diff --git a/vm/src/builtins/memory.rs b/vm/src/builtins/memory.rs
index 81576b5985..0b944eb4ca 100644
--- a/vm/src/builtins/memory.rs
+++ b/vm/src/builtins/memory.rs
@@ -68,16 +68,6 @@ impl Constructor for PyMemoryView {
     }
 }
 
-#[pyclass(with(
-    Hashable,
-    Comparable,
-    AsBuffer,
-    AsMapping,
-    AsSequence,
-    Constructor,
-    Iterable,
-    Representable
-))]
 impl PyMemoryView {
     fn parse_format(format: &str, vm: &VirtualMachine) -> PyResult<FormatSpec> {
         FormatSpec::parse(format.as_bytes(), vm)
@@ -143,13 +133,6 @@ impl PyMemoryView {
         zelf
     }
 
-    #[pymethod]
-    pub fn release(&self) {
-        if self.released.compare_exchange(false, true).is_ok() {
-            self.buffer.release();
-        }
-    }
-
     fn try_not_released(&self, vm: &VirtualMachine) -> PyResult<()> {
         if self.released.load() {
             Err(vm.new_value_error("operation forbidden on released memoryview object".to_owned()))
@@ -158,100 +141,6 @@ impl PyMemoryView {
         }
     }
 
-    #[pygetset]
-    fn obj(&self, vm: &VirtualMachine) -> PyResult<PyObjectRef> {
-        self.try_not_released(vm).map(|_| self.buffer.obj.clone())
-    }
-
-    #[pygetset]
-    fn nbytes(&self, vm: &VirtualMachine) -> PyResult<usize> {
-        self.try_not_released(vm).map(|_| self.desc.len)
-    }
-
-    #[pygetset]
-    fn readonly(&self, vm: &VirtualMachine) -> PyResult<bool> {
-        self.try_not_released(vm).map(|_| self.desc.readonly)
-    }
-
-    #[pygetset]
-    fn itemsize(&self, vm: &VirtualMachine) -> PyResult<usize> {
-        self.try_not_released(vm).map(|_| self.desc.itemsize)
-    }
-
-    #[pygetset]
-    fn ndim(&self, vm: &VirtualMachine) -> PyResult<usize> {
-        self.try_not_released(vm).map(|_| self.desc.ndim())
-    }
-
-    #[pygetset]
-    fn shape(&self, vm: &VirtualMachine) -> PyResult<PyTupleRef> {
-        self.try_not_released(vm)?;
-        Ok(vm.ctx.new_tuple(
-            self.desc
-                .dim_desc
-                .iter()
-                .map(|(shape, _, _)| shape.to_pyobject(vm))
-                .collect(),
-        ))
-    }
-
-    #[pygetset]
-    fn strides(&self, vm: &VirtualMachine) -> PyResult<PyTupleRef> {
-        self.try_not_released(vm)?;
-        Ok(vm.ctx.new_tuple(
-            self.desc
-                .dim_desc
-                .iter()
-                .map(|(_, stride, _)| stride.to_pyobject(vm))
-                .collect(),
-        ))
-    }
-
-    #[pygetset]
-    fn suboffsets(&self, vm: &VirtualMachine) -> PyResult<PyTupleRef> {
-        self.try_not_released(vm)?;
-        Ok(vm.ctx.new_tuple(
-            self.desc
-                .dim_desc
-                .iter()
-                .map(|(_, _, suboffset)| suboffset.to_pyobject(vm))
-                .collect(),
-        ))
-    }
-
-    #[pygetset]
-    fn format(&self, vm: &VirtualMachine) -> PyResult<PyStr> {
-        self.try_not_released(vm)
-            .map(|_| PyStr::from(self.desc.format.clone()))
-    }
-
-    #[pygetset]
-    fn contiguous(&self, vm: &VirtualMachine) -> PyResult<bool> {
-        self.try_not_released(vm).map(|_| self.desc.is_contiguous())
-    }
-
-    #[pygetset]
-    fn c_contiguous(&self, vm: &VirtualMachine) -> PyResult<bool> {
