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How to implement the dependency injection pattern in C#
Educative Answers TeamAny code in which a class depends explicitly on another class is a highly-coupled code. The dependency injection pattern, like other design patterns, aims to lower the coupling (dependency) in a program so that it is easily extendable.
Parts of the pattern
The dependency injection pattern has four main roles which are performed by separate classes:
- Service: Service classes are those which are frequently used by another class. For example, the class
Carwill use the classesWheelandInteriorevery time. - Consumer: The consumer class consumes services; it is also known as a client.
- Interface: This is the interface that is implemented by every service. Introducing this interface reduces dependency between a consumer and the services it utilizes. Moreover, it increases the flexibility of our code.
- Injector: The main class which instantiates a service and injects it into the consumer.
UML diagram
Implementation
using System;
// Service interface:
interface IService{
string getName();
}
// First implementation of IService:
class SlowService: IService{
private string name = "Slow service";
public string getName(){
return name;
}
}
// Second implementation of IService:
class FastService: IService{
private string name = "Fast service";
public string getName(){
return name;
}
}
// Consumer class:
class Consumer{
private IService myService;
public Consumer(IService s){
myService = s;
}
public IService getService(){
return myService;
}
}
// Injector/Main class:
class Injector{
static void Main(string[] args){
Consumer x = new Consumer(new SlowService());
Console.WriteLine(x.getService().getName());
Consumer y = new Consumer(new FastService());
Console.WriteLine(y.getService().getName());
}
}RELATED TAGS
dependency
injection
design
pattern
solid
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