parse field type

src/lib.rs

@@ -9,17 +9,32 @@ pub fn id_derive(input: TokenStream) -> TokenStream {
 	// Parse the input tokens into a syntax tree
 	let ast = parse_macro_input!(input as DeriveInput);
 	let name = &ast.ident;
+	let ty = match &ast.data {
+		syn::Data::Struct(s) => {
+			if let syn::Fields::Unnamed(fields) = &s.fields {
+				if fields.unnamed.len() != 1 {
+					return syn::Error::new_spanned(&ast, "Expected exactly one field.").to_compile_error().into();
+				}
+				&fields.unnamed[0].ty
+			} else {
+				return syn::Error::new_spanned(&ast, "Expected a tuple struct.").to_compile_error().into();
+			}
+		}
+		_ => {
+			return syn::Error::new_spanned(&ast, "Expected a struct.").to_compile_error().into();
+		}
+	};
 
 	// Generate the code for the implementation
 	let expanded = quote! {
 		impl #name {
 			#[inline]
-			pub const fn new(id: u32) -> Self {
+			pub const fn new(id: #ty) -> Self {
 				Self(id)
 			}
 
 			#[inline]
-			pub const fn get(self) -> u32 {
+			pub const fn get(self) -> #ty {
 				self.0
 			}
 		}