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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How to properly handle conditional dependencies in a factory?

Let's say you have a string $action run-time, that specifies which type of $object needs to be created: $dbobject, $memcacheobject, $fileobject, $xmlobject, etc. Assume also, that creation of an ...
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How to handle passing multiple dependencies in a module hierarchy

So I have my application consisting of a number of modules in a module hierarchy. Furthermore let's also assume each module is a class and we have a tree of classes where the classes at the top are ...
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229 views

Applying DDD to a simple app with a configuration twist

I’m using the light-weight PHP Fat-Free Framework as a base to form a simple MVC based app with DDD philosophy for the Model layer. I’m aware that DDD is most suitable or enterprise solutions and that ...
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Using 2 Constructors: one that injects dependencies and one that instantiates them

I started using TDD for the first time on a project I started recently. I have a few objects with dependencies and structures that look something like this: public class MyClass { private ...
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How to extend Constructor Injection?

Suppose I have MyClass with a very simple dependency. It uses constructor injection. public class MyClass : IMyClass { private IA A; public MyClass(IA a) { A = a; } } This ...
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Where should I put bindings for dependency injection?

I'm new to dependency injection and though I've really liked it so far, I'm not sure where bindings should go. I'm using Guice in Java, so some of what I say might be specific to just Guice. As I see ...
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489 views

To Repository Or Not To Repository

When I first learnt about Domain Driven Design, I was also introduced to the repository and unit of work patterns that once seemed to be top notch for the cool kids that threw SQL queries like ...
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108 views

Dependency injection for request variables in a web application

I'm working a PHP 5.5/MySQL web application. If a class depends partly on some global GET and POST variables for its members, should I just refer to them directly from within the class, or should I ...
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Spring bean injection into a hibernate validator constraint

I have a controller method like listed below whose argument is annotated with @Valid to validate PasswordChange object using a Hibernate validator @Constraint. Both PasswordChange and a sample ...
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How to design a domain entity that uses a dependency to manage a state field?

I'm new to DDD and IOC/DI and I'm having some trouble figuring out how to design an entity that needs to use a state pattern to manage its status. As the transitions are somewhat complicated, I'm ...
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295 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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471 views

Organising data access for dependency injection

In our company we have a relatively long history of database backed applications, but have only just begun experimenting with dependency injection. I am looking for advice about how to convert our ...
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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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State Pattern Code for embedded device - Dependency Injection of Device Objects in Context and State Classes

I'm wrestling with some code and I think I've finally gotten some state pattern code working with my events. I've got a simplified system that will work like this: This is my first go with State ...
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Dependency Injection vs Mixing Levels of Abstraction

I've been reading Clean Code: A Handbook of Agile Software Craftsmanship by Robert C. Martin. One point he makes: G34 Functions should descend only one level of abstraction However, I'm ...
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Initialization of objects in a system using dependency injection

This is a follow up question to the following post: Injecting dependencies (DI) in c++ applications In a system that uses DI, someone, somewhere should be responsible to create the various objects ...
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Injecting dependencies (DI) in c++ applications

I am playing with dependency injection, but i am not sure I am doing it right. Especially, I am not sure what should be the correct way to build classes with injected dependencies. Say I have a class ...
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Logging page/session ID in an inner module

We have a C# ORM module that generates queries. It logs generated queries and other information into the error/trace file. It is used by our web application. Most of our queries are generated ...
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314 views

Does Serialization preclude the use of Dependency Injection?

Simple question: I understand that Serialization in C# requires default constructors. This would eliminate the possibility of using Constructor injected DI (which is generally the favored style of DI, ...
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Unit testing, factories, and the Law of Demeter

Here's how my code works. I have an object that represents the current state of something akin to a shopping cart order, stored in a 3rd party shopping API. In my controller code, I want to be able to ...
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Understanding dependency injection

I'm reading about dependency injection (DI). To me, it is a very complicated thing to do, as I was reading it was referencing inversion of control (IoC) as well and such I felt I was going to be in ...
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Manual dependency injection or abstract factory

We're starting to use dependency injection in a fairly large, interactive program. It's early yet, but I have a feeling that the majority of the objects being injected are going to want runtime data ...
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How to decouple simple factory and default implementation?

I have a simple factory class (FileResources) with static factory methods providing a default implementation (DefaultFileResource). public final class FileResources { private FileResources() {} ...
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Which classes should be autowired by Spring (when to use dependency injection)?

