Revised generate_enum_property_option to be closer to an eventual derive.

dcb/src/game/card/property.rs

@@ -214,9 +214,17 @@ generate_enum_property_mod!(
 );
 
 util::generate_enum_property_option!(
-	pub struct MaybeArrowColor      (ArrowColor      ) => 0,
-	pub struct MaybeCrossMoveEffect (CrossMoveEffect ) => 0,
-	pub struct MaybeDigimonProperty (DigimonProperty ) => 0,
+	#[derive(BytesProxySentinel)]
+	#[bytes_proxy_sentinel(value = 0)]
+	pub struct MaybeArrowColor(Option<ArrowColor>);
+
+	#[derive(BytesProxySentinel)]
+	#[bytes_proxy_sentinel(value = 0)]
+	pub struct MaybeCrossMoveEffect(Option<CrossMoveEffect>);
+
+	#[derive(BytesProxySentinel)]
+	#[bytes_proxy_sentinel(value = 0)]
+	pub struct MaybeDigimonProperty(Option<DigimonProperty>);
 );
 
 // Complex

dcb/src/game/deck.rs

@@ -57,9 +57,17 @@ generate_enum_property_mod! {
 }
 
 generate_enum_property_option!(
-	pub struct MaybeCity    (City    ) => 0,
-	pub struct MaybeArmorEvo(ArmorEvo) => 0,
-	pub struct MaybeMusic   (Music   ) => 0,
+	#[derive(BytesProxySentinel)]
+	#[bytes_proxy_sentinel(value = 0)]
+	pub struct MaybeCity(Option<City>);
+
+	#[derive(BytesProxySentinel)]
+	#[bytes_proxy_sentinel(value = 0)]
+	pub struct MaybeArmorEvo(Option<ArmorEvo>);
+
+	#[derive(BytesProxySentinel)]
+	#[bytes_proxy_sentinel(value = 0)]
+	pub struct MaybeMusic(Option<Music>);
 );
 
 // Modules

dcb/src/util/impl_bytes.rs

@@ -133,47 +133,49 @@ macro_rules! generate_enum_property_mod
 /// is the first argument of this macro and an enum.
 ///
 /// This is done by supplying a sentinel value which is read/written as `None`.
-pub macro generate_enum_property_option {
-	(
-		$( $struct_vis:vis struct $struct_name:ident ( $enum_vis:vis $enum_name:ty ) => $sentinel_value:literal ),* $(,)?
-	) => {
-		$(
-			#[repr(transparent)]
-			#[derive(derive_more::From, derive_more::Into)]
-			$struct_vis struct $struct_name( $enum_vis Option<$enum_name> );
+pub macro generate_enum_property_option (
+	$(
+		#[derive(BytesProxySentinel)]
+		#[bytes_proxy_sentinel(value = $sentinel_value:literal)]
+		$struct_vis:vis struct $struct_name:ident ( $enum_vis:vis Option<$enum_name:ty> );
+	)*
+) {
+	$(
+		#[repr(transparent)]
+		#[derive(derive_more::From, derive_more::Into)]
+		$struct_vis struct $struct_name( $enum_vis Option<$enum_name> );
 
-			impl<'a> From<&'a Option<$enum_name>> for &'a $struct_name {
-				#[allow(clippy::as_conversions)] // We need `as` to make pointer casts
-				fn from(opt: &'a Option<$enum_name>) -> Self {
-					// SAFETY: We're `repr(transparent)`, so this cast is safe
-					unsafe { &*(opt as *const Option<$enum_name> as *const $struct_name) }
+		impl<'a> From<&'a Option<$enum_name>> for &'a $struct_name {
+			#[allow(clippy::as_conversions)] // We need `as` to make pointer casts
+			fn from(opt: &'a Option<$enum_name>) -> Self {
+				// SAFETY: We're `repr(transparent)`, so this cast is safe
+				unsafe { &*(opt as *const Option<$enum_name> as *const $struct_name) }
+			}
+		}
+
+		#[allow(clippy::diverging_sub_expression)] // Errors might be `!`
+		impl ::dcb_bytes::Bytes for $struct_name {
+			type ByteArray = <$enum_name as ::dcb_bytes::Bytes>::ByteArray;
+
+			type FromError = <$enum_name as ::dcb_bytes::Bytes>::FromError;
+			fn from_bytes(bytes: &Self::ByteArray) -> Result<Self, Self::FromError>
+			{
+				match bytes {
+					$sentinel_value => Ok( Self(None) ),
+					_               => Ok( Self(Some( ::dcb_bytes::Bytes::from_bytes(bytes)? )) ),
 				}
 			}
 
-			#[allow(clippy::diverging_sub_expression)] // Errors might be `!`
-			impl ::dcb_bytes::Bytes for $struct_name {
-				type ByteArray = <$enum_name as ::dcb_bytes::Bytes>::ByteArray;
-
-				type FromError = <$enum_name as ::dcb_bytes::Bytes>::FromError;
-				fn from_bytes(bytes: &Self::ByteArray) -> Result<Self, Self::FromError>
-				{
-					match bytes {
-						$sentinel_value => Ok( Self(None) ),
-						_               => Ok( Self(Some( ::dcb_bytes::Bytes::from_bytes(bytes)? )) ),
-					}
+			type ToError = <$enum_name as ::dcb_bytes::Bytes>::ToError;
+			fn to_bytes(&self, bytes: &mut Self::ByteArray) -> Result<(), Self::ToError>
+			{
+				match &self.0 {
+					Some(value) => ::dcb_bytes::Bytes::to_bytes(value, bytes)?,
+					None        => *bytes = $sentinel_value,
 				}
 
-				type ToError = <$enum_name as ::dcb_bytes::Bytes>::ToError;
-				fn to_bytes(&self, bytes: &mut Self::ByteArray) -> Result<(), Self::ToError>
-				{
-					match &self.0 {
-						Some(value) => ::dcb_bytes::Bytes::to_bytes(value, bytes)?,
-						None        => *bytes = $sentinel_value,
-					}
-
-					Ok(())
-				}
+				Ok(())
 			}
-		)*
-	}
+		}
+	)*
 }