Support parameter-less event methods in `DataContractSerializer` (without a `StreamingContext` parameter)

[Takym]

When I use event methods for the DataContractSerializer system, I still need a StreamingContext parameter even though the BinaryFormatter stuff is deprecated. The constructor and state property of StreamingContext is marked as obsolete.

The StreamingContext _ parameter is unused in the below code. I feel it is redundant.

[OnSerializing()]
void OnSerializing(StreamingContext _) { ... }

[OnSerialized()]
void OnSerializing(StreamingContext _) { ... }

[OnDeserializing()]
void OnSerializing(StreamingContext _) { ... }

[OnDeserialized()]
void OnSerializing(StreamingContext _) { ... }

Parameter-less one like the code below makes me feel refreshed. Also, we do not need to type unused parameters. So, developing efficiency is more improved. In addition, maybe, passing (copying structure data) the parameter makes a program slow. Or maybe, the speed is the same because of checking parameters.

[OnSerializing()]
void OnSerializing() { ... }

[OnSerialized()]
void OnSerializing() { ... }

[OnDeserializing()]
void OnSerializing() { ... }

[OnDeserialized()]
void OnSerializing() { ... }

I agree that we should still support with StreamingContext _ parameter for compatibility but I want a parameter-less option.

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[Takym]

Related codes

runtime/src/libraries/System.Private.DataContractSerialization/src/System/Runtime/Serialization/ClassDataContract.cs

Lines 1063 to 1142 in f1332ab

	internal void EnsureMethodsImported()
	{
	if (!_isMethodChecked && UnderlyingType != null)
	{
	lock (this)
	{
	if (!_isMethodChecked)
	{
	Type type = UnderlyingType;
	MethodInfo[] methods = type.GetMethods(BindingFlags.DeclaredOnly | BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
	for (int i = 0; i < methods.Length; i++)
	{
	MethodInfo method = methods[i];
	Type? prevAttributeType = null;
	ParameterInfo[] parameters = method.GetParameters();
	if (HasExtensionData && IsValidExtensionDataSetMethod(method, parameters))
	{
	if (method.Name == Globals.ExtensionDataSetExplicitMethod || !method.IsPublic)
	_extensionDataSetMethod = XmlFormatGeneratorStatics.ExtensionDataSetExplicitMethodInfo;
	else
	_extensionDataSetMethod = method;
	}
	if (IsValidCallback(method, parameters, Globals.TypeOfOnSerializingAttribute, _onSerializing, ref prevAttributeType))
	_onSerializing = method;
	if (IsValidCallback(method, parameters, Globals.TypeOfOnSerializedAttribute, _onSerialized, ref prevAttributeType))
	_onSerialized = method;
	if (IsValidCallback(method, parameters, Globals.TypeOfOnDeserializingAttribute, _onDeserializing, ref prevAttributeType))
	_onDeserializing = method;
	if (IsValidCallback(method, parameters, Globals.TypeOfOnDeserializedAttribute, _onDeserialized, ref prevAttributeType))
	_onDeserialized = method;
	}
	Interlocked.MemoryBarrier();
	_isMethodChecked = true;
	}
	}
	}
	}
	private bool IsValidExtensionDataSetMethod(MethodInfo method, ParameterInfo[] parameters)
	{
	if (method.Name == Globals.ExtensionDataSetExplicitMethod || method.Name == Globals.ExtensionDataSetMethod)
	{
	Debug.Assert(method.DeclaringType != null);
	if (_extensionDataSetMethod != null)
	ThrowInvalidDataContractException(SR.Format(SR.DuplicateExtensionDataSetMethod, method, _extensionDataSetMethod, DataContract.GetClrTypeFullName(method.DeclaringType)));
	if (method.ReturnType != Globals.TypeOfVoid)
	DataContract.ThrowInvalidDataContractException(SR.Format(SR.ExtensionDataSetMustReturnVoid, DataContract.GetClrTypeFullName(method.DeclaringType), method), method.DeclaringType);
	if (parameters == null || parameters.Length != 1 || parameters[0].ParameterType != Globals.TypeOfExtensionDataObject)
	DataContract.ThrowInvalidDataContractException(SR.Format(SR.ExtensionDataSetParameterInvalid, DataContract.GetClrTypeFullName(method.DeclaringType), method, Globals.TypeOfExtensionDataObject), method.DeclaringType);
	return true;
	}
	return false;
	}
	private static bool IsValidCallback(MethodInfo method, ParameterInfo[] parameters, Type attributeType, MethodInfo? currentCallback, ref Type? prevAttributeType)
	{
	if (method.IsDefined(attributeType, false))
	{
	Debug.Assert(method.DeclaringType != null);
	if (currentCallback != null)
	DataContract.ThrowInvalidDataContractException(SR.Format(SR.DuplicateCallback, method, currentCallback, DataContract.GetClrTypeFullName(method.DeclaringType), attributeType), method.DeclaringType);
	else if (prevAttributeType != null)
	DataContract.ThrowInvalidDataContractException(SR.Format(SR.DuplicateAttribute, prevAttributeType, attributeType, DataContract.GetClrTypeFullName(method.DeclaringType), method), method.DeclaringType);
	else if (method.IsVirtual)
	DataContract.ThrowInvalidDataContractException(SR.Format(SR.CallbacksCannotBeVirtualMethods, method, DataContract.GetClrTypeFullName(method.DeclaringType), attributeType), method.DeclaringType);
	else
	{
	if (method.ReturnType != Globals.TypeOfVoid)
	DataContract.ThrowInvalidDataContractException(SR.Format(SR.CallbackMustReturnVoid, DataContract.GetClrTypeFullName(method.DeclaringType), method), method.DeclaringType);
	if (parameters == null || parameters.Length != 1 || parameters[0].ParameterType != Globals.TypeOfStreamingContext)
	DataContract.ThrowInvalidDataContractException(SR.Format(SR.CallbackParameterInvalid, DataContract.GetClrTypeFullName(method.DeclaringType), method, Globals.TypeOfStreamingContext), method.DeclaringType);
	prevAttributeType = attributeType;
	}
	return true;
	}
	return false;
	}