-        self.try_not_released(vm).map(|_| self.desc.is_contiguous())
-    }
-
-    #[pygetset]
-    fn f_contiguous(&self, vm: &VirtualMachine) -> PyResult<bool> {
-        // TODO: fortain order
-        self.try_not_released(vm)
-            .map(|_| self.desc.ndim() <= 1 && self.desc.is_contiguous())
-    }
-
-    #[pymethod(magic)]
-    fn enter(zelf: PyRef<Self>, vm: &VirtualMachine) -> PyResult<PyRef<Self>> {
-        zelf.try_not_released(vm).map(|_| zelf)
-    }
-
-    #[pymethod(magic)]
-    fn exit(&self, _args: FuncArgs) {
-        self.release();
-    }
-
     fn getitem_by_idx(&self, i: isize, vm: &VirtualMachine) -> PyResult {
         if self.desc.ndim() != 1 {
             return Err(vm.new_not_implemented_error(
@@ -281,29 +170,6 @@ impl PyMemoryView {
         format_unpack(&self.format_spec, &bytes[pos..pos + self.desc.itemsize], vm)
     }
 
-    #[pymethod(magic)]
-    fn getitem(zelf: PyRef<Self>, needle: PyObjectRef, vm: &VirtualMachine) -> PyResult {
-        zelf.try_not_released(vm)?;
-        if zelf.desc.ndim() == 0 {
-            // 0-d memoryview can be referenced using mv[...] or mv[()] only
-            if needle.is(&vm.ctx.ellipsis) {
-                return Ok(zelf.into());
-            }
-            if let Some(tuple) = needle.payload::<PyTuple>() {
-                if tuple.is_empty() {
-                    return zelf.unpack_single(0, vm);
-                }
-            }
-            return Err(vm.new_type_error("invalid indexing of 0-dim memory".to_owned()));
-        }
-
-        match SubscriptNeedle::try_from_object(vm, needle)? {
-            SubscriptNeedle::Index(i) => zelf.getitem_by_idx(i, vm),
-            SubscriptNeedle::Slice(slice) => zelf.getitem_by_slice(&slice, vm),
-            SubscriptNeedle::MultiIndex(indices) => zelf.getitem_by_multi_idx(&indices, vm),
-        }
-    }
-
     fn setitem_by_idx(&self, i: isize, value: PyObjectRef, vm: &VirtualMachine) -> PyResult<()> {
         if self.desc.ndim() != 1 {
             return Err(vm.new_not_implemented_error("sub-views are not implemented".to_owned()));
@@ -317,60 +183,6 @@ impl PyMemoryView {
         self.pack_single(pos, value, vm)
     }
 
-    fn setitem_by_slice(
-        zelf: PyRef<Self>,
-        slice: &PySlice,
-        src: PyObjectRef,
-        vm: &VirtualMachine,
-    ) -> PyResult<()> {
-        if zelf.desc.ndim() != 1 {
-            return Err(vm.new_not_implemented_error("sub-view are not implemented".to_owned()));
-        }
-
-        let mut dest = zelf.new_view();
-        dest.init_slice(slice, 0, vm)?;
-        dest.init_len();
-
-        if zelf.is(&src) {
-            return if !is_equiv_structure(&zelf.desc, &dest.desc) {
-                Err(vm.new_value_error(
-                    "memoryview assignment: lvalue and rvalue have different structures".to_owned(),
-                ))
-            } else {
-                // assign self[:] to self
-                Ok(())
-            };
-        };
-
-        let src = if let Some(src) = src.downcast_ref::<PyMemoryView>() {
-            if zelf.buffer.obj.is(&src.buffer.obj) {
-                src.to_contiguous(vm)
-            } else {
-                AsBuffer::as_buffer(src, vm)?
-            }
-        } else {
-            PyBuffer::try_from_object(vm, src)?
