lifetime bounded TryFromBorrwoedObject

examples/call_between_rust_and_python.rs

@@ -86,8 +86,8 @@ python_person.name: {}",
         name: String,
     }
 
-    impl TryFromBorrowedObject for PythonPerson {
-        fn try_from_borrowed_object(vm: &VirtualMachine, obj: &PyObject) -> PyResult<Self> {
+    impl<'a> TryFromBorrowedObject<'a> for PythonPerson {
+        fn try_from_borrowed_object(vm: &VirtualMachine, obj: &'a PyObject) -> PyResult<Self> {
             let name = obj.get_attr("name", vm)?.try_into_value::<String>(vm)?;
             Ok(PythonPerson { name })
         }

stdlib/src/mmap.rs

@@ -72,8 +72,8 @@ mod mmap {
         Copy = 3,
     }
 
-    impl TryFromBorrowedObject for AccessMode {
-        fn try_from_borrowed_object(vm: &VirtualMachine, obj: &PyObject) -> PyResult<Self> {
+    impl<'a> TryFromBorrowedObject<'a> for AccessMode {
+        fn try_from_borrowed_object(vm: &VirtualMachine, obj: &'a PyObject) -> PyResult<Self> {
             let i = u32::try_from_borrowed_object(vm, obj)?;
             Ok(match i {
                 0 => Self::Default,

stdlib/src/resource.rs

@@ -129,8 +129,8 @@ mod resource {
     }
 
     struct Limits(libc::rlimit);
-    impl TryFromBorrowedObject for Limits {
-        fn try_from_borrowed_object(vm: &VirtualMachine, obj: &PyObject) -> PyResult<Self> {
+    impl<'a> TryFromBorrowedObject<'a> for Limits {
+        fn try_from_borrowed_object(vm: &VirtualMachine, obj: &'a PyObject) -> PyResult<Self> {
             let seq: Vec<libc::rlim_t> = obj.try_to_value(vm)?;
             match *seq {
                 [cur, max] => Ok(Self(libc::rlimit {

stdlib/src/unicodedata.rs

@@ -41,8 +41,8 @@ enum NormalizeForm {
     Nfkd,
 }
 
-impl TryFromBorrowedObject for NormalizeForm {
-    fn try_from_borrowed_object(vm: &VirtualMachine, obj: &PyObject) -> PyResult<Self> {
+impl<'a> TryFromBorrowedObject<'a> for NormalizeForm {
+    fn try_from_borrowed_object(vm: &VirtualMachine, obj: &'a PyObject) -> PyResult<Self> {
         obj.try_value_with(
             |form: &PyStr| {
                 Ok(match form.as_str() {

stdlib/src/zlib.rs

@@ -581,8 +581,8 @@ mod zlib {
         }
     }
 
-    impl TryFromBorrowedObject for Level {
-        fn try_from_borrowed_object(vm: &VirtualMachine, obj: &PyObject) -> PyResult<Self> {
+    impl<'a> TryFromBorrowedObject<'a> for Level {
+        fn try_from_borrowed_object(vm: &VirtualMachine, obj: &'a PyObject) -> PyResult<Self> {
             let int: i32 = obj.try_index(vm)?.try_to_primitive(vm)?;
             Ok(Self::new(int))
         }

vm/src/builtins/bool.rs

@@ -19,8 +19,8 @@ impl ToPyObject for bool {
     }
 }
 
-impl TryFromBorrowedObject for bool {
-    fn try_from_borrowed_object(vm: &VirtualMachine, obj: &PyObject) -> PyResult<bool> {
+impl<'a> TryFromBorrowedObject<'a> for bool {
+    fn try_from_borrowed_object(vm: &VirtualMachine, obj: &'a PyObject) -> PyResult<bool> {
         if obj.fast_isinstance(vm.ctx.types.int_type) {
             Ok(get_value(obj))
         } else {

vm/src/builtins/bytes.rs

@@ -742,8 +742,8 @@ impl IterNext for PyBytesIterator {
     }
 }
 
-impl TryFromBorrowedObject for PyBytes {
-    fn try_from_borrowed_object(vm: &VirtualMachine, obj: &PyObject) -> PyResult<Self> {
+impl<'a> TryFromBorrowedObject<'a> for PyBytes {
+    fn try_from_borrowed_object(vm: &VirtualMachine, obj: &'a PyObject) -> PyResult<Self> {
         PyBytesInner::try_from_borrowed_object(vm, obj).map(|x| x.into())
     }
 }

