Improve documentation

src/async_.rs

@@ -5,18 +5,20 @@ use std::{
     task::{Context, Poll},
 };
 
-use frunk::prelude::HList;
+use crate::{
+    resource::{Resource, ResourceList},
+    slot::SlotDesc,
+    state::Aero,
+};
 
-use crate::{resource::Resource, slot::SlotDesc, state::Aerosol};
+pub(crate) struct WaitForSlot<R: ResourceList, T: Resource> {
-
+    state: Aero<R>,
-pub(crate) struct WaitForSlot<R: HList, T: Resource> {
-    state: Aerosol<R>,
     wait_index: Option<usize>,
     insert_placeholder: bool,
     phantom: PhantomData<fn() -> T>,
 }
 
-impl<R: HList, T: Resource> Future for WaitForSlot<R, T> {
+impl<R: ResourceList, T: Resource> Future for WaitForSlot<R, T> {
     type Output = Option<T>;
 
     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
@@ -26,7 +28,7 @@ impl<R: HList, T: Resource> Future for WaitForSlot<R, T> {
     }
 }
 
-impl<R: HList> Aerosol<R> {
+impl<R: ResourceList> Aero<R> {
     pub(crate) fn wait_for_slot_async<T: Resource>(
         &self,
         insert_placeholder: bool,
@@ -54,13 +56,13 @@ mod tests {
 
     #[tokio::test]
     async fn try_get_some() {
-        let state = Aerosol::new().with(42);
+        let state = Aero::new().with(42);
         assert_eq!(state.try_get_async::<i32>().await, Some(42));
     }
 
     #[tokio::test]
     async fn try_get_none() {
-        let state = Aerosol::new().with("Hello");
+        let state = Aero::new().with("Hello");
         assert_eq!(state.try_get_async::<i32>().await, None);
     }
 }

src/async_constructible.rs

@@ -1,12 +1,12 @@
-use std::{any::Any, sync::Arc};
+use std::{any::Any, marker::PhantomData, sync::Arc};
 
 use async_trait::async_trait;
-use frunk::prelude::HList;
+use frunk::{hlist::Sculptor, HCons, HNil};
 
 use crate::{
-    resource::{unwrap_constructed, Resource},
+    resource::{unwrap_constructed, unwrap_constructed_hlist, Resource, ResourceList},
     slot::SlotDesc,
-    state::Aerosol,
+    state::Aero,
     sync_constructible::Constructible,
 };
 
@@ -17,13 +17,13 @@ pub trait AsyncConstructible: Sized + Any + Send + Sync {
     /// Error type for when resource fails to be constructed.
     type Error: Into<anyhow::Error> + Send + Sync;
     /// Construct the resource with the provided application state.
-    async fn construct_async(aero: &Aerosol) -> Result<Self, Self::Error>;
+    async fn construct_async(aero: &Aero) -> Result<Self, Self::Error>;
     /// Called after construction with the concrete resource to allow the callee
     /// to provide additional resources. Can be used by eg. an `Arc<Foo>` to also
     /// provide an implementation of `Arc<dyn Bar>`.
     async fn after_construction_async(
         _this: &(dyn Any + Send + Sync),
-        _aero: &Aerosol,
+        _aero: &Aero,
     ) -> Result<(), Self::Error> {
         Ok(())
     }
@@ -32,12 +32,12 @@ pub trait AsyncConstructible: Sized + Any + Send + Sync {
 #[async_trait]
 impl<T: Constructible> AsyncConstructible for T {
     type Error = <T as Constructible>::Error;
-    async fn construct_async(aero: &Aerosol) -> Result<Self, Self::Error> {
+    async fn construct_async(aero: &Aero) -> Result<Self, Self::Error> {
         Self::construct(aero)
     }
     async fn after_construction_async(
         this: &(dyn Any + Send + Sync),
-        aero: &Aerosol,
+        aero: &Aero,
     ) -> Result<(), Self::Error> {
         Self::after_construction(this, aero)
     }
@@ -50,13 +50,13 @@ pub trait IndirectlyAsyncConstructible: Sized + Any + Send + Sync {
     /// Error type for when resource fails to be constructed.
     type Error: Into<anyhow::Error> + Send + Sync;
     /// Construct the resource with the provided application state.
-    async fn construct_async(aero: &Aerosol) -> Result<Self, Self::Error>;
+    async fn construct_async(aero: &Aero) -> Result<Self, Self::Error>;
     /// Called after construction with the concrete resource to allow the callee
     /// to provide additional resources. Can be used by eg. an `Arc<Foo>` to also
     /// provide an implementation of `Arc<dyn Bar>`.
     async fn after_construction_async(
         _this: &(dyn Any + Send + Sync),
-        _aero: &Aerosol,
+        _aero: &Aero,
     ) -> Result<(), Self::Error> {
         Ok(())
     }
@@ -66,14 +66,14 @@ pub trait IndirectlyAsyncConstructible: Sized + Any + Send + Sync {
 impl<T: AsyncConstructible> IndirectlyAsyncConstructible for T {
     type Error = T::Error;
 
-    async fn construct_async(aero: &Aerosol) -> Result<Self, Self::Error> {
+    async fn construct_async(aero: &Aero) -> Result<Self, Self::Error> {
         let res = <T as AsyncConstructible>::construct_async(aero).await?;
         <T as AsyncConstructible>::after_construction_async(&res, aero).await?;
         Ok(res)
     }
     async fn after_construction_async(
         this: &(dyn Any + Send + Sync),
-        aero: &Aerosol,
+        aero: &Aero,
     ) -> Result<(), Self::Error> {
         <T as AsyncConstructible>::after_construction_async(this, aero).await
     }
@@ -86,13 +86,13 @@ macro_rules! impl_async_constructible {
             impl<$t: IndirectlyAsyncConstructible> IndirectlyAsyncConstructible for $x {
                 type Error = $t::Error;
 
-                async fn construct_async(aero: &Aerosol) -> Result<Self, Self::Error> {
+                async fn construct_async(aero: &Aero) -> Result<Self, Self::Error> {
                     let res = $y($t::construct_async(aero).await?);
                     <$t as IndirectlyAsyncConstructible>::after_construction_async(&res, aero).await?;
                     Ok(res)
                 }
 
-                async fn after_construction_async(this: &(dyn Any + Send + Sync), aero: &Aerosol) -> Result<(), Self::Error> {
+                async fn after_construction_async(this: &(dyn Any + Send + Sync), aero: &Aero) -> Result<(), Self::Error> {
                     <$t as IndirectlyAsyncConstructible>::after_construction_async(this, aero).await
                 }
             }
@@ -109,10 +109,36 @@ impl_async_constructible! {
 }
 
