Additional mapping parameters for derived mappings

[danielwinkler]

The documentation clearly indicates the limitation of Additional mapping parameters for derived mappings

I would like to ask if you would consider a strict way where you would support it; e.g. you would copy the exact signature to the generated derived type mappings.

Example Mapper

using Riok.Mapperly.Abstractions;

namespace Medel.ReDi.Backend.UnitTests.Mappers;

public class MyBaseClass
{
    public int x;
    public double y;
    public string z;
}

public class MyDerivedDateClass : MyBaseClass
{
    public DateTime a;
}

public class MyDerivedGuidClass : MyBaseClass
{
    public Guid b;
}

public class MyBaseClassDTO
{
    public int x;
    public double y;
    public string z;
    public DateTime RetrievedAt;
}

public class MyDerivedDateClassDTO : MyBaseClassDTO
{
    public DateTime a;
}

public class MyDerivedGuidClassDTO : MyBaseClassDTO
{
    public Guid b;
}

[Mapper]
public static partial class MyMapper
{
    [MapDerivedType<MyDerivedDateClass, MyDerivedDateClassDTO>]
    [MapDerivedType<MyDerivedGuidClass, MyDerivedGuidClassDTO>]
    public static partial MyBaseClassDTO Map(MyBaseClass source, DateTime retrievedAt);
}

Generated Output

// <auto-generated />
#nullable enable
namespace Medel.ReDi.Backend.UnitTests.Mappers
{
    public static partial class MyMapper
    {
        [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "4.3.0.0")]
        public static partial global::Medel.ReDi.Backend.UnitTests.Mappers.MyBaseClassDTO Map(global::Medel.ReDi.Backend.UnitTests.Mappers.MyBaseClass source, global::System.DateTime retrievedAt)
        {
            return source switch
            {
                global::Medel.ReDi.Backend.UnitTests.Mappers.MyDerivedDateClass x => MapToMyDerivedDateClassDTO(x),
                global::Medel.ReDi.Backend.UnitTests.Mappers.MyDerivedGuidClass x => MapToMyDerivedGuidClassDTO(x),
                _ => throw new global::System.ArgumentException($"Cannot map {source.GetType()} to Medel.ReDi.Backend.UnitTests.Mappers.MyBaseClassDTO as there is no known derived type mapping", nameof(source)),
            };
        }

        [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "4.3.0.0")]
        private static global::Medel.ReDi.Backend.UnitTests.Mappers.MyDerivedDateClassDTO MapToMyDerivedDateClassDTO(global::Medel.ReDi.Backend.UnitTests.Mappers.MyDerivedDateClass source)
        {
            var target = new global::Medel.ReDi.Backend.UnitTests.Mappers.MyDerivedDateClassDTO();
            target.a = source.a;
            target.x = source.x;
            target.y = source.y;
            target.z = source.z;
            target.RetrievedAt = retrievedAt;
            return target;
        }

        [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "4.3.0.0")]
        private static global::Medel.ReDi.Backend.UnitTests.Mappers.MyDerivedGuidClassDTO MapToMyDerivedGuidClassDTO(global::Medel.ReDi.Backend.UnitTests.Mappers.MyDerivedGuidClass source)
        {
            var target = new global::Medel.ReDi.Backend.UnitTests.Mappers.MyDerivedGuidClassDTO();
            target.b = source.b;
            target.x = source.x;
            target.y = source.y;
            target.z = source.z;
            target.RetrievedAt = retrievedAt;
            return target;
        }
    }
}

If the generated functions would be extended by , global::System.DateTime retrievedAt then the generated mappings would work.