dependency injection
Dependency injection is basically providing the objects that an object needs
(its dependencies) instead of having it construct them itself.
It's a very useful technique for testing, since it allows dependencies
to be mocked or stubbed out.dependency injection
Class A Class B if A uses some methods of B then its a dependency injectiondependency injection
class User
{
private $database = null;
public function __construct(Database $database) {
$this->database = $database;
}
public function getUsers() {
return $this->database->getAll('users');
}
}
$database = new Database('host', 'user', 'pass', 'dbname');
$user = new User($database);
$user->getUsers();dependency injection
public class CustomerService
{
CustomerBusinessLogic _customerBL;
public CustomerService()
{
_customerBL = new CustomerBusinessLogic(new CustomerDataAccess());
}
public string GetCustomerName(int id) {
return _customerBL.ProcessCustomerData(id);
}
}dependency injection
public class CustomerBusinessLogic
{
ICustomerDataAccess _dataAccess;
public CustomerBusinessLogic(ICustomerDataAccess custDataAccess)
{
_dataAccess = custDataAccess;
}
public CustomerBusinessLogic()
{
_dataAccess = new CustomerDataAccess();
}
public string ProcessCustomerData(int id)
{
return _dataAccess.GetCustomerName(id);
}
}
public interface ICustomerDataAccess
{
string GetCustomerName(int id);
}
public class CustomerDataAccess: ICustomerDataAccess
{
public CustomerDataAccess()
{
}
public string GetCustomerName(int id)
{
//get the customer name from the db in real application
return "Dummy Customer Name";
}
}Dependency Injection .net
using System;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.Hosting;
namespace DependencyInjection.Example
{
public class Worker : BackgroundService
{
private readonly IMessageWriter _messageWriter;
public Worker(IMessageWriter messageWriter) =>
_messageWriter = messageWriter;
protected override async Task ExecuteAsync(CancellationToken stoppingToken)
{
while (!stoppingToken.IsCancellationRequested)
{
_messageWriter.Write($"Worker running at: {DateTimeOffset.Now}");
await Task.Delay(1000, stoppingToken);
}
}
}
}Copyright © 2021 Codeinu
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