Remove ObjectProtocol::get_base and fix class.md

CHANGELOG.md

@@ -44,7 +44,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 * `AsPyRef::as_mut/with/with_mut/into_py/into_mut_py`. [#770](https://github.com/PyO3/pyo3/pull/770)
 * `PyTryFrom::try_from_mut/try_from_mut_exact/try_from_mut_unchecked`. [#770](https://github.com/PyO3/pyo3/pull/770)
 * `Python::mut_from_owned_ptr/mut_from_borrowed_ptr`. [#770](https://github.com/PyO3/pyo3/pull/770)
-* `ObjectProtocol::get_mut_base`. [#770](https://github.com/PyO3/pyo3/pull/770)
+* `ObjectProtocol::get_base/get_mut_base`. [#770](https://github.com/PyO3/pyo3/pull/770)
 
 ## [0.8.5]
 

guide/src/class.md

@@ -114,7 +114,7 @@ from Rust code (e.g., for testing it).
 [`PyCell`](https://pyo3.rs/master/doc/pyo3/pycell/struct.PyCell.html) is our primary interface for that.
 
 `PyCell<T: PyClass>` is always allocated in the Python heap, so we don't have the ownership of it.
-We can get `&PyCell<T>`, not `PyCell<T>`.
+We can only get `&PyCell<T>`, not `PyCell<T>`.
 
 Thus, to mutate data behind `&PyCell` safely, we employ the
 [Interior Mutability Pattern](https://doc.rust-lang.org/book/ch15-05-interior-mutability.html)
@@ -242,8 +242,10 @@ baseclass of `T`.
 But for more deeply nested inheritance, you have to return `PyClassInitializer<T>`
 explicitly.
 
-To get a parent class from child, use `PyRef<T>` instead of `&self`,
+To get a parent class from a child, use `PyRef<T>` instead of `&self`,
 or `PyRefMut<T>` instead of `&mut self`.
+Then you can access a parent class by `self_.as_ref()` as `&Self::BaseClass`,
+or by `self_.into_super()` as `PyRef<Self::BaseClass>`.
 
 ```rust
 # use pyo3::prelude::*;
@@ -311,12 +313,6 @@ impl SubSubClass {
 # pyo3::py_run!(py, subsub, "assert subsub.method3() == 3000")
 ```
 
-To access the super class, you can use either of these two ways:
-- Use `self_: &PyCell<Self>` instead of `self`, and call `get_super()`
-- `ObjectProtocol::get_base`
-We recommend `PyCell` here, since it makes the context much clearer.
-
-
 If `SubClass` does not provide a baseclass initialization, the compilation fails.
 ```compile_fail
 # use pyo3::prelude::*;

pyo3-derive-backend/src/method.rs

@@ -29,9 +29,9 @@ pub enum FnType {
     FnCall,
     FnClass,
     FnStatic,
-    // self_: &PyCell<Self>,
+    /// For methods taht have `self_: &PyCell<Self>` instead of self receiver
     PySelfRef(syn::TypeReference),
-    // self_: PyRef<Self> or PyRefMut<Self>
+    /// For methods taht have `self_: PyRef<Self>` or `PyRefMut<Self>` instead of self receiver
     PySelfPath(syn::TypePath),
 }
 

src/objectprotocol.rs

@@ -5,8 +5,8 @@ use crate::err::{self, PyDowncastError, PyErr, PyResult};
 use crate::exceptions::TypeError;
 use crate::types::{PyAny, PyDict, PyIterator, PyString, PyTuple, PyType};
 use crate::{
-    ffi, AsPyPointer, FromPyObject, FromPyPointer, IntoPy, IntoPyPointer, Py, PyNativeType,
-    PyObject, PyTryFrom, PyTypeInfo, Python, ToBorrowedObject, ToPyObject,
+    ffi, AsPyPointer, FromPyObject, IntoPy, IntoPyPointer, Py, PyNativeType, PyObject, PyTryFrom,
+    Python, ToBorrowedObject, ToPyObject,
 };
 use std::cmp::Ordering;
 use std::os::raw::c_int;
@@ -170,12 +170,6 @@ pub trait ObjectProtocol {
     /// Gets the Python type pointer for this object.
     fn get_type_ptr(&self) -> *mut ffi::PyTypeObject;
 
-    /// Gets the Python base object for this object.
-    fn get_base(&self) -> &<Self as PyTypeInfo>::BaseType
-    where
-        Self: PyTypeInfo,
-        <Self as PyTypeInfo>::BaseType: for<'py> FromPyPointer<'py>;
-
     /// Casts the PyObject to a concrete Python object type.
     fn cast_as<'a, D>(&'a self) -> Result<&'a D, PyDowncastError>
     where
@@ -445,14 +439,6 @@ where
         unsafe { (*self.as_ptr()).ob_type }
     }
 
-    fn get_base(&self) -> &<Self as PyTypeInfo>::BaseType
-    where
-        Self: PyTypeInfo,
-        <Self as PyTypeInfo>::BaseType: for<'py> FromPyPointer<'py>,
-    {
-        unsafe { self.py().from_borrowed_ptr(self.as_ptr()) }
-    }
-
     fn cast_as<'a, D>(&'a self) -> Result<&'a D, PyDowncastError>
     where
         D: PyTryFrom<'a>,