use error-chain for errors

Cargo.toml

@@ -4,7 +4,8 @@ version = "0.1.0"
 authors = ["Felix Döring <[email protected]>", "Felix Wittwer <[email protected]>"]
 
 [dependencies]
+json = "0.11.6"
 serde = "0.9.5"
 serde_json = "0.9.4"
 serde_derive = "0.9.5"
-json = "0.11.6"
+error-chain = "0.10.0"

src/error.rs

@@ -1,98 +1,68 @@
 //! Custom Error Types for errors that may occur when handling todos (or lists).
 
-use std::error::Error;
-use std::fmt;
-use std::convert::From;
-
 /// Custom Result Type for tdo.
 ///
 /// This abbreviation is introduced since many functions throughout the crate return
 /// this type of result, which bundles all possible errors of the `tdo_core` crate.
-pub type TdoResult<T> = Result<T, ErrorKind>;
-
-/// Enum to collect all types of tdo errors.
-///
-/// This is simply a wrapper for all custom error classes the `tdo_crate` has.
-#[derive(Clone, Copy, Debug)]
-pub enum ErrorKind {
-    /// A storage-related error occured while interacting with the file system.
-    StorageError(StorageError),
-    /// An error within the tdo data structures occured.
-    TodoError(TodoError),
-}
-
-/// The Errors that may occur while interacting with the file system.
-#[derive(Clone, Copy, Debug)]
-pub enum StorageError {
-    /// The accessed file is corrupted. This is most likely
-    /// because someone edited the JSON file manually.
-    FileCorrupted,
-    /// The conversion of an older format failed.
-    UnableToConvert,
-    /// The data could not be written to the file.
-    SaveFailure,
-    /// The requested file could not be found.
-    FileNotFound,
-}
-
-impl fmt::Display for StorageError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "{}", self.description())
-    }
-}
+pub type TdoResult<T> = Result<T>;
 
-impl Error for StorageError {
-    fn description(&self) -> &str {
-        match *self {
-            StorageError::FileCorrupted => "File is corrupted",
-            StorageError::SaveFailure => "File could not be saved",
-            StorageError::FileNotFound => "File was not found",
-            StorageError::UnableToConvert => "File could not be converted automatically",
-        }
-    }
-}
-
-impl From<StorageError> for ErrorKind {
-    fn from(e: StorageError) -> Self {
-        ErrorKind::StorageError(e)
-    }
-}
 
 /// Errors that can arise when working with todo lists.
-#[derive(Clone, Copy, Debug)]
-pub enum TodoError {
-    /// The requested item is not in the list.
-    NotInList,
-    /// The requested todo list does not exist.
-    NoSuchList,
-    /// The default list is tried to be removed.
-    CanNotRemoveDefault,
-    /// A list with the same name already exists.
-    NameAlreadyExists,
-    /// A todo with the same ID already exists.
-    IDAlreadyExists,
-}
-
-impl fmt::Display for TodoError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "{}", self.description())
+pub mod todo_error {
+    error_chain! {
+        errors {
+            /// The requested item is not in the list.
+            NotInList {
+                description("Todo is not in this list")
+            }
+            /// The requested todo list does not exist.
+            NoSuchList {
+                description("No such list")
+            }
+            /// The default list is tried to be removed.
+            CanNotRemoveDefault {
+                description("The default list can no be removed")
+            }
+            /// A list with the same name already exists.
+            NameAlreadyExists {
+                description("There already exists a list with this name")
+            }
+            /// A todo with the same ID already exists.
+            IDAlreadyExists {
+                description("There already exists a todo with this ID")
+            }
+        }
     }
 }
 
-impl Error for TodoError {
-    fn description(&self) -> &str {
-        match *self {
-            TodoError::NotInList => "Todo is not in this list",
-            TodoError::NoSuchList => "No such list",
-            TodoError::CanNotRemoveDefault => "The default list can no be removed",
-            TodoError::NameAlreadyExists => "There already exists a list with this name",
-            TodoError::IDAlreadyExists => "There already exists a todo with this ID",
+/// The Errors that may occur while interacting with the file system.
+pub mod storage_error {
+    error_chain! {
+        errors {
+            /// The accessed file is corrupted. This is most likely
+            /// because someone edited the JSON file manually.
+            FileCorrupted {
+                description("File is corrupted")
+            }
+            /// The data could not be written to the file.
+            SaveFailure {
+                description("File could not be saved")
+            }
+            /// The requested file could not be found.
+            FileNotFound {
+                description("File was not found")
+            }
+            /// The conversion of an older format failed.
+            UnableToConvert {
+                description("File could not be converted automatically")
+            }
         }
     }
 }
 