-        };
-
-        if !is_equiv_structure(&src.desc, &dest.desc) {
-            return Err(vm.new_value_error(
-                "memoryview assignment: lvalue and rvalue have different structures".to_owned(),
-            ));
-        }
-
-        let mut bytes_mut = dest.buffer.obj_bytes_mut();
-        let src_bytes = src.obj_bytes();
-        dest.desc.zip_eq(&src.desc, true, |a_range, b_range| {
-            let a_range = (a_range.start + dest.start as isize) as usize
-                ..(a_range.end + dest.start as isize) as usize;
-            let b_range = b_range.start as usize..b_range.end as usize;
-            bytes_mut[a_range].copy_from_slice(&src_bytes[b_range]);
-            false
-        });
-
-        Ok(())
-    }
-
     fn setitem_by_multi_idx(
         &self,
         indexes: &[isize],
@@ -381,47 +193,6 @@ impl PyMemoryView {
         self.pack_single(pos, value, vm)
     }
 
-    #[pymethod(magic)]
-    fn delitem(&self, _needle: PyObjectRef, vm: &VirtualMachine) -> PyResult<()> {
-        if self.desc.readonly {
-            return Err(vm.new_type_error("cannot modify read-only memory".to_owned()));
-        }
-        Err(vm.new_type_error("cannot delete memory".to_owned()))
-    }
-
-    #[pymethod(magic)]
-    fn setitem(
-        zelf: PyRef<Self>,
-        needle: PyObjectRef,
-        value: PyObjectRef,
-        vm: &VirtualMachine,
-    ) -> PyResult<()> {
-        zelf.try_not_released(vm)?;
-        if zelf.desc.readonly {
-            return Err(vm.new_type_error("cannot modify read-only memory".to_owned()));
-        }
-        if value.is(&vm.ctx.none) {
-            return Err(vm.new_type_error("cannot delete memory".to_owned()));
-        }
-
-        if zelf.desc.ndim() == 0 {
-            // TODO: merge branches when we got conditional if let
-            if needle.is(&vm.ctx.ellipsis) {
-                return zelf.pack_single(0, value, vm);
-            } else if let Some(tuple) = needle.payload::<PyTuple>() {
-                if tuple.is_empty() {
-                    return zelf.pack_single(0, value, vm);
-                }
-            }
-            return Err(vm.new_type_error("invalid indexing of 0-dim memory".to_owned()));
-        }
-        match SubscriptNeedle::try_from_object(vm, needle)? {
-            SubscriptNeedle::Index(i) => zelf.setitem_by_idx(i, value, vm),
-            SubscriptNeedle::Slice(slice) => Self::setitem_by_slice(zelf, &slice, value, vm),
-            SubscriptNeedle::MultiIndex(indices) => zelf.setitem_by_multi_idx(&indices, value, vm),
-        }
-    }
-
     fn pack_single(&self, pos: usize, value: PyObjectRef, vm: &VirtualMachine) -> PyResult<()> {
         let mut bytes = self.buffer.obj_bytes_mut();
         // TODO: Optimize
@@ -522,26 +293,6 @@ impl PyMemoryView {
         Ok(())
     }
 
-    /// return the length of the first dimension
-    #[pymethod(magic)]
-    fn len(&self, vm: &VirtualMachine) -> PyResult<usize> {
-        self.try_not_released(vm)?;
-        Ok(if self.desc.ndim() == 0 {
-            1
-        } else {
-            // shape for dim[0]
-            self.desc.dim_desc[0].0
-        })
-    }
-
-    #[pymethod]
-    fn tobytes(&self, vm: &VirtualMachine) -> PyResult<PyBytesRef> {
-        self.try_not_released(vm)?;
-        let mut v = vec![];
-        self.append_to(&mut v);
-        Ok(PyBytes::from(v).into_ref(vm))
-    }
-
     fn _to_list(
         &self,
         bytes: &[u8],
@@ -572,6 +323,389 @@ impl PyMemoryView {
         Ok(vm.ctx.new_list(v))
     }
 
+    fn eq(zelf: &Py<Self>, other: &PyObject, vm: &VirtualMachine) -> PyResult<bool> {
+        if zelf.is(other) {
+            return Ok(true);
+        }
+        if zelf.released.load() {
+            return Ok(false);
+        }
+
+        if let Some(other) = other.payload::<Self>() {
+            if other.released.load() {
+                return Ok(false);
+            }
+        }
+
+        let other = match PyBuffer::try_from_borrowed_object(vm, other) {
