diff --git a/vm/src/obj/objbytearray.rs b/vm/src/obj/objbytearray.rs
index 16758a438..6f78ecf48 100644
--- a/vm/src/obj/objbytearray.rs
+++ b/vm/src/obj/objbytearray.rs
@@ -7,7 +7,7 @@ use std::ops::{Deref, DerefMut};
 use num_traits::ToPrimitive;
 
 use crate::function::OptionalArg;
-use crate::pyobject::{PyContext, PyObjectRef, PyRef, PyResult, PyValue};
+use crate::pyobject::{PyClassImpl, PyContext, PyObjectRef, PyRef, PyResult, PyValue};
 use crate::vm::VirtualMachine;
 
 use super::objint;
@@ -84,11 +84,7 @@ pub fn init(context: &PyContext) {
         "upper" => context.new_rustfunc(PyByteArrayRef::upper)
     });
 
-    let bytearrayiterator_type = &context.bytearrayiterator_type;
-    extend_class!(context, bytearrayiterator_type, {
-        "__next__" => context.new_rustfunc(PyByteArrayIteratorRef::next),
-        "__iter__" => context.new_rustfunc(PyByteArrayIteratorRef::iter),
-    });
+    PyByteArrayIterator::extend_class(context, &context.bytearrayiterator_type);
 }
 
 fn bytearray_new(
@@ -287,6 +283,7 @@ mod tests {
     }
 }
 
+#[pyclass]
 #[derive(Debug)]
 pub struct PyByteArrayIterator {
     position: Cell<usize>,
@@ -299,10 +296,10 @@ impl PyValue for PyByteArrayIterator {
     }
 }
 
-type PyByteArrayIteratorRef = PyRef<PyByteArrayIterator>;
-
-impl PyByteArrayIteratorRef {
-    fn next(self, vm: &VirtualMachine) -> PyResult<u8> {
+#[pyimpl]
+impl PyByteArrayIterator {
+    #[pymethod(name = "__next__")]
+    fn next(&self, vm: &VirtualMachine) -> PyResult<u8> {
         if self.position.get() < self.bytearray.value.borrow().len() {
             let ret = self.bytearray.value.borrow()[self.position.get()];
             self.position.set(self.position.get() + 1);
@@ -312,7 +309,8 @@ impl PyByteArrayIteratorRef {
         }
     }
 
-    fn iter(self, _vm: &VirtualMachine) -> Self {
-        self
+    #[pymethod(name = "__iter__")]
+    fn iter(zelf: PyRef<Self>, _vm: &VirtualMachine) -> PyRef<Self> {
+        zelf
     }
 }
diff --git a/vm/src/obj/objbytes.rs b/vm/src/obj/objbytes.rs
index 0556de053..df9795902 100644
--- a/vm/src/obj/objbytes.rs
+++ b/vm/src/obj/objbytes.rs
@@ -64,11 +64,7 @@ pub fn init(context: &PyContext) {
     extend_class!(context, bytes_type, {
     "fromhex" => context.new_rustfunc(PyBytesRef::fromhex),
     });
-    let bytesiterator_type = &context.bytesiterator_type;
-    extend_class!(context, bytesiterator_type, {
-    "__next__" => context.new_rustfunc(PyBytesIteratorRef::next),
-    "__iter__" => context.new_rustfunc(PyBytesIteratorRef::iter),
-    });
+    PyBytesIterator::extend_class(context, &context.bytesiterator_type);
 }
 
 #[pyimpl]
@@ -271,6 +267,7 @@ impl PyBytesRef {
     }
 }
 
+#[pyclass]
 #[derive(Debug)]
 pub struct PyBytesIterator {
     position: Cell<usize>,
@@ -283,10 +280,10 @@ impl PyValue for PyBytesIterator {
     }
 }
 