 /// Implemented for resources which can be asynchronously constructed from other resources. Requires feature `async`.
+/// Do not implement this trait directly, instead implement `AsyncConstructible` and ensure
+/// the remaining type bounds are met for the automatic implementation of `AsyncConstructibleResource`.
 pub trait AsyncConstructibleResource: Resource + IndirectlyAsyncConstructible {}
 impl<T: Resource + IndirectlyAsyncConstructible> AsyncConstructibleResource for T {}
 
-impl<R: HList> Aerosol<R> {
+/// Automatically implemented for resource lists where every resource can be asynchronously constructed.
+#[async_trait]
+pub trait AsyncConstructibleResourceList: ResourceList {
+    /// Construct every resource in this list in the provided aerosol instance
+    async fn construct_async<R: ResourceList>(aero: &Aero<R>) -> anyhow::Result<()>;
+}
+
+#[async_trait]
+impl AsyncConstructibleResourceList for HNil {
+    async fn construct_async<R: ResourceList>(_aero: &Aero<R>) -> anyhow::Result<()> {
+        Ok(())
+    }
+}
+
+#[async_trait]
+impl<H: AsyncConstructibleResource, T: AsyncConstructibleResourceList>
+    AsyncConstructibleResourceList for HCons<H, T>
+{
+    async fn construct_async<R: ResourceList>(aero: &Aero<R>) -> anyhow::Result<()> {
+        aero.try_init_async::<H>().await.map_err(Into::into)?;
+        T::construct_async(aero).await
+    }
+}
+
+impl<R: ResourceList> Aero<R> {
     /// Try to get or construct an instance of `T` asynchronously. Requires feature `async`.
     pub async fn try_obtain_async<T: AsyncConstructibleResource>(&self) -> Result<T, T::Error> {
         match self.try_get_slot() {
@@ -156,12 +182,58 @@ impl<R: HList> Aerosol<R> {
     pub async fn init_async<T: AsyncConstructibleResource>(&self) {
         unwrap_constructed::<T, _>(self.try_init_async::<T>().await)
     }
+
+    /// Builder method equivalent to calling `try_init_async()` but can be chained.
+    pub async fn try_with_constructed_async<T: AsyncConstructibleResource>(
+        self,
+    ) -> Result<Aero<HCons<T, R>>, T::Error> {
+        self.try_init_async::<T>().await?;
+        Ok(Aero {
+            inner: self.inner,
+            phantom: PhantomData,
+        })
+    }
+
+    /// Builder method equivalent to calling `try_init_async()` but can be chained. Panics if construction fails.
+    pub async fn with_constructed_async<T: AsyncConstructibleResource>(self) -> Aero<HCons<T, R>> {
+        unwrap_constructed::<T, _>(self.try_with_constructed_async().await)
+    }
+
+    /// Convert into a different variant of the Aero type. Any missing required resources
+    /// will be automatically asynchronously constructed.
+    pub async fn try_construct_remaining_async<R2: ResourceList, I>(
+        self,
+    ) -> anyhow::Result<Aero<R2>>
+    where
+        R2: Sculptor<R, I>,
+        <R2 as Sculptor<R, I>>::Remainder: AsyncConstructibleResourceList,
+    {
+        <<R2 as Sculptor<R, I>>::Remainder>::construct_async(&self).await?;
+        Ok(Aero {
+            inner: self.inner,
+            phantom: PhantomData,
+        })
+    }
+
+    /// Convert into a different variant of the Aero type. Any missing required resources
+    /// will be automatically asynchronously constructed. Panics if construction of any missing resource fails.
+    pub async fn construct_remaining_async<R2: ResourceList, I>(self) -> Aero<R2>
+    where
+        R2: Sculptor<R, I>,
+        <R2 as Sculptor<R, I>>::Remainder: AsyncConstructibleResourceList,
+    {
+        unwrap_constructed_hlist::<<R2 as Sculptor<R, I>>::Remainder, _>(
+            self.try_construct_remaining_async().await,
+        )
+    }
 }
 
 #[cfg(test)]
 mod tests {
     use std::{convert::Infallible, time::Duration};
 
+    use crate::Aero;
+
     use super::*;
 
     #[derive(Debug, Clone)]
@@ -171,7 +243,7 @@ mod tests {
     impl AsyncConstructible for Dummy {
         type Error = Infallible;
 
-        async fn construct_async(_app_state: &Aerosol) -> Result<Self, Self::Error> {
+        async fn construct_async(_app_state: &Aero) -> Result<Self, Self::Error> {
             tokio::time::sleep(Duration::from_millis(100)).await;
             Ok(Self)
         }
@@ -179,13 +251,13 @@ mod tests {
 
     #[tokio::test]
     async fn obtain() {
-        let state = Aerosol::new();
+        let state = Aero::new();
         state.obtain_async::<Dummy>().await;
     }
 
     #[tokio::test]
     async fn obtain_race() {
-        let state = Aerosol::new();
+        let state = Aero::new();
         let mut handles = Vec::new();
         for _ in 0..100 {
             let state = state.clone();
@@ -205,7 +277,7 @@ mod tests {
     impl AsyncConstructible for DummyRecursive {
         type Error = Infallible;
 
-        async fn construct_async(aero: &Aerosol) -> Result<Self, Self::Error> {
+        async fn construct_async(aero: &Aero) -> Result<Self, Self::Error> {
             aero.obtain_async::<Dummy>().await;
             Ok(Self)
         }
@@ -213,13 +285,13 @@ mod tests {
 
     #[tokio::test]
     async fn obtain_recursive() {
-        let state = Aerosol::new();
+        let state = Aero::new();
         state.obtain_async::<DummyRecursive>().await;
     }
 
     #[tokio::test]
     async fn obtain_recursive_race() {
-        let state = Aerosol::new();
+        let state = Aero::new();
         let mut handles = Vec::new();
         for _ in 0..100 {
             let state = state.clone();
@@ -236,7 +308,7 @@ mod tests {
     impl AsyncConstructible for DummyCyclic {
         type Error = Infallible;
 
