CA1715: Identifiers should have correct prefix

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For the latest documentation on Visual Studio, see CA1715: Identifiers should have correct prefix.

TypeName IdentifiersShouldHaveCorrectPrefix
CheckId CA1715
Category Microsoft.Naming
Breaking Change Breaking - when fired on interfaces.

Non-breaking - when raised on generic type parameters.

Cause

The name of an externally visible interface does not start with an uppercase 'I'.

-or-

The name of a generic type parameter on an externally visible type or method does not start with an uppercase 'T'.

Rule Description

By convention, the names of certain programming elements start with a specific prefix.

Interface names should start with an uppercase 'I' followed by another uppercase letter. This rule reports violations for interface names such as 'MyInterface' and 'IsolatedInterface'.

Generic type parameter names should start with an uppercase 'T' and optionally may be followed by another uppercase letter. This rule reports violations for generic type parameter names such as 'V' and 'Type'.

Naming conventions provide a common look for libraries that target the common language runtime. This reduces the learning curve that is required for new software libraries, and increases customer confidence that the library was developed by someone who has expertise in developing managed code.

How to Fix Violations

Rename the identifier so that it is correctly prefixed.

When to Suppress Warnings

Do not suppress a warning from this rule.

Example

The following example shows an incorrectly named interface.

using namespace System;

namespace Samples
{
    public interface class Book     // Violates this rule
    {
        property String^ Title
        {
            String^ get();
        }
        void Read();
    };
}
using System;

namespace Samples
{
    public interface Book   // Violates this rule
    {
        string Title
        {
            get;
        }

        void Read();        
    }
}
Imports System

Namespace Samples

    Public Interface Book      ' Violates this rule

        ReadOnly Property Title() As String

        Sub Read()

    End Interface

End Namespace

Example

The following example fixes the previous violation by prefixing the interface with 'I'.

using namespace System;

namespace Samples
{
    public interface class IBook  // Fixes the violation by prefixing the interface with 'I'
    {
        property String^ Title
        {
            String^ get();
        }
        void Read();
    };
}
using System;

namespace Samples
{
    public interface IBook      // Fixes the violation by prefixing the interface with 'I'
    {
        string Title
        {
            get;
        }

        void Read();        
    }
}
Imports System

Namespace Samples

    Public Interface IBook  ' Fixes the violation by prefixing the interface with 'I'

        ReadOnly Property Title() As String

        Sub Read()

    End Interface

End Namespace

Example

The following example shows an incorrectly named generic type parameter.

using namespace System;

namespace Samples
{
    generic <typename Item>     // Violates this rule
    public ref class Collection
    {

    };
}
using System;

namespace Samples
{
    public class Collection<Item>   // Violates this rule
    {

    }
}
Imports System

Namespace Samples

    Public Class Collection(Of Item)    ' Violates this rule

    End Class

End Namespace

Example

The following example fixes the previous violation by prefixing the generic type parameter with 'T'.

using namespace System;

namespace Samples
{
    generic <typename TItem>  // Fixes the violation by prefixing the generic type parameter with 'T'
    public ref class Collection
    {

    };
}
using System;

namespace Samples
{
    public class Collection<TItem>  // Fixes the violation by prefixing the generic type parameter with 'T'

    {

    }
}
Imports System

Namespace Samples

    Public Class Collection(Of TItem)  ' Fixes the violation by prefixing the generic type parameter with 'T'

    End Class

End Namespace

CA1722: Identifiers should not have incorrect prefix