+            Ok(buf) => buf,
+            Err(_) => return Ok(false),
+        };
+
+        if !is_equiv_shape(&zelf.desc, &other.desc) {
+            return Ok(false);
+        }
+
+        let a_itemsize = zelf.desc.itemsize;
+        let b_itemsize = other.desc.itemsize;
+        let a_format_spec = &zelf.format_spec;
+        let b_format_spec = &Self::parse_format(&other.desc.format, vm)?;
+
+        if zelf.desc.ndim() == 0 {
+            let a_val = format_unpack(a_format_spec, &zelf.buffer.obj_bytes()[..a_itemsize], vm)?;
+            let b_val = format_unpack(b_format_spec, &other.obj_bytes()[..b_itemsize], vm)?;
+            return vm.bool_eq(&a_val, &b_val);
+        }
+
+        // TODO: optimize cmp by format
+        let mut ret = Ok(true);
+        let a_bytes = zelf.buffer.obj_bytes();
+        let b_bytes = other.obj_bytes();
+        zelf.desc.zip_eq(&other.desc, false, |a_range, b_range| {
+            let a_range = (a_range.start + zelf.start as isize) as usize
+                ..(a_range.end + zelf.start as isize) as usize;
+            let b_range = b_range.start as usize..b_range.end as usize;
+            let a_val = match format_unpack(a_format_spec, &a_bytes[a_range], vm) {
+                Ok(val) => val,
+                Err(e) => {
+                    ret = Err(e);
+                    return true;
+                }
+            };
+            let b_val = match format_unpack(b_format_spec, &b_bytes[b_range], vm) {
+                Ok(val) => val,
+                Err(e) => {
+                    ret = Err(e);
+                    return true;
+                }
+            };
+            ret = vm.bool_eq(&a_val, &b_val);
+            if let Ok(b) = ret {
+                !b
+            } else {
+                true
+            }
+        });
+        ret
+    }
+
+    fn obj_bytes(&self) -> BorrowedValue<[u8]> {
+        if self.desc.is_contiguous() {
+            BorrowedValue::map(self.buffer.obj_bytes(), |x| {
+                &x[self.start..self.start + self.desc.len]
+            })
+        } else {
+            BorrowedValue::map(self.buffer.obj_bytes(), |x| &x[self.start..])
+        }
+    }
+
+    fn obj_bytes_mut(&self) -> BorrowedValueMut<[u8]> {
+        if self.desc.is_contiguous() {
+            BorrowedValueMut::map(self.buffer.obj_bytes_mut(), |x| {
+                &mut x[self.start..self.start + self.desc.len]
+            })
+        } else {
+            BorrowedValueMut::map(self.buffer.obj_bytes_mut(), |x| &mut x[self.start..])
+        }
+    }
+
+    fn as_contiguous(&self) -> Option<BorrowedValue<[u8]>> {
+        self.desc.is_contiguous().then(|| {
+            BorrowedValue::map(self.buffer.obj_bytes(), |x| {
+                &x[self.start..self.start + self.desc.len]
+            })
+        })
+    }
+
+    fn _as_contiguous_mut(&self) -> Option<BorrowedValueMut<[u8]>> {
+        self.desc.is_contiguous().then(|| {
+            BorrowedValueMut::map(self.buffer.obj_bytes_mut(), |x| {
+                &mut x[self.start..self.start + self.desc.len]
+            })
+        })
+    }
+
+    fn append_to(&self, buf: &mut Vec<u8>) {
+        if let Some(bytes) = self.as_contiguous() {
+            buf.extend_from_slice(&bytes);
+        } else {
+            buf.reserve(self.desc.len);
+            let bytes = &*self.buffer.obj_bytes();
+            self.desc.for_each_segment(true, |range| {
+                let start = (range.start + self.start as isize) as usize;
+                let end = (range.end + self.start as isize) as usize;
+                buf.extend_from_slice(&bytes[start..end]);
+            })
+        }
+    }
+
+    fn contiguous_or_collect<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
+        let borrowed;
+        let mut collected;
+        let v = if let Some(bytes) = self.as_contiguous() {
+            borrowed = bytes;
+            &*borrowed
+        } else {
+            collected = vec![];
+            self.append_to(&mut collected);