-        async fn construct_async(aero: &Aerosol) -> Result<Self, Self::Error> {
+        async fn construct_async(aero: &Aero) -> Result<Self, Self::Error> {
             aero.obtain_async::<DummyCyclic>().await;
             Ok(Self)
         }
@@ -245,7 +317,7 @@ mod tests {
     #[tokio::test]
     #[should_panic(expected = "Cycle detected")]
     async fn obtain_cyclic() {
-        let state = Aerosol::new();
+        let state = Aero::new();
         state.obtain_async::<DummyCyclic>().await;
     }
 
@@ -255,7 +327,7 @@ mod tests {
     impl Constructible for DummySync {
         type Error = Infallible;
 
-        fn construct(_app_state: &Aerosol) -> Result<Self, Self::Error> {
+        fn construct(_app_state: &Aero) -> Result<Self, Self::Error> {
             std::thread::sleep(Duration::from_millis(100));
             Ok(Self)
         }
@@ -268,7 +340,7 @@ mod tests {
     impl AsyncConstructible for DummySyncRecursive {
         type Error = Infallible;
 
-        async fn construct_async(aero: &Aerosol) -> Result<Self, Self::Error> {
+        async fn construct_async(aero: &Aero) -> Result<Self, Self::Error> {
             aero.obtain_async::<DummySync>().await;
             Ok(Self)
         }
@@ -276,13 +348,13 @@ mod tests {
 
     #[tokio::test]
     async fn obtain_sync_recursive() {
-        let state = Aerosol::new();
+        let state = Aero::new();
         state.obtain_async::<DummySyncRecursive>().await;
     }
 
     #[tokio::test]
     async fn obtain_sync_recursive_race() {
-        let state = Aerosol::new();
+        let state = Aero::new();
         let mut handles = Vec::new();
         for _ in 0..100 {
             let state = state.clone();
@@ -299,7 +371,7 @@ mod tests {
     impl AsyncConstructible for DummyNonClone {
         type Error = Infallible;
 
-        async fn construct_async(_app_state: &Aerosol) -> Result<Self, Self::Error> {
+        async fn construct_async(_app_state: &Aero) -> Result<Self, Self::Error> {
             tokio::time::sleep(Duration::from_millis(100)).await;
             Ok(Self)
         }
@@ -307,7 +379,7 @@ mod tests {
 
     #[tokio::test]
     async fn obtain_non_clone() {
-        let state = Aerosol::new();
+        let state = Aero::new();
         state.obtain_async::<Arc<DummyNonClone>>().await;
     }
 
@@ -322,13 +394,13 @@ mod tests {
     impl AsyncConstructible for DummyImpl {
         type Error = Infallible;
 
-        async fn construct_async(_app_state: &Aerosol) -> Result<Self, Self::Error> {
+        async fn construct_async(_app_state: &Aero) -> Result<Self, Self::Error> {
             Ok(Self)
         }
 
         async fn after_construction_async(
             this: &(dyn Any + Send + Sync),
-            aero: &Aerosol,
+            aero: &Aero,
         ) -> Result<(), Self::Error> {
             if let Some(arc) = this.downcast_ref::<Arc<Self>>() {
                 aero.insert(arc.clone() as Arc<dyn DummyTrait>)
@@ -339,8 +411,29 @@ mod tests {
 
     #[tokio::test]
     async fn obtain_impl() {
-        let state = Aerosol::new();
+        let state = Aero::new();
         state.init_async::<Arc<DummyImpl>>().await;
         state.try_get_async::<Arc<dyn DummyTrait>>().await.unwrap();
     }
+
+    #[tokio::test]
+    async fn with_constructed_async() {
+        let state = Aero::new()
+            .with(42)
+            .with_constructed_async::<Dummy>()
+            .await
+            .with("hi");
+        state.get::<Dummy, _>();
+    }
+
+    #[tokio::test]
+    async fn construct_remaining_async() {
+        let state: Aero![i32, Dummy, DummyRecursive, &str] = Aero::new()
+            .with(42)
+            .with("hi")
+            .construct_remaining_async()
+            .await;
+        state.get::<Dummy, _>();
+        state.get::<DummyRecursive, _>();
+    }
 }

src/axum.rs

@@ -4,7 +4,7 @@
 //! resources from within route handlers.
 //!
 //! To make use of these extractors, your application state must either be
-//! an `Aerosol`, or you must implement `FromRef<YourState>` for `Aerosol`.
+//! an `Aero`, or you must implement `FromRef<YourState>` for `Aero`.
 
 use std::any::type_name;
 
@@ -15,7 +15,7 @@ use axum::{
     response::{IntoResponse, Response},
 };
 
-use crate::{Aerosol, AsyncConstructibleResource, ConstructibleResource, Resource};
+use crate::{Aero, AsyncConstructibleResource, ConstructibleResource, Resource};
 
 /// Type of axum Rejection returned when a resource cannot be acquired
 #[derive(Debug, thiserror::Error)]
@@ -59,18 +59,18 @@ impl DependencyError {
     }
 }
 
-/// Get an already-existing resource from the state. Equivalent to calling `Aerosol::try_get_async`.
+/// Get an already-existing resource from the state. Equivalent to calling `Aero::try_get_async`.
 pub struct Dep<T: Resource>(pub T);
 
 #[async_trait]
 impl<T: ConstructibleResource, S: Send + Sync> FromRequestParts<S> for Dep<T>
 where
-    Aerosol: FromRef<S>,
+    Aero: FromRef<S>,
 {
     type Rejection = DependencyError;
 
     async fn from_request_parts(_parts: &mut Parts, state: &S) -> Result<Self, Self::Rejection> {
-        Aerosol::from_ref(state)
+        Aero::from_ref(state)
             .try_get_async()
             .await
             .map(Self)
@@ -78,18 +78,18 @@ where
     }
 }
 
-/// Get a resource from the state, or construct it if it doesn't exist. Equivalent to calling `Aerosol::try_obtain_async`.
+/// Get a resource from the state, or construct it if it doesn't exist. Equivalent to calling `Aero::try_obtain_async`.
 pub struct Obtain<T: AsyncConstructibleResource>(pub T);
 
