Added support for variant-attributes, updated README to show the syntax

README.md

@@ -120,6 +120,34 @@ let mut drink_kinds = HashSet::new();
 drink_kinds.insert(DrinkKind::Mate);
 ```
 
+#### Variant Attributes
+
+Some traits require or allow additional configuration via attributes on variants.
+These can be passed through using `#[kinded(...)]`.
+You can only pass one attribute per `#[kinded(...)]`, though you can use multiple of these attributes per variant.
+
+```rs
+use kinded::Kinded;
+
+#[derive(Kinded)]
+#[kinded(derive(Default, Hash, Default))]
+enum Drink {
+    #[kinded(default)]
+    #[kinded(doc = "Not suitable for small children. Please talk to your IT-person about the harmful effects of mate addiction.")]
+    Mate,
+    #[kinded(doc = "Not suitable for small children!")]
+    Coffee(String),
+    #[kinded(default)]
+    #[kinded(doc = "Only suitable for small children if caffeine-free.")]
+    Tea { variety: String, caffeine: bool }
+}
+
+// Now we can access default without having to implement it ourself.
+// Also the drink kinds now have a small doc!
+let default_drink_kind = DrinkKind::default();
+```
+This can also be used to configure derivations of [`Serialize`](https://docs.rs/serde/latest/serde/trait.Serialize.html) and [`Deserialize`](https://docs.rs/serde/latest/serde/trait.Deserialize.html) of [`serde`](https://docs.rs/serde/latest/serde/index.html) or 
+[`EnumMessage`](https://docs.rs/strum/latest/strum/trait.EnumMessage.html) from [`strum`](https://docs.rs/strum/latest/strum/) via `#[kinded(strum(message = "Important message"))]`
 ### Display trait
 
 Implementation of `Display` trait can be customized in the `serde` fashion:

kinded_macros/src/generate/kind_enum.rs

@@ -22,12 +22,18 @@ fn gen_definition(meta: &Meta) -> TokenStream {
     let vis = &meta.vis;
     let kind_name = meta.kind_name();
     let variant_names: Vec<&Ident> = meta.variants.iter().map(|v| &v.ident).collect();
+    let variant_attr: Vec<&[TokenStream]> = meta
+        .variants
+        .iter()
+        .map(|v| v.kinded_variant_attrs.as_slice())
+        .collect();
     let traits = meta.derive_traits();
 
     quote!(
-        #[derive(#(#traits),*)]                                                // #[derive(Debug, Clone, Copy, PartialEq, Eq)]
+        #[derive(#(#traits),*)]                                                // #[derive(Default, Debug, Clone, Copy, PartialEq, Eq)]
         #vis enum #kind_name {                                                 // pub enum DrinkKind {
-            #(#variant_names),*                                                //     Mate, Coffee, Tea
+            #( #(#[#variant_attr])*                                            //
+            #variant_names),*                                                  //     Mate, Coffee, #[default] Tea
         }                                                                      // }
 
         impl #kind_name {                                                      // impl DrinkKind {

kinded_macros/src/models.rs

@@ -61,6 +61,10 @@ impl Meta {
 pub struct Variant {
     pub ident: Ident,
     pub fields_type: FieldsType,
+    /// Attributes specified with `#[kinded(CONTENT)]` above the variants of the original enum.
+    /// The token streams in here only contain the `CONTENT` from the example above.
+    /// These can be pasted as is into the kind enum.
+    pub kinded_variant_attrs: Vec<TokenStream>,
 }
 
 /// This mimics syn::Fields, but without payload.

kinded_macros/src/parse.rs

@@ -38,6 +38,7 @@ fn parse_variant(variant: &syn::Variant) -> Variant {
     Variant {
         ident: variant.ident.clone(),
         fields_type: parse_fields_type(&variant.fields),
+        kinded_variant_attrs: parse_kinded_variant_attrs(&variant),
     }
 }
 
@@ -49,6 +50,30 @@ fn parse_fields_type(fields: &syn::Fields) -> FieldsType {
     }
 }
 
+/// This function takes a variant and returns a vector of token stream.
+/// The token streams were previously the content of a `#[kinded(...)]` attribute on this variant.
