Rewrite examples/db_remember.rs to use ErasedStorage

CHANGELOG.md

@@ -8,8 +8,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
-- The `Storage::erase` default function that returns `ErasedStorage`.
+- The `Storage::erase` default function that returns `Arc<ErasedStorage>`.
 - `ErasedStorage`, a storage with an erased error type.
+- Allow the storage generic `S` be `?Sized` in `Dialogue`.
 
 ## 0.7.1 - 2022-03-09
 

examples/db_remember.rs

@@ -1,12 +1,23 @@
-use teloxide::{macros::DialogueState, prelude2::*, types::Me, utils::command::BotCommand};
+// Set the `DB_REMEMBER_REDIS` environmental variable if you want to use Redis.
+// Otherwise, the default is Sqlite.
 
-// include!("redis_config.in");
-include!("sqlite_config.in");
+use teloxide::{
+    dispatching2::dialogue::{
+        serializer::{Bincode, Json},
+        ErasedStorage, RedisStorage, SqliteStorage, Storage,
+    },
+    macros::DialogueState,
+    prelude2::*,
+    types::Me,
+    utils::command::BotCommand,
+};
 
-type MyDialogue = Dialogue<State, MyStorage>;
+type MyDialogue = Dialogue<State, ErasedStorage<State>>;
+type MyStorage = std::sync::Arc<ErasedStorage<State>>;
+type HandlerResult = Result<(), Box<dyn std::error::Error + Send + Sync>>;
 
 #[derive(DialogueState, Clone, serde::Serialize, serde::Deserialize)]
-#[handler_out(anyhow::Result<()>)]
+#[handler_out(HandlerResult)]
 pub enum State {
     #[handler(handle_start)]
     Start,
@@ -34,9 +45,14 @@ pub enum Command {
 async fn main() {
     let bot = Bot::from_env().auto_send();
 
-    let storage = open_storage().await;
+    let storage: MyStorage = if std::env::var("DB_REMEMBER_REDIS").is_ok() {
+        RedisStorage::open("redis://127.0.0.1:6379", Bincode).await.unwrap().erase()
+    } else {
+        SqliteStorage::open("db.sqlite", Json).await.unwrap().erase()
+    };
+
     let handler = Update::filter_message()
-        .enter_dialogue::<Message, MyStorage, State>()
+        .enter_dialogue::<Message, ErasedStorage<State>, State>()
         .dispatch_by::<State>();
 
     Dispatcher::builder(bot, handler)
@@ -47,11 +63,7 @@ async fn main() {
         .await;
 }
 
-async fn handle_start(
-    bot: AutoSend<Bot>,
-    msg: Message,
-    dialogue: MyDialogue,
-) -> anyhow::Result<()> {
+async fn handle_start(bot: AutoSend<Bot>, msg: Message, dialogue: MyDialogue) -> HandlerResult {
     match msg.text().unwrap().parse() {
         Ok(number) => {
             dialogue.update(State::GotNumber(number)).await?;
@@ -75,7 +87,7 @@ async fn handle_got_number(
     dialogue: MyDialogue,
     num: i32,
     me: Me,
-) -> anyhow::Result<()> {
+) -> HandlerResult {
     let ans = msg.text().unwrap();
     let bot_name = me.user.username.unwrap();
 

examples/redis_config.in

@@ -1,7 +0,0 @@
-use teloxide::dispatching2::dialogue::{RedisStorage, serializer::Bincode};
-
-type MyStorage = RedisStorage<Bincode>;
-
-async fn open_storage() -> std::sync::Arc<MyStorage> {
-    RedisStorage::open("redis://127.0.0.1:6379", Bincode).await.unwrap()
-}

examples/sqlite_config.in

@@ -1,7 +0,0 @@
-use teloxide::dispatching2::dialogue::{SqliteStorage, serializer::Json};
-
-type MyStorage = SqliteStorage<Json>;
-
-async fn open_storage() -> std::sync::Arc<MyStorage> {
-    SqliteStorage::open("db.sqlite", Json).await.unwrap()
-}

src/dispatching/dialogue/storage/mod.rs

@@ -74,30 +74,32 @@ pub trait Storage<D> {
     ) -> BoxFuture<'static, Result<Option<D>, Self::Error>>;
 
     /// Erases [`Self::Error`] to [`std::error::Error`].
-    fn erase(self: Arc<Self>) -> ErasedStorage<D>
+    #[must_use]
+    fn erase(self: Arc<Self>) -> Arc<ErasedStorage<D>>
     where
         Self: Sized + Send + Sync + 'static,
-        Self::Error: std::error::Error + 'static,
+        Self::Error: std::error::Error + Send + Sync + 'static,
     {
-        struct Eraser<S>(Arc<S>);
+        Arc::new(Eraser(self))
+    }
+}
 