+            &collected
+        };
+        f(v)
+    }
+
+    /// clone data from memoryview
+    /// keep the shape, convert to contiguous
+    pub fn to_contiguous(&self, vm: &VirtualMachine) -> PyBuffer {
+        let mut data = vec![];
+        self.append_to(&mut data);
+
+        if self.desc.ndim() == 0 {
+            return VecBuffer::from(data)
+                .into_ref(vm)
+                .into_pybuffer_with_descriptor(self.desc.clone());
+        }
+
+        let mut dim_desc = self.desc.dim_desc.clone();
+        dim_desc.last_mut().unwrap().1 = self.desc.itemsize as isize;
+        dim_desc.last_mut().unwrap().2 = 0;
+        for i in (0..dim_desc.len() - 1).rev() {
+            dim_desc[i].1 = dim_desc[i + 1].1 * dim_desc[i + 1].0 as isize;
+            dim_desc[i].2 = 0;
+        }
+
+        let desc = BufferDescriptor {
+            len: self.desc.len,
+            readonly: self.desc.readonly,
+            itemsize: self.desc.itemsize,
+            format: self.desc.format.clone(),
+            dim_desc,
+        };
+
+        VecBuffer::from(data)
+            .into_ref(vm)
+            .into_pybuffer_with_descriptor(desc)
+    }
+}
+
+impl Py<PyMemoryView> {
+    fn setitem_by_slice(
+        &self,
+        slice: &PySlice,
+        src: PyObjectRef,
+        vm: &VirtualMachine,
+    ) -> PyResult<()> {
+        if self.desc.ndim() != 1 {
+            return Err(vm.new_not_implemented_error("sub-view are not implemented".to_owned()));
+        }
+
+        let mut dest = self.new_view();
+        dest.init_slice(slice, 0, vm)?;
+        dest.init_len();
+
+        if self.is(&src) {
+            return if !is_equiv_structure(&self.desc, &dest.desc) {
+                Err(vm.new_value_error(
+                    "memoryview assignment: lvalue and rvalue have different structures".to_owned(),
+                ))
+            } else {
+                // assign self[:] to self
+                Ok(())
+            };
+        };
+
+        let src = if let Some(src) = src.downcast_ref::<PyMemoryView>() {
+            if self.buffer.obj.is(&src.buffer.obj) {
+                src.to_contiguous(vm)
+            } else {
+                AsBuffer::as_buffer(src, vm)?
+            }
+        } else {
+            PyBuffer::try_from_object(vm, src)?
+        };
+
+        if !is_equiv_structure(&src.desc, &dest.desc) {
+            return Err(vm.new_value_error(
+                "memoryview assignment: lvalue and rvalue have different structures".to_owned(),
+            ));
+        }
+
+        let mut bytes_mut = dest.buffer.obj_bytes_mut();
+        let src_bytes = src.obj_bytes();
+        dest.desc.zip_eq(&src.desc, true, |a_range, b_range| {
+            let a_range = (a_range.start + dest.start as isize) as usize
+                ..(a_range.end + dest.start as isize) as usize;
+            let b_range = b_range.start as usize..b_range.end as usize;
+            bytes_mut[a_range].copy_from_slice(&src_bytes[b_range]);
+            false
+        });
+
+        Ok(())
+    }
+}
+
+#[pyclass(with(
+    Py,
+    Hashable,
+    Comparable,
+    AsBuffer,
+    AsMapping,
+    AsSequence,
+    Constructor,
+    Iterable,
+    Representable
+))]
+impl PyMemoryView {
+    #[pymethod]
+    pub fn release(&self) {
+        if self.released.compare_exchange(false, true).is_ok() {
+            self.buffer.release();
+        }
+    }
+
+    #[pygetset]
+    fn obj(&self, vm: &VirtualMachine) -> PyResult<PyObjectRef> {
+        self.try_not_released(vm).map(|_| self.buffer.obj.clone())
+    }
+
+    #[pygetset]
+    fn nbytes(&self, vm: &VirtualMachine) -> PyResult<usize> {
+        self.try_not_released(vm).map(|_| self.desc.len)
+    }
+
+    #[pygetset]
+    fn readonly(&self, vm: &VirtualMachine) -> PyResult<bool> {
+        self.try_not_released(vm).map(|_| self.desc.readonly)
+    }
+
+    #[pygetset]
+    fn itemsize(&self, vm: &VirtualMachine) -> PyResult<usize> {