-type PyBytesIteratorRef = PyRef<PyBytesIterator>;
-
-impl PyBytesIteratorRef {
-    fn next(self, vm: &VirtualMachine) -> PyResult<u8> {
+#[pyimpl]
+impl PyBytesIterator {
+    #[pymethod(name = "__next__")]
+    fn next(&self, vm: &VirtualMachine) -> PyResult<u8> {
         if self.position.get() < self.bytes.inner.len() {
             let ret = self.bytes[self.position.get()];
             self.position.set(self.position.get() + 1);
@@ -296,7 +293,8 @@ impl PyBytesIteratorRef {
         }
     }
 
-    fn iter(self, _vm: &VirtualMachine) -> Self {
-        self
+    #[pymethod(name = "__iter__")]
+    fn iter(zelf: PyRef<Self>, _vm: &VirtualMachine) -> PyRef<Self> {
+        zelf
     }
 }
diff --git a/vm/src/obj/objenumerate.rs b/vm/src/obj/objenumerate.rs
index c94aeabbd..56d232272 100644
--- a/vm/src/obj/objenumerate.rs
+++ b/vm/src/obj/objenumerate.rs
@@ -5,13 +5,14 @@ use num_bigint::BigInt;
 use num_traits::Zero;
 
 use crate::function::OptionalArg;
-use crate::pyobject::{PyContext, PyObjectRef, PyRef, PyResult, PyValue};
+use crate::pyobject::{PyClassImpl, PyContext, PyObjectRef, PyRef, PyResult, PyValue};
 use crate::vm::VirtualMachine;
 
 use super::objint::PyIntRef;
 use super::objiter;
 use super::objtype::PyClassRef;
 
+#[pyclass]
 #[derive(Debug)]
 pub struct PyEnumerate {
     counter: RefCell<BigInt>,
@@ -44,8 +45,10 @@ fn enumerate_new(
     .into_ref_with_type(vm, cls)
 }
 
-impl PyEnumerateRef {
-    fn next(self, vm: &VirtualMachine) -> PyResult {
+#[pyimpl]
+impl PyEnumerate {
+    #[pymethod(name = "__next__")]
+    fn next(&self, vm: &VirtualMachine) -> PyResult {
         let iterator = &self.iterator;
         let counter = &self.counter;
         let next_obj = objiter::call_next(vm, iterator)?;
@@ -58,16 +61,15 @@ impl PyEnumerateRef {
         Ok(result)
     }
 
-    fn iter(self, _vm: &VirtualMachine) -> Self {
-        self
+    #[pymethod(name = "__iter__")]
+    fn iter(zelf: PyRef<Self>, _vm: &VirtualMachine) -> PyRef<Self> {
+        zelf
     }
 }
 
 pub fn init(context: &PyContext) {
-    let enumerate_type = &context.enumerate_type;
-    extend_class!(context, enumerate_type, {
+    PyEnumerate::extend_class(context, &context.enumerate_type);
+    extend_class!(context, &context.enumerate_type, {
         "__new__" => context.new_rustfunc(enumerate_new),
-        "__next__" => context.new_rustfunc(PyEnumerateRef::next),
-        "__iter__" => context.new_rustfunc(PyEnumerateRef::iter),
     });
 }
diff --git a/vm/src/obj/objfilter.rs b/vm/src/obj/objfilter.rs
index 858a0531a..24800d6aa 100644
--- a/vm/src/obj/objfilter.rs
+++ b/vm/src/obj/objfilter.rs
@@ -1,4 +1,4 @@
-use crate::pyobject::{IdProtocol, PyContext, PyObjectRef, PyRef, PyResult, PyValue};
+use crate::pyobject::{IdProtocol, PyClassImpl, PyContext, PyObjectRef, PyRef, PyResult, PyValue};
 use crate::vm::VirtualMachine; // Required for arg_check! to use isinstance
 
 use super::objbool;
@@ -7,6 +7,11 @@ use crate::obj::objtype::PyClassRef;
 
 pub type PyFilterRef = PyRef<PyFilter>;
 