 #[async_trait]
 impl<T: AsyncConstructibleResource, S: Send + Sync> FromRequestParts<S> for Obtain<T>
 where
-    Aerosol: FromRef<S>,
+    Aero: FromRef<S>,
 {
     type Rejection = DependencyError;
 
     async fn from_request_parts(_parts: &mut Parts, state: &S) -> Result<Self, Self::Rejection> {
-        Aerosol::from_ref(state)
+        Aero::from_ref(state)
             .try_obtain_async()
             .await
             .map(Self)

src/lib.rs

@@ -1,18 +1,127 @@
 #![deny(missing_docs)]
 //! # aerosol
-//! Simple dependency injection for Rust
+//! Simple but powerful dependency injection for Rust.
 //!
-//! Optional features:
+//! This crate provides the `Aero` type, which stores dependencies (called resources) keyed by their
+//! type. Resources can be constructed eagerly at application startup, or on-demand when they are
+//! first needed. Resources can access and/or initialize other resources on creation.
 //!
-//! ## `async`
+//! The crate will detect dependency cycles (if constructing resource A requires resource B which
+//! itself requires resource A) and will panic rather than stack overflow in that case.
+//!
+//! The `Aero` type has an optional type parameter to make certain resources *required*. When
+//! a resource is required it can be accessed infallibly. The `Aero![...]` macro exists to
+//! easily name an `Aero` with a specific set of required resources.
+//!
+//! ## Optional features
+//!
+//! ### `async`
 //!
 //! Allows resources to be constructed asynchrously, and provides a corresponding
 //! `AsyncConstructibleResource` trait.
 //!
-//! ## `axum`
+//! ### `axum`
 //!
 //! Provides integrations with the `axum` web framework. See the `axum` module
 //! for more information.
+//!
+//! ## Example usage
+//!
+//! ```rust
+//! use std::{sync::Arc, any::Any};
+//!
+//! # struct PostmarkClient;
+//! # #[derive(Clone)]
+//! # struct ConnectionPool;
+//! # #[derive(Clone)]
+//! # struct MessageQueue;
+//! # #[derive(Clone)]
+//! # struct MagicNumber(i32);
+//! # trait EmailSender: Send + Sync { fn send(&self) {} }
+//! # impl EmailSender for PostmarkClient {}
+//! # impl PostmarkClient { fn new() -> anyhow::Result<Self> { Ok(Self) }}
+//! use aerosol::{Aero, Constructible};
+//!
+//! // Here, we can list all the things we want to guarantee are in
+//! // our app state. This is entirely optional, we could also just
+//! // use the `Aero` type with default arguments and check that
+//! // resources are present at runtime.
+//! type AppState = Aero![
+//!     Arc<PostmarkClient>,
+//!     Arc<dyn EmailSender>,
+//!     ConnectionPool,
+//!     MessageQueue,
+//!     MagicNumber,
+//! ];
+//!
+//! fn main() {
+//!     let app_state: AppState = Aero::new()
+//!         // Directly add a resource which doesn't implement `Constructible`.
+//!         .with(MagicNumber(42))
+//!         // Construct an `Arc<PostmarkClient>` resource in the AppState
+//!         .with_constructed::<Arc<PostmarkClient>>()
+//!         // Check that an implementation of `EmailSender` was added as a result
+//!         .assert::<Arc<dyn EmailSender>>()
+//!         // Automatically construct anything else necessary for our AppState
+//!         // (in this case, `ConnectionPool` and `MessageQueue`)
+//!         .construct_remaining();
+//!
+//!     // Add an extra resource
+//!     app_state.insert("Hello, world");
+//!
+//!     run(app_state);
+//! }
+//!
+//! fn run(app_state: AppState) {
+//!     // The `get()` method is infallible because the `Arc<dyn EmailSender>` was
+//!     // explicitly listed when defining our `AppState`.
+//!     let email_sender: Arc<dyn EmailSender> = app_state.get();
+//!     email_sender.send(/* email */);
+//!
+//!     // We have to use `try_get()` here because a `&str` is not guaranteed to
+//!     // exist on our `AppState`.
+//!     let hello_message: &str = app_state.try_get().unwrap();
+//!     println!("{hello_message}");
+//!
+//!     // ... more application logic
+//! }
+//!
+//! // The `Constructible` trait can be implemented to allow resources to be automatically
+//! // constructed.
+//! impl Constructible for PostmarkClient {
+//!     type Error = anyhow::Error;
+//!
+//!     fn construct(aero: &Aero) -> Result<Self, Self::Error> {
+//!         PostmarkClient::new(/* initialize using environment variables */)
+//!     }
+//!
+//!     fn after_construction(this: &(dyn Any + Send + Sync), aero: &Aero) -> Result<(), Self::Error> {
+//!         // We can use this to automatically populate extra resources on the context.
+//!         // For example, in this case we can make it so that if an `Arc<PostmarkClient>` gets
+//!         // constructed, we also provide `Arc<dyn EmailSender>`.
+//!         if let Some(arc) = this.downcast_ref::<Arc<Self>>() {
+//!             aero.insert(arc.clone() as Arc<dyn EmailSender>)
+//!         }
+//!         Ok(())
+//!     }
+//! }
+//!
+//! impl Constructible for ConnectionPool {
+//!     type Error = anyhow::Error;
+//!     fn construct(aero: &Aero) -> Result<Self, Self::Error> {
+//!         // ...
+//! #       Ok(ConnectionPool)
+//!     }
+//! }
+//!
+//! impl Constructible for MessageQueue {
+//!     type Error = anyhow::Error;
+//!     fn construct(aero: &Aero) -> Result<Self, Self::Error> {
+//!         // ...
+//! #       Ok(MessageQueue)
+//!     }
+//! }
+//! ```
 pub use frunk;
 
 #[cfg(feature = "async")]
@@ -28,12 +137,15 @@ mod state;
 mod sync;
 mod sync_constructible;
 
-pub use resource::Resource;
+pub use resource::{Resource, ResourceList};
-pub use state::Aerosol;
+pub use state::Aero;
 
-pub use sync_constructible::{Constructible, ConstructibleResource, IndirectlyConstructible};
+pub use sync_constructible::{
+    Constructible, ConstructibleResource, ConstructibleResourceList, IndirectlyConstructible,
+};
 
 #[cfg(feature = "async")]
 pub use async_constructible::{
-    AsyncConstructible, AsyncConstructibleResource, IndirectlyAsyncConstructible,
+    AsyncConstructible, AsyncConstructibleResource, AsyncConstructibleResourceList,
+    IndirectlyAsyncConstructible,
 };

src/macros.rs

@@ -1,7 +1,14 @@
-/// Define a custom `Aerosol` alias with a specific set of required types
+/// Define a custom `Aero` alias with a specific set of required types
+///
+/// Example usage:
+/// ```rust
+/// use aerosol::Aero;
+///
+/// type AppState = Aero![&'static str, i32, bool];
+/// ```
 #[macro_export]
 macro_rules! Aero {
     ($($tok:tt)*) => {
-        $crate::Aerosol<$crate::frunk::HList![$($tok)*]>
+        $crate::Aero<$crate::frunk::HList![$($tok)*]>
     };
 }

src/resource.rs

@@ -1,14 +1,38 @@
 use std::any::{type_name, Any};
 