+        self.try_not_released(vm).map(|_| self.desc.itemsize)
+    }
+
+    #[pygetset]
+    fn ndim(&self, vm: &VirtualMachine) -> PyResult<usize> {
+        self.try_not_released(vm).map(|_| self.desc.ndim())
+    }
+
+    #[pygetset]
+    fn shape(&self, vm: &VirtualMachine) -> PyResult<PyTupleRef> {
+        self.try_not_released(vm)?;
+        Ok(vm.ctx.new_tuple(
+            self.desc
+                .dim_desc
+                .iter()
+                .map(|(shape, _, _)| shape.to_pyobject(vm))
+                .collect(),
+        ))
+    }
+
+    #[pygetset]
+    fn strides(&self, vm: &VirtualMachine) -> PyResult<PyTupleRef> {
+        self.try_not_released(vm)?;
+        Ok(vm.ctx.new_tuple(
+            self.desc
+                .dim_desc
+                .iter()
+                .map(|(_, stride, _)| stride.to_pyobject(vm))
+                .collect(),
+        ))
+    }
+
+    #[pygetset]
+    fn suboffsets(&self, vm: &VirtualMachine) -> PyResult<PyTupleRef> {
+        self.try_not_released(vm)?;
+        Ok(vm.ctx.new_tuple(
+            self.desc
+                .dim_desc
+                .iter()
+                .map(|(_, _, suboffset)| suboffset.to_pyobject(vm))
+                .collect(),
+        ))
+    }
+
+    #[pygetset]
+    fn format(&self, vm: &VirtualMachine) -> PyResult<PyStr> {
+        self.try_not_released(vm)
+            .map(|_| PyStr::from(self.desc.format.clone()))
+    }
+
+    #[pygetset]
+    fn contiguous(&self, vm: &VirtualMachine) -> PyResult<bool> {
+        self.try_not_released(vm).map(|_| self.desc.is_contiguous())
+    }
+
+    #[pygetset]
+    fn c_contiguous(&self, vm: &VirtualMachine) -> PyResult<bool> {
+        self.try_not_released(vm).map(|_| self.desc.is_contiguous())
+    }
+
+    #[pygetset]
+    fn f_contiguous(&self, vm: &VirtualMachine) -> PyResult<bool> {
+        // TODO: fortain order
+        self.try_not_released(vm)
+            .map(|_| self.desc.ndim() <= 1 && self.desc.is_contiguous())
+    }
+
+    #[pymethod(magic)]
+    fn enter(zelf: PyRef<Self>, vm: &VirtualMachine) -> PyResult<PyRef<Self>> {
+        zelf.try_not_released(vm).map(|_| zelf)
+    }
+
+    #[pymethod(magic)]
+    fn exit(&self, _args: FuncArgs) {
+        self.release();
+    }
+
+    #[pymethod(magic)]
+    fn getitem(zelf: PyRef<Self>, needle: PyObjectRef, vm: &VirtualMachine) -> PyResult {
+        zelf.try_not_released(vm)?;
+        if zelf.desc.ndim() == 0 {
+            // 0-d memoryview can be referenced using mv[...] or mv[()] only
+            if needle.is(&vm.ctx.ellipsis) {
+                return Ok(zelf.into());
+            }
+            if let Some(tuple) = needle.payload::<PyTuple>() {
+                if tuple.is_empty() {
+                    return zelf.unpack_single(0, vm);
+                }
+            }
+            return Err(vm.new_type_error("invalid indexing of 0-dim memory".to_owned()));
+        }
+
+        match SubscriptNeedle::try_from_object(vm, needle)? {
+            SubscriptNeedle::Index(i) => zelf.getitem_by_idx(i, vm),
+            SubscriptNeedle::Slice(slice) => zelf.getitem_by_slice(&slice, vm),
+            SubscriptNeedle::MultiIndex(indices) => zelf.getitem_by_multi_idx(&indices, vm),
+        }
+    }
+
+    #[pymethod(magic)]
+    fn delitem(&self, _needle: PyObjectRef, vm: &VirtualMachine) -> PyResult<()> {
+        if self.desc.readonly {
+            return Err(vm.new_type_error("cannot modify read-only memory".to_owned()));
+        }
+        Err(vm.new_type_error("cannot delete memory".to_owned()))
+    }
+
+    #[pymethod(magic)]
+    fn len(&self, vm: &VirtualMachine) -> PyResult<usize> {
+        self.try_not_released(vm)?;
+        Ok(if self.desc.ndim() == 0 {
+            1
+        } else {
+            // shape for dim[0]
+            self.desc.dim_desc[0].0
+        })
+    }
+
+    #[pymethod]
+    fn tobytes(&self, vm: &VirtualMachine) -> PyResult<PyBytesRef> {
+        self.try_not_released(vm)?;
+        let mut v = vec![];