+/// filter(function or None, iterable) --> filter object
+///
+/// Return an iterator yielding those items of iterable for which function(item)
+/// is true. If function is None, return the items that are true.
+#[pyclass]
 #[derive(Debug)]
 pub struct PyFilter {
     predicate: PyObjectRef,
@@ -34,8 +39,10 @@ fn filter_new(
     .into_ref_with_type(vm, cls)
 }
 
-impl PyFilterRef {
-    fn next(self, vm: &VirtualMachine) -> PyResult {
+#[pyimpl]
+impl PyFilter {
+    #[pymethod(name = "__next__")]
+    fn next(&self, vm: &VirtualMachine) -> PyResult {
         let predicate = &self.predicate;
         let iterator = &self.iterator;
         loop {
@@ -53,23 +60,15 @@ impl PyFilterRef {
         }
     }
 
-    fn iter(self, _vm: &VirtualMachine) -> Self {
-        self
+    #[pymethod(name = "__iter__")]
+    fn iter(zelf: PyRef<Self>, _vm: &VirtualMachine) -> PyRef<Self> {
+        zelf
     }
 }
 
 pub fn init(context: &PyContext) {
-    let filter_type = &context.filter_type;
-
-    let filter_doc =
-        "filter(function or None, iterable) --> filter object\n\n\
-         Return an iterator yielding those items of iterable for which function(item)\n\
-         is true. If function is None, return the items that are true.";
-
-    extend_class!(context, filter_type, {
+    PyFilter::extend_class(context, &context.filter_type);
+    extend_class!(context, &context.filter_type, {
         "__new__" => context.new_rustfunc(filter_new),
-        "__doc__" => context.new_str(filter_doc.to_string()),
-        "__next__" => context.new_rustfunc(PyFilterRef::next),
-        "__iter__" => context.new_rustfunc(PyFilterRef::iter),
     });
 }
diff --git a/vm/src/obj/objiter.rs b/vm/src/obj/objiter.rs
index 6e1dc1d06..efe672d62 100644
--- a/vm/src/obj/objiter.rs
+++ b/vm/src/obj/objiter.rs
@@ -4,7 +4,9 @@
 
 use std::cell::Cell;
 
-use crate::pyobject::{PyContext, PyObjectRef, PyRef, PyResult, PyValue, TypeProtocol};
+use crate::pyobject::{
+    PyClassImpl, PyContext, PyObjectRef, PyRef, PyResult, PyValue, TypeProtocol,
+};
 use crate::vm::VirtualMachine;
 
 use super::objtype;
@@ -75,6 +77,7 @@ pub fn new_stop_iteration(vm: &VirtualMachine) -> PyObjectRef {
     vm.new_exception(stop_iteration_type, "End of iterator".to_string())
 }
 
+#[pyclass]
 #[derive(Debug)]
 pub struct PySequenceIterator {
     pub position: Cell<usize>,
@@ -87,10 +90,10 @@ impl PyValue for PySequenceIterator {
     }
 }
 
-type PySequenceIteratorRef = PyRef<PySequenceIterator>;
-
-impl PySequenceIteratorRef {
-    fn next(self, vm: &VirtualMachine) -> PyResult {
+#[pyimpl]
+impl PySequenceIterator {
+    #[pymethod(name = "__next__")]
+    fn next(&self, vm: &VirtualMachine) -> PyResult {
         let number = vm.ctx.new_int(self.position.get());
         match vm.call_method(&self.obj, "__getitem__", vec![number]) {
             Ok(val) => {
@@ -105,16 +108,12 @@ impl PySequenceIteratorRef {
         }
     }
 
