Object protocols without specialization

CHANGELOG.md

@@ -21,6 +21,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Change return type of `PyTuple::as_slice` to `&[&PyAny]`. [#971](https://github.com/PyO3/pyo3/pull/971)
 - Update `num-complex` optional dependendency from `0.2` to `0.3`. [#977](https://github.com/PyO3/pyo3/pull/977)
 - Update `num-bigint` optional dependendency from `0.2` to `0.3`. [#978](https://github.com/PyO3/pyo3/pull/978)
+- `#[pyproto]` is re-implemented without specialization. [#961](https://github.com/PyO3/pyo3/pull/961)
 
 ### Removed
 - Remove `ManagedPyRef` (unused, and needs specialization) [#930](https://github.com/PyO3/pyo3/pull/930)

Cargo.toml

@@ -19,6 +19,7 @@ travis-ci = { repository = "PyO3/pyo3", branch = "master" }
 appveyor = { repository = "fafhrd91/pyo3" }
 
 [dependencies]
+ctor = { version = "0.1", optional = true }
 indoc = { version = "0.3.4", optional = true }
 inventory = { version = "0.1.4", optional = true }
 libc = "0.2.62"
@@ -38,7 +39,7 @@ version_check = "0.9.1"
 
 [features]
 default = ["macros"]
-macros = ["indoc", "inventory", "paste", "pyo3cls", "unindent"]
+macros = ["ctor", "indoc", "inventory", "paste", "pyo3cls", "unindent"]
 
 # this is no longer needed internally, but setuptools-rust assumes this feature
 python3 = []

guide/src/class.md

@@ -956,6 +956,14 @@ impl pyo3::class::methods::HasMethodsInventory for MyClass {
     type Methods = Pyo3MethodsInventoryForMyClass;
 }
 pyo3::inventory::collect!(Pyo3MethodsInventoryForMyClass);
+
+impl pyo3::class::proto_methods::HasProtoRegistry for MyClass {
+    fn registry() -> &'static pyo3::class::proto_methods::PyProtoRegistry {
+        static REGISTRY: pyo3::class::proto_methods::PyProtoRegistry
+            = pyo3::class::proto_methods::PyProtoRegistry::new();
+        &REGISTRY
+    }
+}
 # let gil = Python::acquire_gil();
 # let py = gil.python();
 # let cls = py.get_type::<MyClass>();