+/// Other attributes are ignored as they are (probably) meant for the main enum.
+///
+/// Multiple `#[kinded(...)]` attributes can be present on one variant, therefore a vector will collect them.
+fn parse_kinded_variant_attrs(variant: &'_ syn::Variant) -> Vec<proc_macro2::TokenStream> {
+    variant
+        .attrs
+        .iter()
+        .filter_map(|attr| {
+            // Only keep attributes of the form `path(...)`
+            match &attr.meta {
+                syn::Meta::List(meta_list) => Some(meta_list),
+                _ => None,
+            }
+        })
+        .filter_map(|meta_list|
+        // and only if the path is "kinded"
+        // then will probably save a teeny tiny amount of time
+        // as it skips the cloning in cases were the path does not match.
+        meta_list.path.is_ident("kinded").then(|| meta_list.tokens.clone()))
+        .collect()
+}
+
 /// Find `#[kinded(..)]` attribute on the enum.
 fn find_kinded_attr(input: &DeriveInput) -> Result<Option<&Attribute>, syn::Error> {
     let kinded_attrs: Vec<_> = input

test_suite/Cargo.toml

@@ -7,3 +7,4 @@ edition = "2024"
 
 [dependencies]
 kinded = {  path = "../kinded" }
+strum = { version = "0.27.2", features = ["derive"] }

test_suite/src/lib.rs

@@ -5,6 +5,56 @@
 extern crate alloc;
 
 use kinded::Kinded;
+mod variant_attributes {
+    //! This test module uses the [`EnumMessage`]-Trait because if variant attributes do not work,
+    //! the derive-macro will still finish successfully.
+    //! The corresponding methods will just return `None`.
+
+    use super::*;
+    use alloc::string::String;
+    use strum::EnumMessage;
+
+    #[derive(Kinded)]
+    #[kinded(derive(Hash, Default, EnumMessage))]
+    enum Drink {
+        #[kinded(doc = "Not suitable for small children. Please talk to your IT-person about the harmful effects of mate addiction.")]
+        #[kinded(strum(
+            message = "Made from fermented leaves.",
+            detailed_message="Caffeinated beverage from South America. Not suitable for small children because of caffeine."
+        ))]
+        Mate,
+        #[kinded(doc = "Not suitable for small children!")]
+        #[kinded(strum(
+            message = "Made from roasted, ground beans.",
+            detailed_message="Beverage made from roasted, ground beans that originated somewhere around the read sea. Not suitable for small children, especially Espresso."
+        ))]
+        Coffee(String),
+        #[kinded(default)]
+        #[kinded(doc = "Only suitable for small children if caffeine-free.")]
+        #[kinded(strum(
+            message = "Made from fermented leaves.",
+            detailed_message="Beverage made from fermented leaves that originated from china. Some contain caffeine and are not suitable for small children."
+        ))]
+        Tea { variety: String, caffeine: bool }
+    }
+    #[test]
+    pub fn test_message() {
+        let mate = DrinkKind::Mate;
+        assert_eq!(Some("Made from fermented leaves."), mate.get_message());
+        assert_eq!(Some("Caffeinated beverage from South America. Not suitable for small children because of caffeine."), mate.get_detailed_message());
+        assert_eq!(Some("Not suitable for small children. Please talk to your IT-person about the harmful effects of mate addiction."), mate.get_documentation());
+
+        let coffee = DrinkKind::Coffee;
+        assert_eq!(Some("Made from roasted, ground beans."), coffee.get_message());
+        assert_eq!(Some("Beverage made from roasted, ground beans that originated somewhere around the read sea. Not suitable for small children, especially Espresso."), coffee.get_detailed_message());
+        assert_eq!(Some("Not suitable for small children!"), coffee.get_documentation());
+
+        let tea = DrinkKind::Tea;
+        assert_eq!(Some("Made from fermented leaves."), tea.get_message());
+        assert_eq!(Some("Beverage made from fermented leaves that originated from china. Some contain caffeine and are not suitable for small children."), tea.get_detailed_message());
+        assert_eq!(Some("Only suitable for small children if caffeine-free."), tea.get_documentation());
+    }
+}
 
 #[derive(Kinded)]
 enum Role {