Merge pull request RustPython#3728 from rng-dynamics/object-sizeof

Add `object.__sizeof__`

Author: youknowone

derive/src/pyclass.rs

@@ -210,6 +210,7 @@ fn generate_class_def(
         Some(v) => quote!(Some(#v) ),
         None => quote!(None),
     };
+    let basicsize = quote!(std::mem::size_of::<#ident>());
     let is_pystruct = attrs.iter().any(|attr| {
         path_eq(&attr.path, "derive")
             && if let Ok(Meta::List(l)) = attr.parse_meta() {
@@ -259,6 +260,7 @@ fn generate_class_def(
             const MODULE_NAME: Option<&'static str> = #module_name;
             const TP_NAME: &'static str = #module_class_name;
             const DOC: Option<&'static str> = #doc;
+            const BASICSIZE: usize = #basicsize;
         }
 
         impl ::rustpython_vm::class::StaticType for #ident {

vm/src/builtins/object.rs

@@ -326,6 +326,11 @@ impl PyBaseObject {
     fn hash(zelf: PyObjectRef, vm: &VirtualMachine) -> PyResult<PyHash> {
         Self::slot_hash(&zelf, vm)
     }
+
+    #[pymethod(magic)]
+    fn sizeof(zelf: PyObjectRef) -> usize {
+        zelf.class().slots.basicsize
+    }
 }
 
 pub fn object_get_dict(obj: PyObjectRef, vm: &VirtualMachine) -> PyResult<PyDictRef> {

vm/src/class.rs

@@ -58,6 +58,7 @@ pub trait PyClassDef {
     const MODULE_NAME: Option<&'static str>;
     const TP_NAME: &'static str;
     const DOC: Option<&'static str> = None;
+    const BASICSIZE: usize;
 }
 
 impl<T> PyClassDef for PyRef<T>
@@ -68,6 +69,7 @@ where
     const MODULE_NAME: Option<&'static str> = T::MODULE_NAME;
     const TP_NAME: &'static str = T::TP_NAME;
     const DOC: Option<&'static str> = T::DOC;
+    const BASICSIZE: usize = T::BASICSIZE;
 }
 
 pub trait PyClassImpl: PyClassDef {
@@ -125,6 +127,7 @@ pub trait PyClassImpl: PyClassDef {
         let mut slots = PyTypeSlots {
             flags: Self::TP_FLAGS,
             name: PyRwLock::new(Some(Self::TP_NAME.to_owned())),
+            basicsize: Self::BASICSIZE,
             doc: Self::DOC,
             ..Default::default()
         };

vm/src/types/slot.rs

@@ -23,7 +23,9 @@ use std::{
 #[non_exhaustive]
 pub struct PyTypeSlots {
     pub name: PyRwLock<Option<String>>, // tp_name, not class name
-    // tp_basicsize, tp_itemsize
+
+    pub basicsize: usize,
+    // tp_itemsize
 
     // Methods to implement standard operations