Remove StrongPtr and WeakPtr

We want to encourage users to use Id and WeakId, because they provide much stronger guarantees. The other types can in most cases be emulated as:
type StrongPtr = Option<Id<Object, Shared>>
type WeakPtr = WeakId<Object>

And for the cases where they can't, their implementation is pretty simple anyhow, so advanced users can just use objc2_sys to implement the functionality they need themselves.

Author: madsmtm

objc2/README.md

@@ -29,31 +29,33 @@ unsafe {
 
 The utilities of the `rc` module provide ARC-like semantics for working with
 Objective-C's reference counted objects in Rust.
-A `StrongPtr` retains an object and releases the object when dropped.
-A `WeakPtr` will not retain the object, but can be upgraded to a `StrongPtr`
-and safely fails if the object has been deallocated.
+
+An `Id` retains an object and releases the object when dropped.
+A `WeakId` will not retain the object, but can be upgraded to an `Id` and
+safely fails if the object has been deallocated.
 
 ```rust , no_run
 use objc2::{class, msg_send};
-use objc2::rc::{autoreleasepool, StrongPtr};
+use objc2::rc::{autoreleasepool, Id, Shared, WeakId};
+use objc2::runtime::Object;
 
-// StrongPtr will release the object when dropped
-let obj = unsafe {
-    StrongPtr::new(msg_send![class!(NSObject), new])
+// Id will release the object when dropped
+let obj: Id<Object, Shared> = unsafe {
+    Id::new(msg_send![class!(NSObject), new])
 };
 
 // Cloning retains the object an additional time
 let cloned = obj.clone();
-autoreleasepool(|_| {
-    // Autorelease consumes the StrongPtr, but won't
+autoreleasepool(|pool| {
+    // Autorelease consumes the Id, but won't
     // actually release until the end of an autoreleasepool
-    cloned.autorelease();
+    let obj_ref: &Object = cloned.autorelease(pool);
 });
 
 // Weak references won't retain the object
-let weak = obj.weak();
+let weak = WeakId::new(&obj);
 drop(obj);
-assert!(weak.load().is_null());
+assert!(weak.load().is_none());
 ```
 
 ## Declaring classes

objc2/examples/introspection.rs

@@ -1,4 +1,6 @@
-use objc2::rc::StrongPtr;
+use core::ptr::NonNull;
+
+use objc2::rc::{Id, Owned};
 use objc2::runtime::{Class, Object};
 use objc2::{class, msg_send, sel, Encode};
 
@@ -14,15 +16,15 @@ fn main() {
     }
 
     // Allocate an instance
-    let obj = unsafe {
+    let obj: Id<Object, Owned> = unsafe {
         let obj: *mut Object = msg_send![cls, alloc];
-        let obj: *mut Object = msg_send![obj, init];
-        StrongPtr::new(obj)
+        let obj: NonNull<Object> = msg_send![obj, init];
+        Id::new(obj)
     };
     println!("NSObject address: {:p}", obj);
 
     // Access an ivar of the object
-    let isa: *const Class = unsafe { *(**obj).get_ivar("isa") };
+    let isa: *const Class = unsafe { *obj.get_ivar("isa") };
     println!("NSObject isa: {:?}", isa);
 
     // Inspect a method of the class
@@ -33,6 +35,6 @@ fn main() {
     assert!(*hash_return == usize::ENCODING);
 
     // Invoke a method on the object
-    let hash: usize = unsafe { msg_send![*obj, hash] };
+    let hash: usize = unsafe { msg_send![obj, hash] };
     println!("NSObject hash: {}", hash);
 }

objc2/src/exception.rs

@@ -1,5 +1,8 @@
-use crate::rc::StrongPtr;
+use core::ptr::NonNull;
+
+use crate::rc::Id;
 use crate::runtime::Object;
+use objc2_exception::{r#try, Exception};
 
 // Comment copied from `objc2_exception`
 
@@ -18,6 +21,6 @@ use crate::runtime::Object;
 /// undefined behaviour until `C-unwind` is stabilized, see [RFC-2945].
 ///
 /// [RFC-2945]: https://rust-lang.github.io/rfcs/2945-c-unwind-abi.html
-pub unsafe fn catch_exception<R>(closure: impl FnOnce() -> R) -> Result<R, StrongPtr> {
-    objc2_exception::r#try(closure).map_err(|exception| StrongPtr::new(exception as *mut Object))
+pub unsafe fn catch_exception<R>(closure: impl FnOnce() -> R) -> Result<R, Id<Exception>> {
+    r#try(closure).map_err(|e| Id::new(NonNull::new(e).unwrap()))
 }

objc2/src/rc/id.rs

@@ -517,13 +517,29 @@ mod tests {
     use core::ptr::NonNull;
 
     use super::{Id, Shared};
+    use crate::rc::autoreleasepool;
     use crate::runtime::Object;
     use crate::{class, msg_send};
 
     fn retain_count(obj: &Object) -> usize {
         unsafe { msg_send![obj, retainCount] }
     }
 
