❔ static fields for struct types

(1)

public static class StructA  
{
   public static readonly StructA  ValueA = new (..) ;
}

or as Utility class

public static class Utility
{
   public static readonly StructA  ValueA = new (..) ;
}

(2)

public static class Utility
{
   private static readonly StructA  _valueA = new (..) ;
   public static StructA ValueA => _valueA;
}

The first and second one are the same but I have seen some libs prefer to implement them like (2)
(3)

public static class Utility
{
   // Initialize every time.
   public static StructA ValueA => new(..);
}

and what is the benefit of implementation (3)

What about defensive copy for readonly structs?

The arrow syntax defines a property. It's almost always preferred to use properties instead of public fields so you can change your implementation later (for instance, add some input validation on set) without it being a breaking change to consumers of your class.

In general, don't expose public fields.

I'm not sure what you mean by defensive copy of readonly structs. Any read of a struct is generally going to make a copy.

The benefit of 3, for simple struct creations, is that you're not taking up space for an unnecessary field

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.