I have been using Dependency Injection in Spring for some time now, and I understand how it works and what are some pros and cons of using it. However, when I'm creating a new class I often wonder - ...
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Application settings via constructor injection or ambient context

I am developing an application containing a class which loads application settings from a configuration file. Settings class: public sealed class MyAppSettings : IMyAppSettings { private ...
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Should I consider loosely-coupling for class methods as well? [duplicate]

I'm a fan of Dependency Injection, however I don't know how much both public and private methods inside a class should be loosely-coupled. Just to picture it better, when I have both projectId and ...
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Help With Dependency Injection

I am still very confused as to why and when to use Dependency Injection. If anyone could explain maybe using the below example that would be great, any other explanations would be appreciated. Lets ...
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Practical Use of Depency Injection (IoC) Container

I am creating a MVC-ish framework in PHP. I am trying to implement a DI Container to allow the creation of controller objects (among others). My MVC framework is pretty typical. Each module (or ...
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What is the clean way to pass my LoginContext down through the layers to the data access layer?

I have inherited an API implemented using ASP.NET WebApi 2. The actions on the controllers are all like this: public object Get(long id) { LoginContext loginDetails = GetLoginDetails(); if ...
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253 views

DI or Factory Pattern ? Both ? or a different apprach?

Lets say we have an abstract class called BaseSwitch, inherited by concrete implementations Switch A and Switch B, Each Switch representing a real-life switch (A telephony tool which among its ...
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132 views

Reducing Coupling in a Series of Tasks

I am working on some code right now that involves processing user requests. Each request requires going through an approval. When a request is made, one or more records are created on the database ...
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849 views

Should IoC container be part of portable library?

I am seeing the benefits of Portable Class Libraries for centralizing Models and ViewModels to a single code-base. Where should dependency injection management (IoC container) take place, though? My ...
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What am I missing in my (mis)understanding of IoC/DI/Castle Windsor?

Okay, so here's how I understand IoC and DI in Web API to work when using Castle Windsor. Note, though, that my confidence that I understand it as I should, though, falls somewhere between my ...
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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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Loose coupling and shuffling dependencies

I have a bunch of classes that look something like this: public class MyGame() { private Graphics graphics; private Player player; public MyGame() { graphics = new ...
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Can I use Dependency Injection without breaking Encapsulation?

Here is my Solution and projects: BookStore (solution) BookStore.Coupler (project) Bootstrapper.cs BookStore.Domain (project) CreateBookCommandValidator.cs CompositeValidator.cs IValidate.cs ...
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Loading data for ShoppingCart item

I'm currently trying to cover our shopping cart with unit tests. Class ShoppingCartItem has property Term. It also loads available terms for this item upon object creation. Currently this is done ...
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257 views

How to refactor out static members of basic classes

Currently I am working on C++ project, which can be classified as "legacy" project. A lot of poor written code was committed because of lack of experience and under the pressure of deadlines. When I ...
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Factory Pattern and/or Dependency Injection?

I understand the concept and can use both the Factory Pattern and Dependency Injection, however they seem a little at odds with each other conceptually. Is it a case of using one over the other? Or ...
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High Level Configuration of Constructor Injection in C++

My questions are specifically dealing with dependency injection through the constructor. I understand the pros/cons of service locator pattern, constructor/setter injection, and their flavors, however ...
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What does Dependency Injection mean by saying it can inject on runtime?

I understand that the dependency injection is something done by coding and its all done at compile time. And that Dependency injection coding is easily done now by helper tools like Ninject. However ...
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Why does the modifier access for the properties need to be public with Unity?

Why does the modifier access for the properties need to be public with Unity? I'm very interested in a detailed explanation for my question. I read about tips to do it in other ways, but not a ...
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it is a good approach to implement dependency injection in a desktop app?

Well, the thing is that I am just about to create a Desktop App (with .NET windows forms) And now I just wonder if it would be really a wise choise to use any IoC (StructureMap,Ninject,Spring .Net), ...
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Can Dependency Injection used as an alternative to Reflection for creating instances

There is a piece of .net C# code which use Reflection to create an instance using Activator.CreateInstance(). This is an old piece of code and runs on the top of Enterprise Library. Is it a better ...
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168 views

Service layer coupling

I am working on writing a service layer for an order system in php. It's the typical scenario, you have an Order that can have multiple Line Items. So lets say a request is received to store a line ...
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MVVM and service pattern

I'm building a WPF application using the MVVM pattern. Right now, my viewmodels calls the service layer to retrieve models (how is not relevant to the viewmodel) and convert them to viewmodels. I'm ...
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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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2answers
599 views

Dependency injection with Finite State Machines and the Interface Segregation Principle

I am trying to figure out what is the best way to setup a FSM and also keep my interfaces clean and use an IOC container to use DI. Let's just visit the Head First design pattern textbook example of ...
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74 views

Inject specific classes or not

I have a TableSqlBuilder interface which has a method getCreateTableSql. This interface is used in some other class as follows: function createTable( $tableDefinition ) { $sql = ...
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The Nature of Spring [duplicate]

Is it accurate to say that dependency injection manually using java (without spring) is nothing but implementing the strategy pattern (as per this example)? Furthermore, is it correct to say that ...