-    fn iter(self, _vm: &VirtualMachine) -> Self {
-        self
+    #[pymethod(name = "__iter__")]
+    fn iter(zelf: PyRef<Self>, _vm: &VirtualMachine) -> PyRef<Self> {
+        zelf
     }
 }
 
 pub fn init(context: &PyContext) {
-    let iter_type = &context.iter_type;
-
-    extend_class!(context, iter_type, {
-        "__next__" => context.new_rustfunc(PySequenceIteratorRef::next),
-        "__iter__" => context.new_rustfunc(PySequenceIteratorRef::iter),
-    });
+    PySequenceIterator::extend_class(context, &context.iter_type);
 }
diff --git a/vm/src/obj/objlist.rs b/vm/src/obj/objlist.rs
index 5c1bad5af..6b00b6828 100644
--- a/vm/src/obj/objlist.rs
+++ b/vm/src/obj/objlist.rs
@@ -8,7 +8,8 @@ use num_traits::{One, Signed, ToPrimitive, Zero};
 
 use crate::function::{OptionalArg, PyFuncArgs};
 use crate::pyobject::{
-    IdProtocol, PyContext, PyIterable, PyObjectRef, PyRef, PyResult, PyValue, TryFromObject,
+    IdProtocol, PyClassImpl, PyContext, PyIterable, PyObjectRef, PyRef, PyResult, PyValue,
+    TryFromObject,
 };
 use crate::vm::{ReprGuard, VirtualMachine};
 
@@ -776,6 +777,7 @@ fn list_sort(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
     Ok(vm.get_none())
 }
 
+#[pyclass]
 #[derive(Debug)]
 pub struct PyListIterator {
     pub position: Cell<usize>,
@@ -788,10 +790,10 @@ impl PyValue for PyListIterator {
     }
 }
 
-type PyListIteratorRef = PyRef<PyListIterator>;
-
-impl PyListIteratorRef {
-    fn next(self, vm: &VirtualMachine) -> PyResult {
+#[pyimpl]
+impl PyListIterator {
+    #[pymethod(name = "__next__")]
+    fn next(&self, vm: &VirtualMachine) -> PyResult {
         if self.position.get() < self.list.elements.borrow().len() {
             let ret = self.list.elements.borrow()[self.position.get()].clone();
             self.position.set(self.position.get() + 1);
@@ -801,8 +803,9 @@ impl PyListIteratorRef {
         }
     }
 
-    fn iter(self, _vm: &VirtualMachine) -> Self {
-        self
+    #[pymethod(name = "__iter__")]
+    fn iter(zelf: PyRef<Self>, _vm: &VirtualMachine) -> PyRef<Self> {
+        zelf
     }
 }
 
@@ -848,9 +851,5 @@ pub fn init(context: &PyContext) {
         "remove" => context.new_rustfunc(PyListRef::remove)
     });
 
-    let listiterator_type = &context.listiterator_type;
-    extend_class!(context, listiterator_type, {
-        "__next__" => context.new_rustfunc(PyListIteratorRef::next),
-        "__iter__" => context.new_rustfunc(PyListIteratorRef::iter),
-    });
+    PyListIterator::extend_class(context, &context.listiterator_type);
 }
diff --git a/vm/src/obj/objmap.rs b/vm/src/obj/objmap.rs
index 061f4179f..61fe67c0d 100644
--- a/vm/src/obj/objmap.rs
+++ b/vm/src/obj/objmap.rs
@@ -1,10 +1,15 @@
 use crate::function::Args;
-use crate::pyobject::{PyContext, PyObjectRef, PyRef, PyResult, PyValue};
+use crate::pyobject::{PyClassImpl, PyContext, PyObjectRef, PyRef, PyResult, PyValue};
 use crate::vm::VirtualMachine;
 
 use super::objiter;
 use super::objtype::PyClassRef;
 
+/// map(func, *iterables) --> map object
+///
+/// Make an iterator that computes the function using arguments from
+/// each of the iterables.  Stops when the shortest iterable is exhausted.
+#[pyclass]
 #[derive(Debug)]
 pub struct PyMap {
     mapper: PyObjectRef,
@@ -35,8 +40,10 @@ fn map_new(
     .into_ref_with_type(vm, cls.clone())
 }
 