+use frunk::{prelude::HList, HCons, HNil};
+
+use crate::Aero;
+
 /// Bound on the types that can be used as an aerosol resource.
 pub trait Resource: Any + Send + Sync + Clone {}
 impl<T: Any + Send + Sync + Clone> Resource for T {}
 
+/// A compile-time list of resource types which are statically guaranteed to be present.
+pub trait ResourceList: HList + Any + Send + Sync + Clone {
+    /// Test at runtmie whether every resource in this list is present in the given Aero instance.
+    fn test<R: ResourceList>(aero: &Aero<R>) -> bool;
+}
+impl ResourceList for HNil {
+    fn test<R: ResourceList>(_aero: &Aero<R>) -> bool {
+        true
+    }
+}
+impl<H: Resource, T: ResourceList> ResourceList for HCons<H, T> {
+    fn test<R: ResourceList>(aero: &Aero<R>) -> bool {
+        aero.has::<H>() && T::test(aero)
+    }
+}
+
+pub(crate) fn missing_resource<T: Resource>() -> ! {
+    panic!("Resource `{}` does not exist", type_name::<T>())
+}
+
 pub(crate) fn unwrap_resource<T: Resource>(opt: Option<T>) -> T {
     if let Some(value) = opt {
         value
     } else {
-        panic!("Resource `{}` does not exist", type_name::<T>())
+        missing_resource::<T>()
     }
 }
 
@@ -19,6 +43,17 @@ pub(crate) fn unwrap_constructed<T: Resource, U>(res: Result<U, impl Into<anyhow
     }
 }
 
+pub(crate) fn unwrap_constructed_hlist<T, U>(res: Result<U, impl Into<anyhow::Error>>) -> U {
+    match res {
+        Ok(x) => x,
+        Err(e) => panic!(
+            "Failed to construct one of `{}`: {}",
+            type_name::<T>(),
+            e.into()
+        ),
+    }
+}
+
 pub(crate) fn duplicate_resource<T: Resource>() -> ! {
     panic!(
         "Duplicate resource: attempted to add a second `{}`",

src/state.rs

@@ -3,18 +3,17 @@ use std::{any::Any, marker::PhantomData, sync::Arc, task::Poll};
 use anymap::hashbrown::{Entry, Map};
 use frunk::{
     hlist::{HFoldRightable, Sculptor},
-    prelude::HList,
     HCons, HNil, Poly,
 };
 use parking_lot::RwLock;
 
 use crate::{
-    resource::{cyclic_resource, duplicate_resource, Resource},
+    resource::{cyclic_resource, duplicate_resource, missing_resource, Resource, ResourceList},
     slot::{Slot, SlotDesc, ThreadOrWaker},
 };
 
 #[derive(Debug, Default)]
-struct InnerAerosol {
+pub(crate) struct InnerAero {
     items: Map<dyn Any + Send + Sync>,
 }
 
@@ -23,12 +22,12 @@ struct InnerAerosol {
 /// Can be cheaply cloned.
 #[derive(Debug)]
 #[repr(transparent)]
-pub struct Aerosol<R: HList = HNil> {
+pub struct Aero<R: ResourceList = HNil> {
-    inner: Arc<RwLock<InnerAerosol>>,
+    pub(crate) inner: Arc<RwLock<InnerAero>>,
-    phantom: PhantomData<Arc<R>>,
+    pub(crate) phantom: PhantomData<Arc<R>>,
 }
 
-impl Aerosol {
+impl Aero {
     /// Construct a new instance of the type with no initial resources.
     pub fn new() -> Self {
         Self {
@@ -38,7 +37,7 @@ impl Aerosol {
     }
 }
 
-impl<R: HList> Clone for Aerosol<R> {
+impl<R: ResourceList> Clone for Aero<R> {
     fn clone(&self) -> Self {
         Self {
             inner: self.inner.clone(),
@@ -47,41 +46,24 @@ impl<R: HList> Clone for Aerosol<R> {
     }
 }
 
-struct AerosolBuilderFolder;
+struct AerosolDefaultFolder;
-impl<R: HList, T: Resource> frunk::Func<(Aerosol<R>, T)> for AerosolBuilderFolder {
+impl<R: ResourceList, T: Resource> frunk::Func<(Aero<R>, T)> for AerosolDefaultFolder {
-    type Output = Aerosol<HCons<T, R>>;
+    type Output = Aero<HCons<T, R>>;
-    fn call((aero, value): (Aerosol<R>, T)) -> Self::Output {
+    fn call((aero, value): (Aero<R>, T)) -> Self::Output {
         aero.with(value)
     }
 }
 
-#[doc(hidden)]
-pub trait HTestable {
-    fn test<R: HList>(aero: &Aerosol<R>) -> bool;
-}
-
-impl HTestable for HNil {
-    fn test<R: HList>(_aero: &Aerosol<R>) -> bool {
-        true
-    }
-}
-
-impl<H: Resource, T: HTestable> HTestable for HCons<H, T> {
-    fn test<R: HList>(aero: &Aerosol<R>) -> bool {
-        aero.has::<H>() && T::test(aero)
-    }
-}
-
 impl<
-        R: Default + HFoldRightable<Poly<AerosolBuilderFolder>, Aerosol, Output = Aerosol<R>> + HList,
+        R: Default + HFoldRightable<Poly<AerosolDefaultFolder>, Aero, Output = Aero<R>> + ResourceList,
-    > Default for Aerosol<R>
+    > Default for Aero<R>
 {
     fn default() -> Self {
-        R::default().foldr(Poly(AerosolBuilderFolder), Aerosol::new())
+        R::default().foldr(Poly(AerosolDefaultFolder), Aero::new())
     }
 }
 
-impl<R: HList> Aerosol<R> {
+impl<R: ResourceList> Aero<R> {
     /// Directly insert a resource into the collection. Panics if a resource of the
     /// same type already exists.
     pub fn insert<T: Resource>(&self, value: T) {
@@ -94,44 +76,44 @@ impl<R: HList> Aerosol<R> {
     }
 
     /// Builder method equivalent to calling `insert()` but can be chained.
-    pub fn with<T: Resource>(self, value: T) -> Aerosol<HCons<T, R>> {
+    pub fn with<T: Resource>(self, value: T) -> Aero<HCons<T, R>> {
         self.insert(value);
-        Aerosol {
+        Aero {
             inner: self.inner,
             phantom: PhantomData,
         }
     }
 