runtime/src/libraries/System.Private.DataContractSerialization/src/System/Runtime/Serialization/ReflectionClassWriter.cs

Lines 130 to 150 in f1332ab

	private static void InvokeOnSerializing(object obj, XmlObjectSerializerWriteContext context, ClassDataContract classContract)
	{
	if (classContract.BaseClassContract != null)
	InvokeOnSerializing(obj, context, classContract.BaseClassContract);
	if (classContract.OnSerializing != null)
	{
	var contextArg = context.GetStreamingContext();
	classContract.OnSerializing.Invoke(obj, new object[] { contextArg });
	}
	}
	private static void InvokeOnSerialized(object obj, XmlObjectSerializerWriteContext context, ClassDataContract classContract)
	{
	if (classContract.BaseClassContract != null)
	InvokeOnSerialized(obj, context, classContract.BaseClassContract);
	if (classContract.OnSerialized != null)
	{
	var contextArg = context.GetStreamingContext();
	classContract.OnSerialized.Invoke(obj, new object[] { contextArg });
	}
	}

runtime/src/libraries/System.Private.DataContractSerialization/src/System/Runtime/Serialization/Json/JsonFormatWriterGenerator.cs

Lines 174 to 198 in f1332ab

	private void InvokeOnSerializing(ClassDataContract classContract)
	{
	if (classContract.BaseClassContract != null)
	InvokeOnSerializing(classContract.BaseClassContract);
	if (classContract.OnSerializing != null)
	{
	_ilg.LoadAddress(_objectLocal);
	_ilg.Load(_contextArg);
	_ilg.Call(XmlFormatGeneratorStatics.GetStreamingContextMethod);
	_ilg.Call(classContract.OnSerializing);
	}
	}
	private void InvokeOnSerialized(ClassDataContract classContract)
	{
	if (classContract.BaseClassContract != null)
	InvokeOnSerialized(classContract.BaseClassContract);
	if (classContract.OnSerialized != null)
	{
	_ilg.LoadAddress(_objectLocal);
	_ilg.Load(_contextArg);
	_ilg.Call(XmlFormatGeneratorStatics.GetStreamingContextMethod);
	_ilg.Call(classContract.OnSerialized);
	}
	}

runtime/src/libraries/System.Private.DataContractSerialization/src/System/Runtime/Serialization/XmlFormatWriterGenerator.cs

