107 lines
2.9 KiB
Plaintext
107 lines
2.9 KiB
Plaintext
== Why is this an issue?
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Decreasing the https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/classes-and-structs/access-modifiers[accessibility level] of an inherited method that is not https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/override[overridable] to https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/private[private] will shadow the name of the base method and can lead to confusion.
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[source,csharp]
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----
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public class Base
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{
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public void SomeMethod(int count) { }
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}
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public class Derived : Base
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{
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private void SomeMethod(int count) { } // Noncompliant
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}
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class Program
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{
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public void DoWork()
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{
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var derived = new Derived();
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derived.SomeMethod(42); // Base.SomeMethod is accessed here
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}
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}
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----
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Another potential problem is the case of a class deriving from `Derived` and accessing `SomeMethod`. In this scenario, the method accessed will instead be the `Base` implementation, which might not be what was expected.
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[source,csharp]
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----
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public class Base
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{
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public void SomeMethod(int count) { }
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}
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public class Derived : Base
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{
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private void SomeMethod(int count) { } // Noncompliant
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}
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public class SecondDerived : Derived
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{
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public void DoWork()
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{
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SomeMethod(42); // Base.SomeMethod is accessed here
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}
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}
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----
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One way to mitigate this, is by sealing the `Derived` class by using the https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/sealed[sealed] modifier, thus preventing inheritance from this point on.
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[source,csharp]
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----
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public class Base
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{
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public void SomeMethod(int count) { }
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}
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public sealed class Derived : Base
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{
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private void SomeMethod(int count) { } // Compliant: class is marked as sealed
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}
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----
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Another way to mitigate this, is by having the `Derived` implementation match the https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/classes-and-structs/access-modifiers[accessibility] modifier of the `Base` implementation of `SomeMethod`. From a caller's perspective, this is closer to the expected behavior.
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[source,csharp]
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----
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using System;
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namespace MyLibrary
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{
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public class Base
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{
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public void SomeMethod(int count) { }
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}
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public class Derived : Base
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{
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public void SomeMethod(int count) { } // Compliant: same accessibility as Base.SomeMethod
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}
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public class Program
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{
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public void DoWork()
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{
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var derived = new Derived();
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derived.SomeMethod(42); // Derived.SomeMethod is called
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}
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}
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}
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----
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Last but not least, consider using a different name for the `Derived` method, thus completely eliminating any confusion caused by the naming collision.
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[source,csharp]
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----
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public class Base
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{
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public void SomeMethod(int count) { }
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}
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public class Derived : Base
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{
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private void SomeOtherMethod(int count) { } // Compliant
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}
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----
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include::../resources.adoc[]
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include::../rspecator.adoc[]
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