Enforcing nameof Usage with [MandatoryNameof] Attribute

[2Xpro-pop]

I’d like to discuss a proposal for a new attribute called [MandatoryNameof], aimed at enhancing code safety and readability. This attribute ensures the use of nameof for method parameters, reducing the reliance on magic strings.

The Proposal

Introduce [MandatoryNameof], an attribute to enforce compile-time checks for nameof usage:

[AttributeUsage(AttributeTargets.Parameter)]
public class MandatoryNameofAttribute : Attribute
{
    public MandatoryNameofTarget Target { get; set; } = MandatoryNameofTarget.All;
    public Type? Type { get; set; } = null;

    public MandatoryNameofAttribute() { }
}

How It Works

• Target: Specifies the type of code elements (e.g., Property, Method, Event, Field, or Type) that the nameof should reference. All is the default, allowing any type.
• Type: (Optional) When set, restricts the nameof reference to members of the specified type, enhancing type safety.

Example Use Case

public void RegisterEventHandler([MandatoryNameof(Target = MandatoryNameofTarget.Event, Type = typeof(MyEvents))] string eventName)
{
    // Event handler registration logic
}

This enforces that eventName must be the name of an event defined in the MyEvents class.

[CyrusNajmabadi]

This does not need any language change. It is already possible for you to create such an attribute today and then check it with an analyzer you write :-)

This is a core example of the type of scenario analyzers set out to provide a solution for :-)