Simplify impl PyTypeInfo for SliceBox

Author: kngwyu

src/slice_box.rs

@@ -2,6 +2,8 @@ use crate::types::TypeNum;
 use pyo3::{ffi, typeob, types::PyObjectRef, PyObjectAlloc, Python, ToPyPointer};
 use std::os::raw::c_void;
 
+/// It's a memory store for IntoPyArray.
+/// See IntoPyArray's doc for what concretely this type is for.
 #[repr(C)]
 pub(crate) struct SliceBox<T> {
     ob_base: ffi::PyObject,
@@ -28,9 +30,9 @@ impl<T> typeob::PyTypeInfo for SliceBox<T> {
     type Type = ();
     type BaseType = PyObjectRef;
     const NAME: &'static str = "SliceBox";
-    const DESCRIPTION: &'static str = "Memory store for PyArray made by IntoPyArray.";
+    const DESCRIPTION: &'static str = "Memory store for PyArray using rust's Box<[T]>.";
     const FLAGS: usize = 0;
-    const SIZE: usize = { Self::OFFSET as usize + std::mem::size_of::<Self>() + 0 + 0 };
+    const SIZE: usize = std::mem::size_of::<Self>();
     const OFFSET: isize = 0;
     #[inline]
     unsafe fn type_object() -> &'static mut ffi::PyTypeObject {