+        self.append_to(&mut v);
+        Ok(PyBytes::from(v).into_ref(vm))
+    }
+
     #[pymethod]
     fn tolist(&self, vm: &VirtualMachine) -> PyResult<PyListRef> {
         self.try_not_released(vm)?;
@@ -714,178 +848,51 @@ impl PyMemoryView {
             Ok(self.cast_to_1d(format, vm)?.into_ref(vm))
         }
     }
+}
 
-    fn eq(zelf: &Py<Self>, other: &PyObject, vm: &VirtualMachine) -> PyResult<bool> {
-        if zelf.is(other) {
-            return Ok(true);
-        }
-        if zelf.released.load() {
-            return Ok(false);
-        }
-
-        if let Some(other) = other.payload::<Self>() {
-            if other.released.load() {
-                return Ok(false);
-            }
-        }
-
-        let other = match PyBuffer::try_from_borrowed_object(vm, other) {
-            Ok(buf) => buf,
-            Err(_) => return Ok(false),
-        };
-
-        if !is_equiv_shape(&zelf.desc, &other.desc) {
-            return Ok(false);
-        }
-
-        let a_itemsize = zelf.desc.itemsize;
-        let b_itemsize = other.desc.itemsize;
-        let a_format_spec = &zelf.format_spec;
-        let b_format_spec = &Self::parse_format(&other.desc.format, vm)?;
-
-        if zelf.desc.ndim() == 0 {
-            let a_val = format_unpack(a_format_spec, &zelf.buffer.obj_bytes()[..a_itemsize], vm)?;
-            let b_val = format_unpack(b_format_spec, &other.obj_bytes()[..b_itemsize], vm)?;
-            return vm.bool_eq(&a_val, &b_val);
-        }
-
-        // TODO: optimize cmp by format
-        let mut ret = Ok(true);
-        let a_bytes = zelf.buffer.obj_bytes();
-        let b_bytes = other.obj_bytes();
-        zelf.desc.zip_eq(&other.desc, false, |a_range, b_range| {
-            let a_range = (a_range.start + zelf.start as isize) as usize
-                ..(a_range.end + zelf.start as isize) as usize;
-            let b_range = b_range.start as usize..b_range.end as usize;
-            let a_val = match format_unpack(a_format_spec, &a_bytes[a_range], vm) {
-                Ok(val) => val,
-                Err(e) => {
-                    ret = Err(e);
-                    return true;
-                }
-            };
-            let b_val = match format_unpack(b_format_spec, &b_bytes[b_range], vm) {
-                Ok(val) => val,
-                Err(e) => {
-                    ret = Err(e);
-                    return true;
-                }
-            };
-            ret = vm.bool_eq(&a_val, &b_val);
-            if let Ok(b) = ret {
-                !b
-            } else {
-                true
-            }
-        });
-        ret
-    }
-
+#[pyclass]
+impl Py<PyMemoryView> {
     #[pymethod(magic)]
-    fn reduce_ex(zelf: PyRef<Self>, _proto: usize, vm: &VirtualMachine) -> PyResult {
-        Self::reduce(zelf, vm)
-    }
-
-    #[pymethod(magic)]
-    fn reduce(_zelf: PyRef<Self>, vm: &VirtualMachine) -> PyResult {
-        Err(vm.new_type_error("cannot pickle 'memoryview' object".to_owned()))
-    }
-
-    fn obj_bytes(&self) -> BorrowedValue<[u8]> {
-        if self.desc.is_contiguous() {
-            BorrowedValue::map(self.buffer.obj_bytes(), |x| {
-                &x[self.start..self.start + self.desc.len]
-            })
-        } else {
-            BorrowedValue::map(self.buffer.obj_bytes(), |x| &x[self.start..])
+    fn setitem(
+        &self,
+        needle: PyObjectRef,
+        value: PyObjectRef,
+        vm: &VirtualMachine,
+    ) -> PyResult<()> {
+        self.try_not_released(vm)?;
+        if self.desc.readonly {
+            return Err(vm.new_type_error("cannot modify read-only memory".to_owned()));
         }
-    }
-
-    fn obj_bytes_mut(&self) -> BorrowedValueMut<[u8]> {
-        if self.desc.is_contiguous() {
-            BorrowedValueMut::map(self.buffer.obj_bytes_mut(), |x| {
-                &mut x[self.start..self.start + self.desc.len]
-            })
-        } else {
-            BorrowedValueMut::map(self.buffer.obj_bytes_mut(), |x| &mut x[self.start..])
