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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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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538 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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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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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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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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89 views

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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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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274 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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188 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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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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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 ...
2
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1answer
134 views

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 ...
2
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1answer
273 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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1answer
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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2answers
315 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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1answer
201 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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3answers
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How to use Guice for an effective API Design?

I am creating a base API in JavaSE, which includes modules like MVP architecture, Service & Repository Layer, Event Model to fire events between presenter etc. I am trying to implement all best ...
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3answers
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 ...
2
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4answers
414 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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1answer
714 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 ...
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216 views

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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2answers
301 views

Dependency injection of ViewModel with unmanaged parameter

I have a PersonEditViewModel which needs two other objects, the personId and the PersonRepository. PersonRepository is obtained from a service locator: private final int personId; public ...
2
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1answer
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Injection, strategies and OO

I'm working on refactoring a project. The business logic looks very much like using the Strategy pattern would be very beneficial, because depending on the values of three properties (let's say age, ...
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1answer
444 views

C# Dependency Injection with Adapter Pattern

In the following code sample, I have a client that works through a controller. In my specific case the controller establishes a session to an address on a GPIB bus. An instance of this is then ...
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1answer
296 views

How to deal with dependency when you have separate projects?

I know there is all this talk about having only one composition root that set all your dependencies and that you should always prefer constructor injection to other types, but sometimes it just doesn'...
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Share service instances amongst all controllers?

We've taken over coding on a .NET MVC project, and as I'm relatively inexperienced with many of the MVC design approaches, I'm working on getting a good understanding of the design choices. One ...
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1answer
832 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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1answer
60 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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251 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 ...
3
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5answers
303 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 ...
3
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2answers
779 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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2answers
299 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
616 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 ...
2
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1answer
193 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 ...
10
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4answers
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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 ...
2
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1answer
98 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
282 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 ...
0
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1answer
164 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 'inc/...
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2answers
201 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 ...
0
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0answers
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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 ...
5
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2answers
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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
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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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7answers
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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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1answer
219 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 List<...
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1answer
428 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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0answers
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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
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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 ...