Make #[name = ...] attribute in define_class! optional

Part of #713.

Author: madsmtm

crates/objc2/CHANGELOG.md

@@ -6,6 +6,11 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## Unreleased - YYYY-MM-DD
 
+## Added
+* Make `#[name = ...]` in `define_class!` optional. If not specified, the macro
+  will choose a suitable default that makes loading multiple versions of the
+  same library possible.
+
 ## Fixed
 * Fixed undefined behaviour when calling `AnyObject::class` on invalid objects.
 

crates/objc2/examples/hello_world_app.rs

@@ -25,7 +25,6 @@ define_class!(
     // - `Delegate` does not implement `Drop`.
     #[unsafe(super = NSObject)]
     #[thread_kind = MainThreadOnly]
-    #[name = "Delegate"]
     #[ivars = AppDelegateIvars]
     struct Delegate;
 

crates/objc2/src/__macro_helpers/defined_ivars.rs

@@ -499,7 +499,6 @@ mod tests {
 
         define_class!(
             #[unsafe(super(NSObject))]
-            #[name = "ImplsDrop"]
             #[ivars = ()]
             struct ImplsDrop;
 
@@ -533,7 +532,6 @@ mod tests {
 
         define_class!(
             #[unsafe(super(ImplsDrop))]
-            #[name = "IvarsImplDrop"]
             #[ivars = IvarThatImplsDrop]
             struct IvarsImplDrop;
 
@@ -561,7 +559,6 @@ mod tests {
 
         define_class!(
             #[unsafe(super(IvarsImplDrop))]
-            #[name = "BothIvarsAndTypeImplsDrop"]
             #[ivars = IvarThatImplsDrop]
             struct BothIvarsAndTypeImplsDrop;
 
@@ -611,7 +608,6 @@ mod tests {
 
         define_class!(
             #[unsafe(super(NSObject))]
-            #[name = "IvarsNoDrop"]
             #[ivars = Ivar]
             struct IvarsNoDrop;
         );
@@ -631,7 +627,6 @@ mod tests {
 
         define_class!(
             #[unsafe(super(NSObject))]
-            #[name = "IvarZst"]
             #[ivars = Cell<Ivar>]
             struct IvarZst;
 
@@ -694,7 +689,6 @@ mod tests {
     fn test_ivar_access() {
         define_class!(
             #[unsafe(super(NSObject))]
-            #[name = "RcIvar"]
             #[ivars = Cell<Option<Retained<RcTestObject>>>]
             struct RcIvar;
 
@@ -754,7 +748,6 @@ mod tests {
 
         define_class!(
             #[unsafe(super(RcIvar))]
-            #[name = "RcIvarSubclass"]
             #[ivars = RcIvarSubclassIvars]
             struct RcIvarSubclass;
 
@@ -819,7 +812,6 @@ mod tests {
     fn access_invalid() {
         define_class!(
             #[unsafe(super(NSObject))]
-            #[name = "InvalidAccess"]
             // Type has to have a drop flag to detect invalid access
             #[ivars = Retained<NSObject>]
             struct InvalidAccess;
@@ -836,7 +828,6 @@ mod tests {
     fn test_panic_in_drop() {
         define_class!(
             #[unsafe(super(NSObject))]
-            #[name = "DropPanics"]
             struct DropPanics;
         );
 
@@ -865,7 +856,6 @@ mod tests {
 
         define_class!(
             #[unsafe(super(NSObject))]
-            #[name = "IvarDropPanics"]
             #[ivars = DropPanics]
             struct IvarDropPanics;
         );
@@ -886,7 +876,6 @@ mod tests {
         define_class!(
             // SAFETY: Intentionally broken!
             #[unsafe(super(NSObject))]
-            #[name = "DropRetainsAndLeaksSelf"]
             #[derive(Debug)]
             struct DropRetainsAndLeaksSelf;
         );

crates/objc2/src/__macro_helpers/mod.rs

@@ -10,7 +10,7 @@ pub use core::mem::{size_of, ManuallyDrop, MaybeUninit};
 pub use core::ops::Deref;
 pub use core::option::Option::{self, None, Some};
 pub use core::primitive::{bool, isize, str, u8};
-pub use core::{compile_error, concat, panic, stringify};
+pub use core::{compile_error, concat, env, module_path, panic, stringify};
 // TODO: Use `core::cell::LazyCell`
 pub use std::sync::Once;
 

crates/objc2/src/__macro_helpers/msg_send_retained.rs

@@ -365,7 +365,6 @@ mod tests {
 
     define_class!(
         #[unsafe(super(RcTestObject, NSObject))]
-        #[name = "RcTestObjectSubclass"]
         #[derive(Debug, PartialEq, Eq)]
         struct RcTestObjectSubclass;
     );

