencies?

Say I have a class Foobar that uses (depends on) class Widget. In good ol' days, Widget wolud be declared as a field in Foobar, or maybe as a smart pointer if polymorphic behavior was needed, and it ...
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187 views

Better application design - where to place interfaces

Where to place interfaces in a typical multi-layered app with DataAccess, BusinessLogic and an Endpoint modules? I propose 2 options In both cases there's only dependency from abstractions, but in ...
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3answers
400 views

Manual Dependency Injection Examples Still Tightly Coupled

I've been using AutoFac for some time now to take care of the dependency injection we're using in a web project. All is well, but I now want to demonstrate DI outside of an AutoFac context for reasons ...
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278 views

Shell commands in bash or python? How much encapsulation is too much?

I'm thinking about how to decide whether it's better to encapsulate my work behind well-named function names, or to expose it - which will help developers understand what's going on more quickly? Is ...
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What does the Spring framework do? Should I use it? Why or why not?

So, I'm starting a brand-new project in Java, and am considering using Spring. Why am I considering Spring? Because lots of people tell me I should use Spring! Seriously, any time I've tried to get ...
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1answer
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For DI, where to create dependencies (new objects) specifically within framework code?

Basic requirement I'm making a framework for learning purposes (and likely usage on personal sites). I'm using dependency injection in classes and I'm trying to design where would be a good place ...
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1answer
260 views

Usage - Factory Pattern vs Dependency Injection [closed]

Okay, this question is not on which is better. It is more about when to use Dependency Injection vs Factory. I have done a bit of research and it goes like this. DIP: Provides loose coupling, ...
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76 views

Inject or not dependencies in a component based framework

I'm currently developing a small component-based framework the Android platform. The framework has some ready for use and some abstract (has some internal logic, but the developer needs to add some ...
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311 views

How to avoid using service location when using dependency injection? [closed]

I am trying to use dependency injection in a WPF application, and I really can't figure how to avoid using service location, which is considered to be an anti-pattern in many articles. I am using the ...
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Dependency injection: At what point am I allowed to create a new object?

I am refactoring a PHP application, and I am trying to do has much dependency injection (DI) as possible. I feel like I've got a good grasp of how it works, and I can certainly see my classes ...
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200 views

Dependency Management in the real world?

Most of the examples i've see when watching anything on dependency management hit what i consider to be the holy grail in that the only dependencies on classes are interfaces that the IOC container ...
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Is the use of a constant as a parameter of an Unit Test mocked dependency's method wrong?

We have a Unit Test Case where we want to assert that after a login operation, the SUT is able to call a method on one of it's dependencies. This dependency is a NavigationManager and the expectation ...
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3k views

Does “Inversion of Control” promote “Anemic Domain Model”?

When I used IoC Container in my last project, I ended up with anemic entities and most of my business logic in Stateless Services. I have seen projects written by other developers that utilize "...
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1answer
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Difference between spring setter and interface injection?

I know how constructor and setter injection works in spring. Normally I use interfaces instead of classes to inject beans using setter and I consider it as interface injection, but in case of ...
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556 views

Pooling (Singleton) Objects Against Connection Pools

Given the following scenario A canned enterprise application that maintains its own connection pool A homegrown client application to the enterprise app. This app is built using Spring framework, ...
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4answers
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Difference between Dependency Injection (DI) and Inversion of Control (IOC)

I've been seeing a lot of references of Dependency Injection (DI) & Inversion Of Control (IOC), but I don't really know if there is a difference between them or not. I would like to start using ...
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1answer
515 views

How should dependencies be managed across a modular application?

Let's say that we have a structure like this: Application -- Modules --Module1 -- Controller -- PublicHelper --Module2 -- Controller ...
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4answers
410 views

Design Pattern for retry and error handling

I'm trying to find a good design pattern, or perhaps series of patterns, for injecting error handling and retry handling when getting data from a webservice. For instance, I have: do { //get the ...
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169 views

How should I refactor a singleton (to be used by a container) when the refactored class requires initialization and takes a dependency?

I'm refactoring an old app to use dependency injection.n I'm pretty new to DI. I have a class that used to be a singleton. I'm refactoring it into a non-singleton class and using the container to ...
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705 views

PHP: Injecting the same database connection into multiple objects

Suppose that there are two classes that define objects of vastly different function such that in the datastore, the information they require is divided into two separate databases. For example, the ...