-    /// Convert into a different variant of the Aerosol type. The new variant must
+    /// Convert into a different variant of the Aero type. The new variant must
     /// not require any resources which are not required as part of this type.
-    pub fn into<R2: HList, I>(self) -> Aerosol<R2>
+    pub fn into<R2: ResourceList, I>(self) -> Aero<R2>
     where
         R: Sculptor<R2, I>,
     {
-        Aerosol {
+        Aero {
             inner: self.inner,
             phantom: PhantomData,
         }
     }
 
-    /// Reborrow as a different variant of the Aerosol type. The new variant must
+    /// Reborrow as a different variant of the Aero type. The new variant must
     /// not require any resources which are not required as part of this type.
     #[allow(clippy::should_implement_trait)]
-    pub fn as_ref<R2: HList, I>(&self) -> &Aerosol<R2>
+    pub fn as_ref<R2: ResourceList, I>(&self) -> &Aero<R2>
     where
         R: Sculptor<R2, I>,
     {
-        // Safety: all Aerosol variants are `#[repr(transparent)]` wrappers around
+        // Safety: all Aero variants are `#[repr(transparent)]` wrappers around
         // the same concrete type.
         unsafe { std::mem::transmute(self) }
     }
 
-    /// Try to convert into a different variant of the Aerosol type. Returns the
+    /// Try to convert into a different variant of the Aero type. Returns the
     /// original type if one or more of the required resources are not fully
     /// constructed.
-    pub fn try_into<R2: HList + HTestable>(self) -> Result<Aerosol<R2>, Self> {
+    pub fn try_into<R2: ResourceList>(self) -> Result<Aero<R2>, Self> {
         if R2::test(&self) {
-            Ok(Aerosol {
+            Ok(Aero {
                 inner: self.inner,
                 phantom: PhantomData,
             })
@@ -140,13 +122,13 @@ impl<R: HList> Aerosol<R> {
         }
     }
 
-    /// Try to convert into a different variant of the Aerosol type. Returns
+    /// Try to convert into a different variant of the Aero type. Returns
     /// `None` if one or more of the required resources are not fully
     /// constructed.
-    pub fn try_as_ref<R2: HList + HTestable>(&self) -> Option<&Aerosol<R2>> {
+    pub fn try_as_ref<R2: ResourceList>(&self) -> Option<&Aero<R2>> {
         if R2::test(self) {
             Some(
-                // Safety: all Aerosol variants are `#[repr(transparent)]` wrappers around
+                // Safety: all Aero variants are `#[repr(transparent)]` wrappers around
                 // the same concrete type.
                 unsafe { std::mem::transmute(self) },
             )
@@ -164,6 +146,24 @@ impl<R: HList> Aerosol<R> {
         )
     }
 
+    /// Assert that a resource exists, returns `self` unchanged if not
+    pub fn try_assert<T: Resource>(self) -> Result<Aero<HCons<T, R>>, Self> {
+        if self.has::<T>() {
+            Ok(Aero {
+                inner: self.inner,
+                phantom: PhantomData,
+            })
+        } else {
+            Err(self)
+        }
+    }
+
+    /// Assert that a resource exists, panic if not
+    pub fn assert<T: Resource>(self) -> Aero<HCons<T, R>> {
+        self.try_assert()
+            .unwrap_or_else(|_| missing_resource::<T>())
+    }
+
     pub(crate) fn try_get_slot<T: Resource>(&self) -> Option<SlotDesc<T>> {
         self.inner.read().items.get().map(Slot::desc)
     }
@@ -211,14 +211,14 @@ impl<R: HList> Aerosol<R> {
     }
 }
 
-impl<R: HList> AsRef<Aerosol> for Aerosol<R> {
+impl<R: ResourceList> AsRef<Aero> for Aero<R> {
-    fn as_ref(&self) -> &Aerosol {
+    fn as_ref(&self) -> &Aero {
-        Aerosol::as_ref(self)
+        Aero::as_ref(self)
     }
 }
 
-impl<H, T: HList> From<Aerosol<HCons<H, T>>> for Aerosol {
+impl<H: Resource, T: ResourceList> From<Aero<HCons<H, T>>> for Aero {
-    fn from(value: Aerosol<HCons<H, T>>) -> Self {
+    fn from(value: Aero<HCons<H, T>>) -> Self {
         value.into()
     }
 }
@@ -227,32 +227,37 @@ impl<H, T: HList> From<Aerosol<HCons<H, T>>> for Aerosol {
 mod tests {
     use crate::Aero;
 
-    use super::*;
-
     #[test]
     fn create() {
-        let state = Aerosol::new().with(42);
+        let state = Aero::new().with(42);
         state.insert("Hello, world!");
     }
 
     #[test]
     #[should_panic]
     fn duplicate() {
-        let state = Aerosol::new().with(13);
+        let state = Aero::new().with(13);
         state.insert(42);
     }
 
     #[test]
     fn default() {
-        let state: Aero![i32] = Aerosol::default();
+        let state: Aero![i32] = Aero::default();
         state.insert("Hello, world!");
     }
 
     #[test]
     fn convert() {
-        let state: Aero![i32, String, f32] = Aerosol::default();
+        let state: Aero![i32, String, f32] = Aero::default();
         state.insert("Hello, world!");
         let state2: Aero![f32, String] = state.into();
         let _state3: Aero![i32, String, f32] = state2.try_into().unwrap();
     }
+
+    #[test]
+    fn assert() {
+        let state: Aero![i32, String, f32] = Aero::default();
+        state.insert("Hello, world!");
+        let _state2: Aero![&str, f32] = state.assert::<&str>().into();
+    }
 }

src/sync.rs

@@ -1,11 +1,11 @@
 use std::{task::Poll, thread};
 
-use frunk::{hlist::Plucker, prelude::HList};
+use frunk::hlist::Plucker;
 
 use crate::{
-    resource::{unwrap_resource, Resource},
+    resource::{unwrap_resource, Resource, ResourceList},
     slot::SlotDesc,
-    state::Aerosol,
+    state::Aero,
 };
 
 #[cfg(target_family = "wasm")]
@@ -18,7 +18,7 @@ pub fn safe_park() {
     std::thread::park();
 }
 