crates/objc2/src/macros/define_class.rs

@@ -67,12 +67,23 @@
 /// Same [as in `extern_class!`](crate::extern_class#thread_kind---optional).
 ///
 ///
-/// ### `#[name = "..."]` (required)
+/// ### `#[name = "..."]` (optional)
 ///
-/// This is required, and must be unique across the entire application.
+/// Specify the runtime-name for the class. Must be unique across the entire
+/// application. This is useful if the name of a class is used elsewhere, such
+/// as when defining a delegate that needs to be named in e.g. `Info.plist`.
 ///
-/// If you're developing a library, good practice here would be to include
-/// your crate name in the prefix (something like `"MyLibrary_MyClass"`).
+/// If not set, this will default to:
+/// ```ignore
+/// concat!(module_path!(), "::", $class, env!("CARGO_PKG_VERSION"));
+/// ```
+///
+/// E.g. for example `"my_crate::my_module::MyClass0.1.0"`.
+///
+/// If you're developing a library, it is recommended that you do not set
+/// this, and instead rely on the default naming, since that usually works
+/// better with users having multiple SemVer-incompatible versions of your
+/// library in the same binary.
 ///
 ///
 /// ### `#[ivars = ...]` (optional)
@@ -280,10 +291,16 @@
 ///     // - The superclass NSObject does not have any subclassing requirements.
 ///     // - `MyCustomObject` does not implement `Drop`.
 ///     #[unsafe(super(NSObject))]
+///
 ///     // If we were implementing delegate methods like `NSApplicationDelegate`,
 ///     // we would specify the object to only be usable on the main thread:
 ///     // #[thread_kind = MainThreadOnly]
-///     #[name = "MyCustomObject"]
+///
+///     // If we needed to refer to the class from elsewhere, we'd give it a
+///     // name here explicitly.
+///     // #[name = "MyCustomObject"]
+///
+///     // Specify the instance variables this class has.
 ///     #[ivars = Ivars]
 ///     struct MyCustomObject;
 ///
@@ -565,7 +582,15 @@ macro_rules! __define_class_inner {
 
                 const NAME: &'static $crate::__macro_helpers::str = $crate::__fallback_if_not_set! {
                     ($($name)*)
-                    ($crate::__macro_helpers::compile_error!("must set name of class with #[name = ...]"))
+                    (
+                        $crate::__macro_helpers::concat!(
+                            // Module path includes crate name when in library.
+                            $crate::__macro_helpers::module_path!(),
+                            "::",
+                            $crate::__macro_helpers::stringify!($class),
+                            $crate::__macro_helpers::env!("CARGO_PKG_VERSION"),
+                        )
+                    )
                 };
 
                 fn class() -> &'static $crate::runtime::AnyClass {

crates/objc2/src/macros/extern_methods.rs

@@ -114,7 +114,6 @@
 ///     // - The superclass NSObject does not have any subclassing requirements.
 ///     // - `MyObject` does not implement `Drop`.
 ///     #[unsafe(super(NSObject))]
-///     #[name = "MyObject"]
 ///     pub struct MyObject;
 ///
 ///     impl MyObject {
@@ -171,7 +170,6 @@
 /// #
 /// # define_class!(
 /// #     #[unsafe(super(NSObject))]
-/// #     #[name = "MyObject2"]
 /// #     pub struct MyObject;
 /// #
 /// #     impl MyObject {

crates/objc2/src/macros/mod.rs

@@ -1104,7 +1104,6 @@ macro_rules! __class_inner {
 /// #
 /// # objc2::define_class!(
 /// #     #[unsafe(super(NSObject))]
-/// #     #[name = "MyObject"]
 /// #     struct MyObject;
 /// # );
 /// #

crates/objc2/src/rc/retained_traits.rs

@@ -122,7 +122,6 @@ mod tests {
 
     define_class!(
         #[unsafe(super(NSObject))]
-        #[name = "MyCustomCollection"]
         #[derive(PartialEq, Eq, Hash, Debug)]
         struct Collection;
     );

crates/objc2/src/runtime/define.rs

@@ -1081,4 +1081,22 @@ mod tests {
         //
         // let ivar = *obj.get_ivar::<u8>("ivar3");
     }
+
+    #[test]
+    fn auto_name() {
+        define_class!(
+            #[unsafe(super(NSObject))]
+            #[ivars = ()]
+            struct AutoName;
+        );
+
+        let expected = format!(
+            "objc2::runtime::define::tests::AutoName{}",
+            env!("CARGO_PKG_VERSION")
+        );
+
+        let cls = AutoName::class();
+        assert_eq!(cls.name().to_str().unwrap(), expected);
+        assert_eq!(AutoName::NAME, expected);
+    }
 }