-impl PyMapRef {
-    fn next(self, vm: &VirtualMachine) -> PyResult {
+#[pyimpl]
+impl PyMap {
+    #[pymethod(name = "__next__")]
+    fn next(&self, vm: &VirtualMachine) -> PyResult {
         let next_objs = self
             .iterators
             .iter()
@@ -47,22 +54,15 @@ impl PyMapRef {
         vm.invoke(self.mapper.clone(), next_objs)
     }
 
-    fn iter(self, _vm: &VirtualMachine) -> Self {
-        self
+    #[pymethod(name = "__iter__")]
+    fn iter(zelf: PyRef<Self>, _vm: &VirtualMachine) -> PyRef<Self> {
+        zelf
     }
 }
 
 pub fn init(context: &PyContext) {
-    let map_type = &context.map_type;
-
-    let map_doc = "map(func, *iterables) --> map object\n\n\
-                   Make an iterator that computes the function using arguments from\n\
-                   each of the iterables.  Stops when the shortest iterable is exhausted.";
-
-    extend_class!(context, map_type, {
+    PyMap::extend_class(context, &context.map_type);
+    extend_class!(context, &context.map_type, {
         "__new__" => context.new_rustfunc(map_new),
-        "__next__" => context.new_rustfunc(PyMapRef::next),
-        "__iter__" => context.new_rustfunc(PyMapRef::iter),
-        "__doc__" => context.new_str(map_doc.to_string())
     });
 }
diff --git a/vm/src/obj/objrange.rs b/vm/src/obj/objrange.rs
index d98e7491f..2a43579c5 100644
--- a/vm/src/obj/objrange.rs
+++ b/vm/src/obj/objrange.rs
@@ -6,7 +6,7 @@ use num_traits::{One, Signed, Zero};
 
 use crate::function::{OptionalArg, PyFuncArgs};
 use crate::pyobject::{
-    PyContext, PyObjectRef, PyRef, PyResult, PyValue, TryFromObject, TypeProtocol,
+    PyClassImpl, PyContext, PyObjectRef, PyRef, PyResult, PyValue, TryFromObject, TypeProtocol,
 };
 use crate::vm::VirtualMachine;
 
@@ -124,11 +124,7 @@ pub fn init(context: &PyContext) {
         "step" => context.new_property(PyRange::step),
     });
 
-    let rangeiterator_type = &context.rangeiterator_type;
-    extend_class!(context, rangeiterator_type, {
-        "__next__" => context.new_rustfunc(PyRangeIteratorRef::next),
-        "__iter__" => context.new_rustfunc(PyRangeIteratorRef::iter),
-    });
+    PyRangeIterator::extend_class(context, &context.rangeiterator_type);
 }
 
 type PyRangeRef = PyRef<PyRange>;
@@ -341,6 +337,7 @@ fn range_new(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
     Ok(range.into_object())
 }
 
+#[pyclass]
 #[derive(Debug)]
 pub struct PyRangeIterator {
     position: Cell<usize>,
@@ -353,10 +350,10 @@ impl PyValue for PyRangeIterator {
     }
 }
 
-type PyRangeIteratorRef = PyRef<PyRangeIterator>;
-
-impl PyRangeIteratorRef {
-    fn next(self, vm: &VirtualMachine) -> PyResult<BigInt> {
+#[pyimpl]
+impl PyRangeIterator {
+    #[pymethod(name = "__next__")]
+    fn next(&self, vm: &VirtualMachine) -> PyResult<BigInt> {
         let position = BigInt::from(self.position.get());
         if let Some(int) = self.range.get(&position) {
             self.position.set(self.position.get() + 1);
@@ -366,8 +363,9 @@ impl PyRangeIteratorRef {
         }
     }
 
