Allow frontend to pass arguments to Lua callback functions

for compatibility w/ older versions: `event.can_use_callback_params ~= nil`

src/BizHawk.Client.Common/lua/INamedLuaFunction.cs

@@ -6,7 +6,7 @@ namespace BizHawk.Client.Common
 {
 	public interface INamedLuaFunction
 	{
-		Action Callback { get; }
+		Action InputCallback { get; }
 
 		Guid Guid { get; }
 

src/BizHawk.Client.Common/lua/LuaFunctionList.cs

@@ -28,7 +28,7 @@ namespace BizHawk.Client.Common
 		{
 			if (emulator.InputCallbacksAvailable())
 			{
-				emulator.AsInputPollable().InputCallbacks.Remove(function.Callback);
+				emulator.AsInputPollable().InputCallbacks.Remove(function.InputCallback);
 			}
 
 			if (emulator.MemoryCallbacksAvailable())
@@ -64,7 +64,7 @@ namespace BizHawk.Client.Common
 		{
 			if (emulator.InputCallbacksAvailable())
 			{
-				emulator.AsInputPollable().InputCallbacks.RemoveAll(_functions.Select(w => w.Callback));
+				emulator.AsInputPollable().InputCallbacks.RemoveAll(_functions.Select(w => w.InputCallback));
 			}
 
 			if (emulator.MemoryCallbacksAvailable())

src/BizHawk.Client.Common/lua/LuaHelperLibs/EventsLuaLibrary.cs

@@ -44,6 +44,10 @@ namespace BizHawk.Client.Common
 			Log($"{scope} is not an available scope for {Emulator.Attributes().CoreName}");
 		}
 
+		[LuaMethod("can_use_callback_params", "Returns true. Check this function exists to decide whether to use hacks for older versions w/o parameter support.")]
+		[LuaMethodExample("local mem_callback = event.can_use_callback_params ~= nil and mem_callback or mem_callback_pre_28;")]
+		public bool CanUseCallbackParams()
+			=> true;
 
 		[LuaMethodExample("local steveonf = event.onframeend(\r\n\tfunction()\r\n\t\tconsole.log( \"Calls the given lua function at the end of each frame, after all emulation and drawing has completed. Note: this is the default behavior of lua scripts\" );\r\n\tend\r\n\t, \"Frame name\" );")]
 		[LuaMethod("onframeend", "Calls the given lua function at the end of each frame, after all emulation and drawing has completed. Note: this is the default behavior of lua scripts")]
@@ -68,7 +72,7 @@ namespace BizHawk.Client.Common
 			{
 				try
 				{
-					InputPollableCore.InputCallbacks.Add(nlf.Callback);
+					InputPollableCore.InputCallbacks.Add(nlf.InputCallback);
 					return nlf.Guid.ToString();
 				}
 				catch (NotImplementedException)

src/BizHawk.Client.Common/lua/NamedLuaFunction.cs

@@ -32,19 +32,19 @@ namespace BizHawk.Client.Common
 
 			Guid = Guid.NewGuid();
 
-			Callback = () =>
+			Callback = args =>
 			{
 				try
 				{
-					_function.Call();
+					_function.Call(args);
 				}
 				catch (Exception ex)
 				{
 					logCallback($"error running function attached by the event {Event}\nError message: {ex.Message}");
 				}
 			};
-
+			InputCallback = () => Callback(Array.Empty<object>());
-			MemCallback = (address, value, flags) => Callback();
+			MemCallback = (addr, val, flags) => Callback(new object[] { addr, val, flags });
 		}
 
 		public void DetachFromScript()
@@ -66,7 +66,9 @@ namespace BizHawk.Client.Common
 
 		public string Event { get; }
 
-		public Action Callback { get; }
+		private Action<object[]> Callback { get; }
+
+		public Action InputCallback { get; }
 
 		public MemoryCallbackDelegate MemCallback { get; }