-impl<R: HList> Aerosol<R> {
+impl<R: ResourceList> Aero<R> {
     /// Synchronously wait for the slot for `T` to not have a placeholder.
     /// Returns immediately if there is no `T` present, or if `T`'s slot is filled.
     pub(crate) fn wait_for_slot<T: Resource>(&self, insert_placeholder: bool) -> Option<T> {
@@ -54,19 +54,19 @@ mod tests {
 
     #[test]
     fn get_with() {
-        let state = Aerosol::new().with(42);
+        let state = Aero::new().with(42);
         assert_eq!(state.get::<i32, _>(), 42);
     }
 
     #[test]
     fn try_get_some() {
-        let state = Aerosol::new().with(42);
+        let state = Aero::new().with(42);
         assert_eq!(state.try_get::<i32>(), Some(42));
     }
 
     #[test]
     fn try_get_none() {
-        let state = Aerosol::new().with("Hello");
+        let state = Aero::new().with("Hello");
         assert_eq!(state.try_get::<i32>(), None);
     }
 }

src/sync_constructible.rs

@@ -1,11 +1,11 @@
-use std::{any::Any, sync::Arc};
+use std::{any::Any, marker::PhantomData, sync::Arc};
 
-use frunk::prelude::HList;
+use frunk::{hlist::Sculptor, HCons, HNil};
 
 use crate::{
-    resource::{unwrap_constructed, Resource},
+    resource::{unwrap_constructed, unwrap_constructed_hlist, Resource, ResourceList},
     slot::SlotDesc,
-    state::Aerosol,
+    state::Aero,
 };
 
 /// Implemented for values which can be constructed from other resources.
@@ -13,14 +13,14 @@ pub trait Constructible: Sized + Any + Send + Sync {
     /// Error type for when resource fails to be constructed.
     type Error: Into<anyhow::Error> + Send + Sync;
     /// Construct the resource with the provided application state.
-    fn construct(aero: &Aerosol) -> Result<Self, Self::Error>;
+    fn construct(aero: &Aero) -> Result<Self, Self::Error>;
 
     /// Called after construction with the concrete resource to allow the callee
     /// to provide additional resources. Can be used by eg. an `Arc<Foo>` to also
     /// provide an implementation of `Arc<dyn Bar>`.
     fn after_construction(
         _this: &(dyn Any + Send + Sync),
-        _aero: &Aerosol,
+        _aero: &Aero,
     ) -> Result<(), Self::Error> {
         Ok(())
     }
@@ -31,13 +31,13 @@ pub trait IndirectlyConstructible: Sized + Any + Send + Sync {
     /// Error type for when resource fails to be constructed.
     type Error: Into<anyhow::Error> + Send + Sync;
     /// Construct the resource with the provided application state.
-    fn construct(aero: &Aerosol) -> Result<Self, Self::Error>;
+    fn construct(aero: &Aero) -> Result<Self, Self::Error>;
     /// Called after construction with the concrete resource to allow the callee
     /// to provide additional resources. Can be used by eg. an `Arc<Foo>` to also
     /// provide an implementation of `Arc<dyn Bar>`.
     fn after_construction(
         _this: &(dyn Any + Send + Sync),
-        _aero: &Aerosol,
+        _aero: &Aero,
     ) -> Result<(), Self::Error> {
         Ok(())
     }
@@ -46,16 +46,13 @@ pub trait IndirectlyConstructible: Sized + Any + Send + Sync {
 impl<T: Constructible> IndirectlyConstructible for T {
     type Error = T::Error;
 
-    fn construct(aero: &Aerosol) -> Result<Self, Self::Error> {
+    fn construct(aero: &Aero) -> Result<Self, Self::Error> {
         let res = <T as Constructible>::construct(aero)?;
         <T as Constructible>::after_construction(&res, aero)?;
         Ok(res)
     }
 
-    fn after_construction(
+    fn after_construction(this: &(dyn Any + Send + Sync), aero: &Aero) -> Result<(), Self::Error> {
-        this: &(dyn Any + Send + Sync),
-        aero: &Aerosol,
-    ) -> Result<(), Self::Error> {
         <T as Constructible>::after_construction(this, aero)
     }
 }
@@ -66,13 +63,13 @@ macro_rules! impl_constructible {
             impl<$t: IndirectlyConstructible> IndirectlyConstructible for $x {
                 type Error = $t::Error;
 
-                fn construct(aero: &Aerosol) -> Result<Self, Self::Error> {
+                fn construct(aero: &Aero) -> Result<Self, Self::Error> {
                     let res = $y($t::construct(aero)?);
                     <$t as IndirectlyConstructible>::after_construction(&res, aero)?;
                     Ok(res)
                 }
 
-                fn after_construction(this: &(dyn Any + Send + Sync), aero: &Aerosol) -> Result<(), Self::Error> {
+                fn after_construction(this: &(dyn Any + Send + Sync), aero: &Aero) -> Result<(), Self::Error> {
                     <$t as IndirectlyConstructible>::after_construction(this, aero)
                 }
             }
@@ -89,10 +86,33 @@ impl_constructible! {
 }
 
 /// Implemented for resources which can be constructed from other resources.
+/// Do not implement this trait directly, instead implement `Constructible` and ensure
+/// the remaining type bounds are met for the automatic implementation of `ConstructibleResource`.
 pub trait ConstructibleResource: Resource + IndirectlyConstructible {}
 impl<T: Resource + IndirectlyConstructible> ConstructibleResource for T {}
 
