rspec/rules/S4039/csharp/rule.adoc

== Why is this an issue?

When a base type explicitly implements a public interface method, property or event, that member is only accessible in derived types through a reference to the current instance (namely `this`). If the derived type explicitly overrides that interface member, the base implementation becomes inaccessible.

This rule raises an issue when an unsealed, externally visible type provides an explicit member implementation of an `interface` and does not provide an alternate, externally visible member with the same name.

=== Exceptions

This rule does not report a violation for an explicit implementation of `IDisposable.Dispose` when an externally visible `Close()` or `System.IDisposable.Dispose(Boolean)` method is provided.

== How to fix it

Make the class sealed, change the class member to a non-explicit declaration, or provide a new class member exposing the functionality of the explicit interface member.

=== Code examples

==== Noncompliant code example

[source,csharp,diff-id=1,diff-type=noncompliant]
----
public interface IMyInterface
{
    void MyMethod();
}

public class Foo : IMyInterface
{
    void IMyInterface.MyMethod() // Noncompliant
    {
        MyMethod();
    }
}
----


==== Compliant solution

[source,csharp,diff-id=1,diff-type=compliant]
----
public interface IMyInterface
{
    void MyMethod();
}

public class Foo : IMyInterface
{
    void IMyInterface.MyMethod()
    {
        MyMethod();
    }

    // This method can be public or protected
    protected void MyMethod()
    {
        // Do something ...
    }
}
----

== Resources

=== Documentation

* Microsoft Learn - https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/interfaces/explicit-interface-implementation[Explicit Interface Implementation]

ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

=== Message

Make "XXX" sealed, change to a non explicit declaration or provide a new method exposing the functionality of "YYY".


=== Highlighting

Explicit interface method implementation


endif::env-github,rspecator-view[]