-    fn iter(self, _vm: &VirtualMachine) -> Self {
-        self
+    #[pymethod(name = "__iter__")]
+    fn iter(zelf: PyRef<Self>, _vm: &VirtualMachine) -> PyRef<Self> {
+        zelf
     }
 }
 
diff --git a/vm/src/obj/objtuple.rs b/vm/src/obj/objtuple.rs
index 216945284..42999189f 100644
--- a/vm/src/obj/objtuple.rs
+++ b/vm/src/obj/objtuple.rs
@@ -3,7 +3,7 @@ use std::fmt;
 use std::hash::{Hash, Hasher};
 
 use crate::function::OptionalArg;
-use crate::pyobject::{IdProtocol, PyContext, PyObjectRef, PyRef, PyResult, PyValue};
+use crate::pyobject::{IdProtocol, PyClassImpl, PyContext, PyObjectRef, PyRef, PyResult, PyValue};
 use crate::vm::{ReprGuard, VirtualMachine};
 
 use super::objbool;
@@ -224,6 +224,7 @@ fn tuple_new(
     PyTuple::from(elements).into_ref_with_type(vm, cls)
 }
 
+#[pyclass]
 #[derive(Debug)]
 pub struct PyTupleIterator {
     position: Cell<usize>,
@@ -236,10 +237,10 @@ impl PyValue for PyTupleIterator {
     }
 }
 
-type PyTupleIteratorRef = PyRef<PyTupleIterator>;
-
-impl PyTupleIteratorRef {
-    fn next(self, vm: &VirtualMachine) -> PyResult {
+#[pyimpl]
+impl PyTupleIterator {
+    #[pymethod(name = "__next__")]
+    fn next(&self, vm: &VirtualMachine) -> PyResult {
         if self.position.get() < self.tuple.elements.borrow().len() {
             let ret = self.tuple.elements.borrow()[self.position.get()].clone();
             self.position.set(self.position.get() + 1);
@@ -249,8 +250,9 @@ impl PyTupleIteratorRef {
         }
     }
 
-    fn iter(self, _vm: &VirtualMachine) -> Self {
-        self
+    #[pymethod(name = "__iter__")]
+    fn iter(zelf: PyRef<Self>, _vm: &VirtualMachine) -> PyRef<Self> {
+        zelf
     }
 }
 
@@ -282,9 +284,5 @@ If the argument is a tuple, the return value is the same object.";
         "index" => context.new_rustfunc(PyTupleRef::index)
     });
 
-    let tupleiterator_type = &context.tupleiterator_type;
-    extend_class!(context, tupleiterator_type, {
-        "__next__" => context.new_rustfunc(PyTupleIteratorRef::next),
-        "__iter__" => context.new_rustfunc(PyTupleIteratorRef::iter),
-    });
+    PyTupleIterator::extend_class(context, &context.tupleiterator_type);
 }
diff --git a/vm/src/obj/objzip.rs b/vm/src/obj/objzip.rs
index 81640a724..d9c577aa0 100644
--- a/vm/src/obj/objzip.rs
+++ b/vm/src/obj/objzip.rs
@@ -1,5 +1,5 @@
 use crate::function::Args;
-use crate::pyobject::{PyContext, PyObjectRef, PyRef, PyResult, PyValue};
+use crate::pyobject::{PyClassImpl, PyContext, PyObjectRef, PyRef, PyResult, PyValue};
 use crate::vm::VirtualMachine;
 
 use super::objiter;
@@ -7,6 +7,7 @@ use crate::obj::objtype::PyClassRef;
 
 pub type PyZipRef = PyRef<PyZip>;
 
+#[pyclass]
 #[derive(Debug)]
 pub struct PyZip {
     iterators: Vec<PyObjectRef>,
@@ -26,8 +27,10 @@ fn zip_new(cls: PyClassRef, iterables: Args, vm: &VirtualMachine) -> PyResult<Py
     PyZip { iterators }.into_ref_with_type(vm, cls)
 }
 