-        impl<D, S> Storage<D> for Eraser<S>
-        where
+struct Eraser<S>(Arc<S>);
+
+impl<D, S> Storage<D> for Eraser<S>
+where
     S: Storage<D> + Send + Sync + 'static,
-            S::Error: std::error::Error + 'static,
-        {
-            type Error = Box<dyn std::error::Error>;
+    S::Error: std::error::Error + Send + Sync + 'static,
+{
+    type Error = Box<dyn std::error::Error + Send + Sync>;
 
-            fn remove_dialogue(
-                self: Arc<Self>,
-                chat_id: i64,
-            ) -> BoxFuture<'static, Result<(), Self::Error>>
+    fn remove_dialogue(self: Arc<Self>, chat_id: i64) -> BoxFuture<'static, Result<(), Self::Error>>
     where
         D: Send + 'static,
     {
-                Box::pin(async move {
-                    Arc::clone(&self.0).remove_dialogue(chat_id).await.map_err(|e| e.into())
-                })
+        Box::pin(
+            async move { Arc::clone(&self.0).remove_dialogue(chat_id).await.map_err(|e| e.into()) },
+        )
     }
 
     fn update_dialogue(
@@ -109,10 +111,7 @@ pub trait Storage<D> {
         D: Send + 'static,
     {
         Box::pin(async move {
-                    Arc::clone(&self.0)
-                        .update_dialogue(chat_id, dialogue)
-                        .await
-                        .map_err(|e| e.into())
+            Arc::clone(&self.0).update_dialogue(chat_id, dialogue).await.map_err(|e| e.into())
         })
     }
 
@@ -120,18 +119,14 @@ pub trait Storage<D> {
         self: Arc<Self>,
         chat_id: i64,
     ) -> BoxFuture<'static, Result<Option<D>, Self::Error>> {
-                Box::pin(async move {
-                    Arc::clone(&self.0).get_dialogue(chat_id).await.map_err(|e| e.into())
-                })
-            }
-        }
-
-        Arc::new(Eraser(self))
+        Box::pin(
+            async move { Arc::clone(&self.0).get_dialogue(chat_id).await.map_err(|e| e.into()) },
+        )
     }
 }
 
-/// A storage with an erased error type.
-pub type ErasedStorage<D> = Arc<dyn Storage<D, Error = Box<dyn std::error::Error>>>;
+pub type ErasedStorage<D> =
+    dyn Storage<D, Error = Box<dyn std::error::Error + Send + Sync>> + Send + Sync;
 
 #[cfg(test)]
 mod tests {

src/dispatching2/dialogue/mod.rs

@@ -102,7 +102,10 @@ mod get_chat_id;
 
 /// A handle for controlling dialogue state.
 #[derive(Debug)]
-pub struct Dialogue<D, S> {
+pub struct Dialogue<D, S>
+where
+    S: ?Sized,
+{
     storage: Arc<S>,
     chat_id: i64,
     _phantom: PhantomData<D>,
@@ -110,7 +113,10 @@ pub struct Dialogue<D, S> {
 
 // `#[derive]` requires generics to implement `Clone`, but `S` is wrapped around
 // `Arc`, and `D` is wrapped around PhantomData.
-impl<D, S> Clone for Dialogue<D, S> {
+impl<D, S> Clone for Dialogue<D, S>
+where
+    S: ?Sized,
+{
     fn clone(&self) -> Self {
         Dialogue { storage: self.storage.clone(), chat_id: self.chat_id, _phantom: PhantomData }
     }
@@ -119,7 +125,7 @@ impl<D, S> Clone for Dialogue<D, S> {
 impl<D, S> Dialogue<D, S>
 where
     D: Send + 'static,
-    S: Storage<D>,
+    S: Storage<D> + ?Sized,
 {
     /// Constructs a new dialogue with `storage` (where dialogues are stored)
     /// and `chat_id` of a current dialogue.

src/dispatching2/handler_ext.rs

@@ -45,7 +45,7 @@ pub trait HandlerExt<Output> {
     #[must_use]
     fn enter_dialogue<Upd, S, D>(self) -> Self
     where
-        S: Storage<D> + Send + Sync + 'static,
+        S: Storage<D> + ?Sized + Send + Sync + 'static,
         <S as Storage<D>>::Error: Debug + Send,
         D: Default + Send + Sync + 'static,
         Upd: GetChatId + Clone + Send + Sync + 'static;
@@ -72,7 +72,7 @@ where
 
     fn enter_dialogue<Upd, S, D>(self) -> Self
     where
-        S: Storage<D> + Send + Sync + 'static,
+        S: Storage<D> + ?Sized + Send + Sync + 'static,
         <S as Storage<D>>::Error: Debug + Send,
         D: Default + Send + Sync + 'static,
         Upd: GetChatId + Clone + Send + Sync + 'static,