CA1052: Static holder types should be sealed
Note
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| Item | Value |
|---|---|
| TypeName | StaticHolderTypesShouldBeSealed |
| CheckId | CA1052 |
| Category | Microsoft.Design |
| Breaking Change | Breaking |
Cause
A public or protected type contains only static members and is not declared with the sealed (NotInheritable) modifier.
Rule Description
This rule assumes that a type that contains only static members is not designed to be inherited, because the type does not provide any functionality that can be overridden in a derived type. A type that is not meant to be inherited should be marked with the sealed modifier to prohibit its use as a base type.
How to Fix Violations
To fix a violation of this rule, mark the type as sealed. If you are targeting .NET Framework 2.0 or earlier, a better approach is to mark the type as static. In this manner, you avoid having to declare a private constructor to prevent the class from being created.
When to Suppress Warnings
Suppress a warning from this rule only if the type is designed to be inherited. The absence of the sealed modifier suggests that the type is useful as a base type.
Example of a Violation
Description
The following example shows a type that violates the rule.
Code
using namespace System;
namespace DesignLibrary
{
public ref class StaticMembers
{
static int someField;
StaticMembers() {}
public:
static property int SomeProperty
{
int get()
{
return someField;
}
void set(int value)
{
someField = value;
}
}
static void SomeMethod() {}
};
}
using System;
namespace DesignLibrary
{
public class StaticMembers
{
static int someField;
public static int SomeProperty
{
get
{
return someField;
}
set
{
someField = value;
}
}
StaticMembers() {}
public static void SomeMethod() {}
}
}
Imports System
Namespace DesignLibrary
Public Class StaticMembers
Private Shared someField As Integer
Shared Property SomeProperty As Integer
Get
Return someField
End Get
Set
someField = Value
End Set
End Property
Private Sub New()
End Sub
Shared Sub SomeMethod()
End Sub
End Class
End Namespace
Fix with the Static Modifier
Description
The following example shows how to fix a violation of this rule by marking the type with the static modifier.
Code
using System;
namespace DesignLibrary
{
public static class StaticMembers
{
private static int someField;
public static int SomeProperty
{
get { return someField; }
set { someField = value; }
}
public static void SomeMethod()
{
}
public static event SomeDelegate SomeEvent;
}
public delegate void SomeDelegate();
}