+        if value.is(&vm.ctx.none) {
+            return Err(vm.new_type_error("cannot delete memory".to_owned()));
         }
-    }
-
-    fn as_contiguous(&self) -> Option<BorrowedValue<[u8]>> {
-        self.desc.is_contiguous().then(|| {
-            BorrowedValue::map(self.buffer.obj_bytes(), |x| {
-                &x[self.start..self.start + self.desc.len]
-            })
-        })
-    }
-
-    fn _as_contiguous_mut(&self) -> Option<BorrowedValueMut<[u8]>> {
-        self.desc.is_contiguous().then(|| {
-            BorrowedValueMut::map(self.buffer.obj_bytes_mut(), |x| {
-                &mut x[self.start..self.start + self.desc.len]
-            })
-        })
-    }
-
-    fn append_to(&self, buf: &mut Vec<u8>) {
-        if let Some(bytes) = self.as_contiguous() {
-            buf.extend_from_slice(&bytes);
-        } else {
-            buf.reserve(self.desc.len);
-            let bytes = &*self.buffer.obj_bytes();
-            self.desc.for_each_segment(true, |range| {
-                let start = (range.start + self.start as isize) as usize;
-                let end = (range.end + self.start as isize) as usize;
-                buf.extend_from_slice(&bytes[start..end]);
-            })
-        }
-    }
-
-    fn contiguous_or_collect<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
-        let borrowed;
-        let mut collected;
-        let v = if let Some(bytes) = self.as_contiguous() {
-            borrowed = bytes;
-            &*borrowed
-        } else {
-            collected = vec![];
-            self.append_to(&mut collected);
-            &collected
-        };
-        f(v)
-    }
-
-    /// clone data from memoryview
-    /// keep the shape, convert to contiguous
-    pub fn to_contiguous(&self, vm: &VirtualMachine) -> PyBuffer {
-        let mut data = vec![];
-        self.append_to(&mut data);
 
         if self.desc.ndim() == 0 {
-            return VecBuffer::from(data)
-                .into_ref(vm)
-                .into_pybuffer_with_descriptor(self.desc.clone());
+            // TODO: merge branches when we got conditional if let
+            if needle.is(&vm.ctx.ellipsis) {
+                return self.pack_single(0, value, vm);
+            } else if let Some(tuple) = needle.payload::<PyTuple>() {
+                if tuple.is_empty() {
+                    return self.pack_single(0, value, vm);
+                }
+            }
+            return Err(vm.new_type_error("invalid indexing of 0-dim memory".to_owned()));
         }
-
-        let mut dim_desc = self.desc.dim_desc.clone();
-        dim_desc.last_mut().unwrap().1 = self.desc.itemsize as isize;
-        dim_desc.last_mut().unwrap().2 = 0;
-        for i in (0..dim_desc.len() - 1).rev() {
-            dim_desc[i].1 = dim_desc[i + 1].1 * dim_desc[i + 1].0 as isize;
-            dim_desc[i].2 = 0;
+        match SubscriptNeedle::try_from_object(vm, needle)? {
+            SubscriptNeedle::Index(i) => self.setitem_by_idx(i, value, vm),
+            SubscriptNeedle::Slice(slice) => self.setitem_by_slice(&slice, value, vm),
+            SubscriptNeedle::MultiIndex(indices) => self.setitem_by_multi_idx(&indices, value, vm),
         }
+    }
 
-        let desc = BufferDescriptor {
-            len: self.desc.len,
-            readonly: self.desc.readonly,
-            itemsize: self.desc.itemsize,
-            format: self.desc.format.clone(),
-            dim_desc,
-        };
+    #[pymethod(magic)]
+    fn reduce_ex(&self, _proto: usize, vm: &VirtualMachine) -> PyResult {
+        self.reduce(vm)
+    }
 
-        VecBuffer::from(data)
-            .into_ref(vm)
-            .into_pybuffer_with_descriptor(desc)
+    #[pymethod(magic)]
+    fn reduce(&self, vm: &VirtualMachine) -> PyResult {
+        Err(vm.new_type_error("cannot pickle 'memoryview' object".to_owned()))
     }
 }
 
@@ -977,7 +984,7 @@ impl AsMapping for PyMemoryView {
             ass_subscript: atomic_func!(|mapping, needle, value, vm| {
                 let zelf = PyMemoryView::mapping_downcast(mapping);
                 if let Some(value) = value {
-                    PyMemoryView::setitem(zelf.to_owned(), needle.to_owned(), value, vm)
+                    zelf.setitem(needle.to_owned(), value, vm)
                 } else {
                     Err(vm.new_type_error("cannot delete memory".to_owned()))
                 }