Lines 207 to 231 in f1332ab

	private void InvokeOnSerializing(ClassDataContract classContract)
	{
	if (classContract.BaseClassContract != null)
	InvokeOnSerializing(classContract.BaseClassContract);
	if (classContract.OnSerializing != null)
	{
	_ilg.LoadAddress(_objectLocal);
	_ilg.Load(_contextArg);
	_ilg.Call(XmlFormatGeneratorStatics.GetStreamingContextMethod);
	_ilg.Call(classContract.OnSerializing);
	}
	}
	private void InvokeOnSerialized(ClassDataContract classContract)
	{
	if (classContract.BaseClassContract != null)
	InvokeOnSerialized(classContract.BaseClassContract);
	if (classContract.OnSerialized != null)
	{
	_ilg.LoadAddress(_objectLocal);
	_ilg.Load(_contextArg);
	_ilg.Call(XmlFormatGeneratorStatics.GetStreamingContextMethod);
	_ilg.Call(classContract.OnSerialized);
	}
	}

runtime/src/libraries/System.Private.DataContractSerialization/src/System/Runtime/Serialization/ReflectionReader.cs

Lines 398 to 418 in f1332ab

	private static void InvokeOnDeserializing(XmlObjectSerializerReadContext context, ClassDataContract classContract, object obj)
	{
	if (classContract.BaseClassContract != null)
	InvokeOnDeserializing(context, classContract.BaseClassContract, obj);
	if (classContract.OnDeserializing != null)
	{
	var contextArg = context.GetStreamingContext();
	classContract.OnDeserializing.Invoke(obj, new object[] { contextArg });
	}
	}
	private static void InvokeOnDeserialized(XmlObjectSerializerReadContext context, ClassDataContract classContract, object obj)
	{
	if (classContract.BaseClassContract != null)
	InvokeOnDeserialized(context, classContract.BaseClassContract, obj);
	if (classContract.OnDeserialized != null)
	{
	var contextArg = context.GetStreamingContext();
	classContract.OnDeserialized.Invoke(obj, new object[] { contextArg });
	}
	}

runtime/src/libraries/System.Private.DataContractSerialization/src/System/Runtime/Serialization/XmlFormatReaderGenerator.cs

Lines 290 to 322 in f1332ab

	private void InvokeOnDeserializing(ClassDataContract classContract)
	{
	Debug.Assert(_objectLocal != null);
	Debug.Assert(_objectType != null);
	if (classContract.BaseClassContract != null)
	InvokeOnDeserializing(classContract.BaseClassContract);
	if (classContract.OnDeserializing != null)
	{
	_ilg.LoadAddress(_objectLocal);
	_ilg.ConvertAddress(_objectLocal.LocalType, _objectType);
	_ilg.Load(_contextArg);
	_ilg.LoadMember(XmlFormatGeneratorStatics.GetStreamingContextMethod);
	_ilg.Call(classContract.OnDeserializing);
	}
	}
	private void InvokeOnDeserialized(ClassDataContract classContract)
	{
	Debug.Assert(_objectLocal != null);
	Debug.Assert(_objectType != null);
	if (classContract.BaseClassContract != null)
	InvokeOnDeserialized(classContract.BaseClassContract);
	if (classContract.OnDeserialized != null)
	{
	_ilg.LoadAddress(_objectLocal);
	_ilg.ConvertAddress(_objectLocal.LocalType, _objectType);
	_ilg.Load(_contextArg);
	_ilg.LoadMember(XmlFormatGeneratorStatics.GetStreamingContextMethod);
	_ilg.Call(classContract.OnDeserialized);
	}
	}

runtime/src/libraries/System.Private.DataContractSerialization/src/System/Runtime/Serialization/Json/JsonFormatReaderGenerator.cs

Lines 232 to 258 in f1332ab

	private void InvokeOnDeserializing(ClassDataContract classContract)
	{
	if (classContract.BaseClassContract != null)
	InvokeOnDeserializing(classContract.BaseClassContract);
	if (classContract.OnDeserializing != null)
	{
	_ilg.LoadAddress(_objectLocal);
	_ilg.ConvertAddress(_objectLocal.LocalType, _objectType!);
	_ilg.Load(_contextArg);
	_ilg.LoadMember(XmlFormatGeneratorStatics.GetStreamingContextMethod);
	_ilg.Call(classContract.OnDeserializing);
	}
	}
	private void InvokeOnDeserialized(ClassDataContract classContract)
	{
	if (classContract.BaseClassContract != null)
	InvokeOnDeserialized(classContract.BaseClassContract);
	if (classContract.OnDeserialized != null)
	{
	_ilg.LoadAddress(_objectLocal);
	_ilg.ConvertAddress(_objectLocal.LocalType, _objectType!);
	_ilg.Load(_contextArg);
	_ilg.LoadMember(XmlFormatGeneratorStatics.GetStreamingContextMethod);
	_ilg.Call(classContract.OnDeserialized);
	}
	}

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