add docs for law::new_desc

src/law/mod.rs

@@ -347,7 +347,54 @@ impl Builder {
         }
     }
 
-    /// Sets a new description for the last classifier.
+    /// Sets a new description for the last classifier in the law structure.
+    ///
+    /// This method updates the description of the most recently added classifier. It's useful for
+    /// providing additional context or details about the classifier's role or content within the
+    /// law's hierarchy.
+    ///
+    /// # Parameters
+    ///
+    /// - `desc`: A string slice representing the new description to be assigned to the last
+    /// classifier. The description is trimmed of any leading or trailing whitespace before being
+    /// set.
+    ///
+    /// # Behavior
+    ///
+    /// - The method trims the input description. - It then attempts to update the description of
+    /// the last classifier. If no classifier has been added before this method is called, the
+    /// function will panic, indicating that setting a description requires a preceding classifier
+    /// to be in place.
+    ///
+    /// # Panics
+    ///
+    /// Panics if there is no last classifier available when the method is called. This situation
+    /// occurs if an attempt is made to set a description of a classifier before any classifier has
+    /// been added to the structure, highlighting a logical error in the usage sequence.
+    ///
+    /// # Examples
+    /// ```
+    /// use risp::{config::Config, law::{Law, Heading}};
+    /// use std::path::Path;
+    ///
+    /// let (_, mut builder, _) = Config::load(Path::new("data/configs/abgb.toml")).unwrap();
+    ///
+    /// builder.new_header("1. Theil");
+    /// builder.new_desc("Description of the first header");
+    ///
+    /// let law: Law = builder.into();
+    /// assert_eq!(
+    ///     law,
+    ///     Law {
+    ///         name: "ABGB".into(),
+    ///         header: vec![Heading {
+    ///             name: "1. Theil".into(),
+    ///             desc: Some("Description of the first header".into()),
+    ///             content: vec![]
+    ///         }]
+    ///     }
+    /// );
+    /// ```
     pub fn new_desc(&mut self, desc: &str) {
         let desc = desc.trim();
         #[cfg(test)]
@@ -356,7 +403,7 @@ impl Builder {
         debug!("new_desc={desc}");
         self.last_instance
             .clone()
-            .unwrap()
+            .expect("We can only set a description, if we already have received a classifier.")
             .borrow_mut()
             .set_desc(desc);
     }