-impl From<TodoError> for ErrorKind {
-    fn from(e: TodoError) -> Self {
-        ErrorKind::TodoError(e)
+error_chain! {
+    links {
+        TodoError(todo_error::Error, todo_error::ErrorKind) #[doc = "An error within the tdo data structures occured."];
+        StorageError(storage_error::Error, storage_error::ErrorKind) #[doc = "A storage-related error occured while interacting with the file system."];
     }
 }

src/lib.rs

@@ -4,8 +4,8 @@
         trivial_casts, trivial_numeric_casts,
         unused_import_braces, unused_qualifications)]
 #![warn(missing_debug_implementations)]
-#[macro_use]
-extern crate serde_derive;
+#[macro_use] extern crate serde_derive;
+#[macro_use] extern crate error_chain;
 extern crate serde_json;
 extern crate json;
 

src/list.rs

@@ -52,7 +52,7 @@ impl TodoList {
     pub fn contains_id(&self, id:u32) -> TdoResult<usize> {
         match self.list.iter().position(|x| x.id == id) {
             Some(index) => Ok(index),
-            None => Err(TodoError::NotInList.into()),
+            None => Err(ErrorKind::TodoError(todo_error::ErrorKind::NotInList).into()),
         }
     }
     /// Mark a todo from the list with the given ID as done.
@@ -62,7 +62,7 @@ impl TodoList {
     pub fn done_id(&mut self, id: u32) -> TdoResult<()> {
         match self.contains_id(id) {
             Ok(index) => Ok(self.list[index].set_done()),
-            _ => Err(TodoError::NotInList.into()),
+            _ => Err(ErrorKind::TodoError(todo_error::ErrorKind::NotInList).into()),
         }
     }
 
@@ -73,7 +73,7 @@ impl TodoList {
     pub fn remove_id(&mut self, id: u32) -> TdoResult<Todo> {
         match self.contains_id(id) {
             Ok(index) => Ok(self.list.remove(index)),
-            _ => Err(TodoError::NotInList.into()),
+            _ => Err(ErrorKind::TodoError(todo_error::ErrorKind::NotInList).into()),
         }
     }
 

src/tdo.rs

@@ -57,7 +57,7 @@ impl Tdo {
                     Err(_) => update_json(path),
                 }
             }
-            Err(_) => Err(StorageError::FileNotFound.into()),
+            Err(_) => Err(ErrorKind::StorageError(storage_error::ErrorKind::FileNotFound).into()),
         }
 
     }
@@ -84,14 +84,14 @@ impl Tdo {
                 let _ = super::serde_json::to_writer_pretty(&mut f, self);
                 Ok(())
             }
-            Err(_) => Err(StorageError::SaveFailure.into()),
+            Err(_) => Err(ErrorKind::StorageError(storage_error::ErrorKind::SaveFailure).into()),
         }
     }
 
     /// Add a todo list to the container.
     pub fn add_list(&mut self, list: TodoList) -> TdoResult<()> {
         match self.get_list_index(&list.name) {
-            Ok(_) => Err(TodoError::NameAlreadyExists.into()),
+            Ok(_) => Err(ErrorKind::TodoError(todo_error::ErrorKind::NameAlreadyExists).into()),
             Err(_) => {
                 self.lists.push(list);
                 Ok(())
@@ -102,14 +102,14 @@ impl Tdo {
     /// Removes a list from the container.
     pub fn remove_list(&mut self, list_name: &str) -> TdoResult<()> {
         if list_name == "default" {
-            Err(TodoError::CanNotRemoveDefault.into())
+            Err(ErrorKind::TodoError(todo_error::ErrorKind::CanNotRemoveDefault).into())
         } else {
             match self.get_list_index(list_name) {
                 Ok(index) => {
                     self.lists.remove(index);
                     Ok(())
                 }
-                Err(_) => Err(TodoError::NoSuchList.into()),
+                Err(_) => Err(ErrorKind::TodoError(todo_error::ErrorKind::NoSuchList).into()),
             }
         }
     }
@@ -138,7 +138,7 @@ impl Tdo {
                 return Ok(list);
             }
         }
-        Err(TodoError::NotInList.into())
+        Err(ErrorKind::TodoError(todo_error::ErrorKind::NotInList).into())
     }
     /// Cycle through all todo lists and mark a todo with the given ID as done.
     /// This function has no return value and thus won't indicate whether
@@ -177,7 +177,7 @@ impl Tdo {
             .iter()
             .position(|x| x.name.to_lowercase() == name.to_string().to_lowercase()) {
             Some(index) => Ok(index),
-            None => Err(TodoError::NoSuchList.into()),
+            None => Err(ErrorKind::TodoError(todo_error::ErrorKind::NoSuchList).into()),
         }
     }
 
@@ -196,7 +196,7 @@ fn update_json(path: &str) -> TdoResult<Tdo> {
     file.read_to_string(&mut data).unwrap();
     let mut json = match parse(&data) {
         Ok(content) => content,
-        Err(_) => return Err(StorageError::FileCorrupted.into()),
+        Err(_) => return Err(ErrorKind::StorageError(storage_error::ErrorKind::FileCorrupted).into()),
     };
 
     let mut lists: Vec<TodoList> = vec![];
@@ -206,15 +206,15 @@ fn update_json(path: &str) -> TdoResult<Tdo> {
         for inner in outer.1.entries_mut() {
             let tdo_id = match inner.0.parse::<u32>() {
                 Ok(id) => id,
-                Err(_) => return Err(StorageError::UnableToConvert.into()),
+                Err(_) => return Err(ErrorKind::StorageError(storage_error::ErrorKind::UnableToConvert).into()),
             };
             let done = match inner.1.pop().as_bool() {
                 Some(x) => x,
-                None => return Err(StorageError::UnableToConvert.into()),
+                None => return Err(ErrorKind::StorageError(storage_error::ErrorKind::UnableToConvert).into()),
             };
             let tdo_name = match inner.1.pop().as_str() {
                 Some(x) => String::from(x),
-                None => return Err(StorageError::UnableToConvert.into()),
+                None => return Err(ErrorKind::StorageError(storage_error::ErrorKind::UnableToConvert).into()),
             };
             let mut todo = Todo::new(tdo_id, &tdo_name);
             if done {