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16 Feb 2024

Intermediate

In .NET Core, a circular dependency or circular reference exception occurs when two or more classes or components depend on each other directly or indirectly in a cyclic manner. This creates a situation where resolving dependencies becomes impossible due to the circular nature of their relationships.

Let's illustrate this with a simple example:

// Class A depends on Class B
public class ClassA
{
    private readonly ClassB _classB;

    public ClassA(ClassB classB)
    {
        _classB = classB;
    }

    public void DoSomething()
    {
        Console.WriteLine("Doing something in Class A");
        _classB.DoSomethingElse();
    }
}

// Class B depends on Class A
public class ClassB
{
    private readonly ClassA _classA;

    public ClassB(ClassA classA)
    {
        _classA = classA;
    }

    public void DoSomethingElse()
    {
        Console.WriteLine("Doing something else in Class B");
        _classA.DoSomething(); // This creates a circular dependency
    }
}

class Program
{
    static void Main(string[] args)
    {
        // Creating instances of ClassA and ClassB
        ClassA classA = new ClassA(new ClassB(null));
        ClassB classB = new ClassB(classA);

        // Calling methods
        classA.DoSomething();
        classB.DoSomethingElse();
    }
}

In this example, ClassA depends on ClassB, and ClassB depends on ClassA. When an instance of ClassA calls the DoSomething() method, it in turn calls the DoSomethingElse() method of ClassB. However, the DoSomethingElse() method of ClassB calls back the DoSomething() method of ClassA, creating a circular dependency.

When you try to run this code, it will lead to a stack overflow exception or an infinite loop because the methods keep calling each other recursively.

Circular dependencies like this can arise due to poor design or architecture of the application. To avoid such issues, it's essential to refactor the code to break the circular dependency. This can often involve restructuring the classes, introducing interfaces, or utilizing design patterns such as dependency injection to decouple the classes and improve the overall design of the application.

Read More: 👉 How to avoid circular dependencies or circular reference exceptions in C# .NET Core?

c-sharp
.net-core
varun
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