Parsing

Vogen 'hoists' (copies up to the wrapper) certain functionality from the underlying primitive. For instance, any method named Parse or TryParse from the underlying primitive is hoisted.

The IParsable family of interfaces (including ISpanParsable and IUtf8SpanParsable) that are implemented publicly by the primitive are hoisted to the wrapper, and the generic parameter is changed to that of the wrapper. The methods that are generated delegate back to the underlying implementation of primitive.

Some primitive types, such as bool, explicitly implement ISpanParsable<bool> privately, so the interface is not hoisted to wrapper, but the non-explicit methods are hoisted.

TryParse calls the underlying's TryParse. It then sees if the parsed value passes the Validate method. If it doesn't, then it will return false, and the out will have a default instance; for classes, a null value, or, for structs, a default value object that will throw if you try to access its value.

strings are a special case. It is useful to have a Parse/TryParse methods on these, for instance, when value objects represent parameters in ASP.NET Core endpoints.

If IParsable<> is not available, e.g., in versions before .NET 7, then the interfaces are not generated for the wrapper. For strings, the Parse and TryParse methods are still generated though.