ExportAs Attribute for Godot CSharp Projects.

ExportAsAttribute.cs

using System.Linq;
using Godot;
using Godot.Collections;

namespace Vial.Export {

  [System.AttributeUsage(System.AttributeTargets.Property, Inherited = false, AllowMultiple = true)]
  public sealed class ExportAsAttribute : System.Attribute {

    internal readonly string _name;
    internal readonly int _type;
    internal readonly int? _hint;
    internal readonly string? _hintString;

    public ExportAsAttribute( string name, Variant.Type type ) : this( name, type, null, null, null ) {}
    public ExportAsAttribute( string name, Variant.Type type, PropertyHint hint ) : this(name, type, hint, null, null) {}
    public ExportAsAttribute( string name, Variant.Type type, PropertyHint hint, string hintString ) : this (name, type, hint, hintString, null) {}
    private ExportAsAttribute( string name, Variant.Type type, PropertyHint? hint, string? hintString, int? trigger ) {
      _name = name;
      _type = (int)type;
      _hint = (int?)hint;
      _hintString = hintString;
    }

    public Dictionary ToDict() {
      var dict = new Dictionary(){ {"name", _name}, {"type", _type} };
      if (_hint != null)  dict.Add( "hint", _hint );
      if (_hintString != null)  dict.Add( "hint_string", _hintString );
      return dict;
    }

  }

  public static class ExportExt{

    public static Dictionary[] GetPropertyListFromAttributes<T>( this T o ) where T : Object {
      return typeof(T)
        .GetProperties()
        .Where( p => System.Attribute.IsDefined(p, typeof(ExportAsAttribute)) )
        .SelectMany( p => p
          .GetCustomAttributes( true )
          .OfType<ExportAsAttribute>()
        )
        .Select( p => p.ToDict() )
        .ToArray();
    }

    public static bool TryToSetPropertyWithAttribute<T>( this T o, string propertyStr, object value) where T : Object {
      try {
        var propertyInfo = typeof(T)
          .GetProperties()
          .Where( p => System.Attribute.IsDefined(p, typeof(ExportAsAttribute)) )
          .FirstOrDefault( p => p
            .GetCustomAttributes(true)
            .Any( a => (a is ExportAsAttribute eaa) && eaa._name == propertyStr )
          );
        if ( propertyInfo == null )  return false;
        propertyInfo.SetValue(o, value, System.Reflection.BindingFlags.SetProperty, null, null, null);
        return true;
      }
      catch ( System.Exception e ) {
        System.Console.WriteLine( $"Could not set property with attribute {e} {e.StackTrace}" );
        return false;
      }
    }

    public static object? TryToGetPropertyWithAttribute<T>( this T o, string propertyStr ) where T : Object {
      try {
        var propertyInfo = typeof(T)
          .GetProperties()
          .Where( p => System.Attribute.IsDefined(p, typeof(ExportAsAttribute)) )
          .FirstOrDefault( p => p
            .GetCustomAttributes(true)
            .Any( a => (a is ExportAsAttribute eaa) && eaa._name == propertyStr )
          );
        if ( propertyInfo == null )  return null;
        return propertyInfo.GetValue(o, System.Reflection.BindingFlags.GetProperty, null, null, null);
      }
      catch ( System.Exception e ) {
        System.Console.WriteLine( $"Could not get property with attribute {e} {e.StackTrace}" );
        return null;
      }
    }

  }

}


// EXAMPLE USAGE:

//    [ExportAs("display/style", Variant.Type.Object, PropertyHint.ResourceType, "StyleBox")]
//    public StyleBox? Style {
//      get => _style;
//      set {
//        _style = value;
//        _updatePadding();  QueueSort();
//      }
//    }
//    private StyleBox? _style;
//
//    // NOTE: you will want to wrap code in a try-catch right now.
//    //       [Tool] mode will crash on exceptions otherwise.
//    public override Godot.Collections.Array _GetPropertyList() {
//      try {
//        return new Godot.Collections.Array( this.GetPropertyListFromAttributes() );
//      } catch ( Exception e ) {
//        System.Console.WriteLine( $"[{nameof(MyClass)}] _GetPropertyList Exception: {e}\n{e.StackTrace}" );
//        throw;
//      }
//    }
//
//    public override bool _Set(string propertyStr, object value) {
//      try {
//        return this.TryToSetPropertyWithAttribute( propertyStr, value );
//      } catch ( Exception e ) {
//        Console.WriteLine( $"[{nameof(MyClass)}] _Set Exception: {e}\n{e.StackTrace}" );
//        return false;
//      }
//    }
//
//    public override object? _Get(string propertyStr) {
//      try {
//        return this.TryToGetPropertyWithAttribute( propertyStr );
//      } catch ( Exception e ) {
//        Console.WriteLine( $"[{nameof(MyClass)}] _Get Exception: {e}\n{e.StackTrace}" );
//        return null;
//      }
//    }