-impl PyZipRef {
-    fn next(self, vm: &VirtualMachine) -> PyResult {
+#[pyimpl]
+impl PyZip {
+    #[pymethod(name = "__next__")]
+    fn next(&self, vm: &VirtualMachine) -> PyResult {
         if self.iterators.is_empty() {
             Err(objiter::new_stop_iteration(vm))
         } else {
@@ -41,16 +44,15 @@ impl PyZipRef {
         }
     }
 
-    fn iter(self, _vm: &VirtualMachine) -> Self {
-        self
+    #[pymethod(name = "__iter__")]
+    fn iter(zelf: PyRef<Self>, _vm: &VirtualMachine) -> PyRef<Self> {
+        zelf
     }
 }
 
 pub fn init(context: &PyContext) {
-    let zip_type = &context.zip_type;
-    extend_class!(context, zip_type, {
+    PyZip::extend_class(context, &context.zip_type);
+    extend_class!(context, &context.zip_type, {
         "__new__" => context.new_rustfunc(zip_new),
-        "__next__" => context.new_rustfunc(PyZipRef::next),
-        "__iter__" => context.new_rustfunc(PyZipRef::iter),
     });
 }
diff --git a/vm/src/stdlib/os.rs b/vm/src/stdlib/os.rs
index 6d81ca9c1..2b6c859eb 100644
--- a/vm/src/stdlib/os.rs
+++ b/vm/src/stdlib/os.rs
@@ -15,7 +15,7 @@ use crate::obj::objiter;
 use crate::obj::objstr;
 use crate::obj::objstr::PyStringRef;
 use crate::obj::objtype::PyClassRef;
-use crate::pyobject::{ItemProtocol, PyObjectRef, PyRef, PyResult, PyValue};
+use crate::pyobject::{ItemProtocol, PyClassImpl, PyObjectRef, PyRef, PyResult, PyValue};
 use crate::vm::VirtualMachine;
 
 #[cfg(unix)]
@@ -232,6 +232,7 @@ impl DirEntryRef {
     }
 }
 
+#[pyclass]
 #[derive(Debug)]
 struct ScandirIterator {
     entries: RefCell<fs::ReadDir>,
@@ -243,10 +244,10 @@ impl PyValue for ScandirIterator {
     }
 }
 
-type ScandirIteratorRef = PyRef<ScandirIterator>;
-
-impl ScandirIteratorRef {
-    fn next(self, vm: &VirtualMachine) -> PyResult {
+#[pyimpl]
+impl ScandirIterator {
+    #[pymethod(name = "__next__")]
+    fn next(&self, vm: &VirtualMachine) -> PyResult {
         match self.entries.borrow_mut().next() {
             Some(entry) => match entry {
                 Ok(entry) => Ok(DirEntry { entry }.into_ref(vm).into_object()),
@@ -256,8 +257,9 @@ impl ScandirIteratorRef {
         }
     }
 
-    fn iter(self, _vm: &VirtualMachine) -> Self {
-        self
+    #[pymethod(name = "__iter__")]
+    fn iter(zelf: PyRef<Self>, _vm: &VirtualMachine) -> PyRef<Self> {
+        zelf
     }
 }
 
@@ -418,10 +420,8 @@ pub fn make_module(vm: &VirtualMachine) -> PyObjectRef {
 
     let environ = _os_environ(vm);
 
-    let scandir_iter = py_class!(ctx, "ScandirIter", ctx.object(), {
-         "__iter__" => ctx.new_rustfunc(ScandirIteratorRef::iter),
-         "__next__" => ctx.new_rustfunc(ScandirIteratorRef::next),
-    });
+    let scandir_iter = ctx.new_class("ScandirIter", ctx.object());
+    ScandirIterator::extend_class(ctx, &scandir_iter);
 
     let dir_entry = py_class!(ctx, "DirEntry", ctx.object(), {
          "name" => ctx.new_property(DirEntryRef::name),