-impl<R: HList> Aerosol<R> {
+/// Automatically implemented for resource lists where every resource can be constructed.
+pub trait ConstructibleResourceList: ResourceList {
+    /// Construct every resource in this list in the provided aerosol instance
+    fn construct<R: ResourceList>(aero: &Aero<R>) -> anyhow::Result<()>;
+}
+
+impl ConstructibleResourceList for HNil {
+    fn construct<R: ResourceList>(_aero: &Aero<R>) -> anyhow::Result<()> {
+        Ok(())
+    }
+}
+
+impl<H: ConstructibleResource, T: ConstructibleResourceList> ConstructibleResourceList
+    for HCons<H, T>
+{
+    fn construct<R: ResourceList>(aero: &Aero<R>) -> anyhow::Result<()> {
+        aero.try_init::<H>().map_err(Into::into)?;
+        T::construct(aero)
+    }
+}
+
+impl<R: ResourceList> Aero<R> {
     /// Try to get or construct an instance of `T`.
     pub fn try_obtain<T: ConstructibleResource>(&self) -> Result<T, T::Error> {
         match self.try_get_slot() {
@@ -136,12 +156,56 @@ impl<R: HList> Aerosol<R> {
     pub fn init<T: ConstructibleResource>(&self) {
         unwrap_constructed::<T, _>(self.try_init::<T>())
     }
+
+    /// Builder method equivalent to calling `try_init()` but can be chained.
+    pub fn try_with_constructed<T: ConstructibleResource>(
+        self,
+    ) -> Result<Aero<HCons<T, R>>, T::Error> {
+        self.try_init::<T>()?;
+        Ok(Aero {
+            inner: self.inner,
+            phantom: PhantomData,
+        })
+    }
+
+    /// Builder method equivalent to calling `try_init()` but can be chained. Panics if construction fails.
+    pub fn with_constructed<T: ConstructibleResource>(self) -> Aero<HCons<T, R>> {
+        unwrap_constructed::<T, _>(self.try_with_constructed())
+    }
+
+    /// Convert into a different variant of the Aero type. Any missing required resources
+    /// will be automatically constructed.
+    pub fn try_construct_remaining<R2: ResourceList, I>(self) -> anyhow::Result<Aero<R2>>
+    where
+        R2: Sculptor<R, I>,
+        <R2 as Sculptor<R, I>>::Remainder: ConstructibleResourceList,
+    {
+        <<R2 as Sculptor<R, I>>::Remainder>::construct(&self)?;
+        Ok(Aero {
+            inner: self.inner,
+            phantom: PhantomData,
+        })
+    }
+
+    /// Convert into a different variant of the Aero type. Any missing required resources
+    /// will be automatically constructed. Panics if construction of any missing resource fails.
+    pub fn construct_remaining<R2: ResourceList, I>(self) -> Aero<R2>
+    where
+        R2: Sculptor<R, I>,
+        <R2 as Sculptor<R, I>>::Remainder: ConstructibleResourceList,
+    {
+        unwrap_constructed_hlist::<<R2 as Sculptor<R, I>>::Remainder, _>(
+            self.try_construct_remaining(),
+        )
+    }
 }
 
 #[cfg(test)]
 mod tests {
     use std::{convert::Infallible, thread::scope, time::Duration};
 
+    use crate::Aero;
+
     use super::*;
 
     #[derive(Debug, Clone)]
@@ -150,7 +214,7 @@ mod tests {
     impl Constructible for Dummy {
         type Error = Infallible;
 
-        fn construct(_app_state: &Aerosol) -> Result<Self, Self::Error> {
+        fn construct(_app_state: &Aero) -> Result<Self, Self::Error> {
             std::thread::sleep(Duration::from_millis(100));
             Ok(Self)
         }
@@ -158,13 +222,13 @@ mod tests {
 
     #[test]
     fn obtain() {
-        let state = Aerosol::new();
+        let state = Aero::new();
         state.obtain::<Dummy>();
     }
 
     #[test]
     fn obtain_race() {
-        let state = Aerosol::new();
+        let state = Aero::new();
         scope(|s| {
             for _ in 0..100 {
                 s.spawn(|| state.obtain::<Dummy>());
@@ -178,7 +242,7 @@ mod tests {
     impl Constructible for DummyRecursive {
         type Error = Infallible;
 
-        fn construct(aero: &Aerosol) -> Result<Self, Self::Error> {
+        fn construct(aero: &Aero) -> Result<Self, Self::Error> {
             aero.obtain::<Dummy>();
             Ok(Self)
         }
@@ -186,13 +250,13 @@ mod tests {
 
     #[test]
     fn obtain_recursive() {
-        let state = Aerosol::new();
+        let state = Aero::new();
         state.obtain::<DummyRecursive>();
     }
 
     #[test]
     fn obtain_recursive_race() {
-        let state = Aerosol::new();
+        let state = Aero::new();
         scope(|s| {
             for _ in 0..100 {
                 s.spawn(|| state.obtain::<DummyRecursive>());
@@ -206,7 +270,7 @@ mod tests {
     impl Constructible for DummyCyclic {
         type Error = Infallible;
 
-        fn construct(aero: &Aerosol) -> Result<Self, Self::Error> {
+        fn construct(aero: &Aero) -> Result<Self, Self::Error> {
             aero.obtain::<DummyCyclic>();
             Ok(Self)
         }
@@ -215,7 +279,7 @@ mod tests {
     #[test]
     #[should_panic(expected = "Cycle detected")]
     fn obtain_cyclic() {
-        let state = Aerosol::new();
+        let state = Aero::new();
         state.obtain::<DummyCyclic>();
     }
 
@@ -225,7 +289,7 @@ mod tests {
     impl Constructible for DummyNonClone {
         type Error = Infallible;
 
-        fn construct(_app_state: &Aerosol) -> Result<Self, Self::Error> {
+        fn construct(_app_state: &Aero) -> Result<Self, Self::Error> {
             std::thread::sleep(Duration::from_millis(100));
             Ok(Self)
         }
@@ -233,7 +297,7 @@ mod tests {
 
     #[test]
     fn obtain_non_clone() {
-        let state = Aerosol::new();
+        let state = Aero::new();
         state.obtain::<Arc<DummyNonClone>>();
     }
 
@@ -247,13 +311,13 @@ mod tests {
     impl Constructible for DummyImpl {
         type Error = Infallible;
 
-        fn construct(_app_state: &Aerosol) -> Result<Self, Self::Error> {
+        fn construct(_app_state: &Aero) -> Result<Self, Self::Error> {
             Ok(Self)
         }
 
         fn after_construction(
             this: &(dyn Any + Send + Sync),
-            aero: &Aerosol,
+            aero: &Aero,
         ) -> Result<(), Self::Error> {
             if let Some(arc) = this.downcast_ref::<Arc<Self>>() {
                 aero.insert(arc.clone() as Arc<dyn DummyTrait>)
@@ -264,8 +328,22 @@ mod tests {
 
     #[test]
     fn obtain_impl() {
-        let state = Aerosol::new();
+        let state = Aero::new();
         state.init::<Arc<DummyImpl>>();
         state.try_get::<Arc<dyn DummyTrait>>().unwrap();
     }
+
+    #[test]
+    fn with_constructed() {
+        let state = Aero::new().with(42).with_constructed::<Dummy>().with("hi");
+        state.get::<Dummy, _>();
+    }
+
+    #[test]
+    fn construct_remaining() {
+        let state: Aero![i32, Dummy, DummyRecursive, &str] =
+            Aero::new().with(42).with("hi").construct_remaining();
+        state.get::<Dummy, _>();
+        state.get::<DummyRecursive, _>();
+    }
 }