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CA1813: Avoid unsealed attributes

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Property Value
Rule ID CA1813
Title Avoid unsealed attributes
Category Performance
Fix is breaking or non-breaking Breaking
Enabled by default in .NET 8 No

Cause

A public type inherits from System.Attribute, is not abstract, and is not sealed (NotInheritable in Visual Basic).

Rule description

.NET provides methods for retrieving custom attributes. By default, these methods search the attribute inheritance hierarchy. For example, System.Attribute.GetCustomAttribute searches for the specified attribute type or any attribute type that extends the specified attribute type. Sealing the attribute eliminates the search through the inheritance hierarchy, and can improve performance.

How to fix violations

To fix a violation of this rule, seal the attribute type or make it abstract.

When to suppress warnings

It is safe to suppress a warning from this rule. Suppress only if you are defining an attribute hierarchy and cannot seal the attribute or make it abstract.

Suppress a warning

If you just want to suppress a single violation, add preprocessor directives to your source file to disable and then re-enable the rule.

#pragma warning disable CA1813
// The code that's violating the rule is on this line.
#pragma warning restore CA1813

To disable the rule for a file, folder, or project, set its severity to none in the configuration file.

[*.{cs,vb}]
dotnet_diagnostic.CA1813.severity = none

For more information, see How to suppress code analysis warnings.

Example

The following example shows a custom attribute that satisfies this rule.

// Satisfies rule: AvoidUnsealedAttributes.
[AttributeUsage(AttributeTargets.Class | AttributeTargets.Struct)]
public sealed class DeveloperAttribute : Attribute
{
    private string nameValue;
    public DeveloperAttribute(string name)
    {
        nameValue = name;
    }

    public string Name
    {
        get
        {
            return nameValue;
        }
    }
}

Imports System

Namespace ca1813

    ' Satisfies rule: AvoidUnsealedAttributes.
    <AttributeUsage(AttributeTargets.Class Or AttributeTargets.Struct)>
    Public NotInheritable Class DeveloperAttribute
        Inherits Attribute

        Public Sub New(name As String)
            Me.Name = name
        End Sub


        Public ReadOnly Property Name() As String
    End Class

End Namespace

See also