+    #[test]
+    fn test_autorelease() {
+        let obj: Id<Object, Shared> = unsafe { Id::new(msg_send![class!(NSObject), new]) };
+
+        let cloned = obj.clone();
+
+        autoreleasepool(|pool| {
+            let _ref = obj.autorelease(pool);
+            assert_eq!(retain_count(&*cloned), 2);
+        });
+
+        // make sure that the autoreleased value has been released
+        assert_eq!(retain_count(&*cloned), 1);
+    }
+
     #[test]
     fn test_clone() {
         let cls = class!(NSObject);

objc2/src/rc/mod.rs

@@ -3,16 +3,8 @@
 //! The utilities of the `rc` module provide ARC-like semantics for working
 //! with Objective-C's reference counted objects in Rust.
 //!
-//! A `StrongPtr` retains an object and releases the object when dropped.
-//! A `WeakPtr` will not retain the object, but can be upgraded to a `StrongPtr`
-//! and safely fails if the object has been deallocated.
-//!
-//! These utilities are not intended to provide a fully safe interface, but can be
-//! useful when writing higher-level Rust wrappers for Objective-C code.
-//!
-//! A smart pointer version of this is provided with the `Id` struct.
-//! To ensure that Objective-C objects are retained and released
-//! at the proper times.
+//! A smart pointer [`Id`] is provided to ensure that Objective-C objects are
+//! retained and released at the proper times.
 //!
 //! To enforce aliasing rules, an `Id` can be either owned or shared; if it is
 //! owned, meaning the `Id` is the only reference to the object, it can be
@@ -33,54 +25,22 @@
 //! [mem-mgmt]: https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/MemoryMgmt/Articles/MemoryMgmt.html
 //! [mem-cf]: https://developer.apple.com/library/archive/documentation/CoreFoundation/Conceptual/CFMemoryMgmt/CFMemoryMgmt.html
 //! [mem-debug]: https://developer.apple.com/library/archive/documentation/Performance/Conceptual/ManagingMemory/Articles/MallocDebug.html
-//!
-//! # Example
-//!
-//! ``` no_run
-//! # use objc2::{class, msg_send};
-//! # use objc2::rc::{autoreleasepool, StrongPtr};
-//! // StrongPtr will release the object when dropped
-//! let obj = unsafe {
-//!     StrongPtr::new(msg_send![class!(NSObject), new])
-//! };
-//!
-//! // Cloning retains the object an additional time
-//! let cloned = obj.clone();
-//! autoreleasepool(|_| {
-//!     // Autorelease consumes the StrongPtr, but won't
-//!     // actually release until the end of an autoreleasepool
-//!     cloned.autorelease();
-//! });
-//!
-//! // Weak references won't retain the object
-//! let weak = obj.weak();
-//! drop(obj);
-//! assert!(weak.load().is_null());
-//! ```
 
 mod autorelease;
 mod id;
 mod ownership;
-mod strong;
-mod weak;
 mod weak_id;
 
 pub use self::autorelease::{autoreleasepool, AutoreleasePool, AutoreleaseSafe};
 pub use self::id::{Id, ShareId};
 pub use self::ownership::{Owned, Ownership, Shared};
-pub use self::strong::StrongPtr;
-pub use self::weak::WeakPtr;
 pub use self::weak_id::WeakId;
 
-// These tests use NSObject, which isn't present for GNUstep
-#[cfg(all(test, target_vendor = "apple"))]
+#[cfg(test)]
 mod tests {
     use core::mem::size_of;
 
-    use super::autoreleasepool;
-    use super::StrongPtr;
     use super::{Id, Owned, Shared, WeakId};
-    use crate::runtime::Object;
 
     pub struct TestType {
         _data: [u8; 0], // TODO: `UnsafeCell`?
@@ -104,65 +64,4 @@ mod tests {
             size_of::<*const ()>()
         );
     }
-
-    #[test]
-    fn test_strong_clone() {
-        fn retain_count(obj: *mut Object) -> usize {
-            unsafe { msg_send![obj, retainCount] }
-        }
-
-        let obj = unsafe { StrongPtr::new(msg_send![class!(NSObject), new]) };
-        assert!(retain_count(*obj) == 1);
-
-        let cloned = obj.clone();
-        assert!(retain_count(*cloned) == 2);
-        assert!(retain_count(*obj) == 2);
-
-        drop(obj);
-        assert!(retain_count(*cloned) == 1);
-    }
-
-    #[test]
-    fn test_weak() {
-        let obj = unsafe { StrongPtr::new(msg_send![class!(NSObject), new]) };
-        let weak = obj.weak();
-
-        let strong = weak.load();
-        assert!(*strong == *obj);
-        drop(strong);
-
-        drop(obj);
-        assert!(weak.load().is_null());
-    }
-
-    #[test]
-    fn test_weak_copy() {
-        let obj = unsafe { StrongPtr::new(msg_send![class!(NSObject), new]) };
-        let weak = obj.weak();
-
-        let weak2 = weak.clone();
-
-        let strong = weak.load();
-        let strong2 = weak2.load();
-        assert!(*strong == *obj);
-        assert!(*strong2 == *obj);
-    }
-
-    #[test]
-    fn test_autorelease() {
-        let obj = unsafe { StrongPtr::new(msg_send![class!(NSObject), new]) };
-
-        fn retain_count(obj: *mut Object) -> usize {
-            unsafe { msg_send![obj, retainCount] }
-        }
-        let cloned = obj.clone();
-
-        autoreleasepool(|_| {
-            obj.autorelease();
-            assert!(retain_count(*cloned) == 2);
-        });
-
-        // make sure that the autoreleased value has been released
-        assert!(retain_count(*cloned) == 1);
-    }
 }