vm/src/builtins/int.rs

@@ -72,8 +72,8 @@ impl_into_pyobject_int!(isize i8 i16 i32 i64 i128 usize u8 u16 u32 u64 u128 BigI
 
 macro_rules! impl_try_from_object_int {
     ($(($t:ty, $to_prim:ident),)*) => {$(
-        impl TryFromBorrowedObject for $t {
-            fn try_from_borrowed_object(vm: &VirtualMachine, obj: &PyObject) -> PyResult<Self> {
+        impl<'a> TryFromBorrowedObject<'a> for $t {
+            fn try_from_borrowed_object(vm: &VirtualMachine, obj: &'a PyObject) -> PyResult<Self> {
                 obj.try_value_with(|int: &PyInt| {
                     int.try_to_primitive(vm)
                 }, vm)

vm/src/builtins/str.rs

@@ -42,8 +42,8 @@ use unic_ucd_category::GeneralCategory;
 use unic_ucd_ident::{is_xid_continue, is_xid_start};
 use unicode_casing::CharExt;
 
-impl TryFromBorrowedObject for String {
-    fn try_from_borrowed_object(vm: &VirtualMachine, obj: &PyObject) -> PyResult<Self> {
+impl<'a> TryFromBorrowedObject<'a> for String {
+    fn try_from_borrowed_object(vm: &VirtualMachine, obj: &'a PyObject) -> PyResult<Self> {
         obj.try_value_with(|pystr: &PyStr| Ok(pystr.as_str().to_owned()), vm)
     }
 }

vm/src/bytesinner.rs

@@ -30,8 +30,8 @@ impl From<Vec<u8>> for PyBytesInner {
     }
 }
 
-impl TryFromBorrowedObject for PyBytesInner {
-    fn try_from_borrowed_object(vm: &VirtualMachine, obj: &PyObject) -> PyResult<Self> {
+impl<'a> TryFromBorrowedObject<'a> for PyBytesInner {
+    fn try_from_borrowed_object(vm: &VirtualMachine, obj: &'a PyObject) -> PyResult<Self> {
         bytes_from_object(vm, obj).map(Self::from)
     }
 }

vm/src/convert/try_from.rs

@@ -1,7 +1,7 @@
 use crate::{
     builtins::PyFloat,
     object::{AsObject, PyObject, PyObjectRef, PyPayload, PyRef, PyResult},
-    vm::VirtualMachine,
+    Py, VirtualMachine,
 };
 use num_traits::ToPrimitive;
 
@@ -15,7 +15,7 @@ pub trait TryFromObject: Sized {
 }
 
 /// Rust-side only version of TryFromObject to reduce unnecessary Rc::clone
-impl<T: TryFromBorrowedObject> TryFromObject for T {
+impl<T: for<'a> TryFromBorrowedObject<'a>> TryFromObject for T {
     fn try_from_object(vm: &VirtualMachine, obj: PyObjectRef) -> PyResult<Self> {
         TryFromBorrowedObject::try_from_borrowed_object(vm, &obj)
     }
@@ -31,9 +31,9 @@ impl PyObjectRef {
 }
 
 impl PyObject {
-    pub fn try_to_value<T>(&self, vm: &VirtualMachine) -> PyResult<T>
+    pub fn try_to_value<'a, T: 'a>(&'a self, vm: &VirtualMachine) -> PyResult<T>
     where
-        T: TryFromBorrowedObject,
+        T: TryFromBorrowedObject<'a>,
     {
         T::try_from_borrowed_object(vm, self)
     }
@@ -55,9 +55,12 @@ impl PyObject {
 }
 
 /// Lower-cost variation of `TryFromObject`
-pub trait TryFromBorrowedObject: Sized {
+pub trait TryFromBorrowedObject<'a>: Sized
+where
+    Self: 'a,
+{
     /// Attempt to convert a Python object to a value of this type.
-    fn try_from_borrowed_object(vm: &VirtualMachine, obj: &PyObject) -> PyResult<Self>;
+    fn try_from_borrowed_object(vm: &VirtualMachine, obj: &'a PyObject) -> PyResult<Self>;
 }
 
 impl<T> TryFromObject for PyRef<T>
@@ -93,12 +96,24 @@ impl<T: TryFromObject> TryFromObject for Option<T> {
     }
 }
 
-impl<T: TryFromObject> TryFromBorrowedObject for Vec<T> {
-    fn try_from_borrowed_object(vm: &VirtualMachine, value: &PyObject) -> PyResult<Self> {
+impl<'a, T: 'a + TryFromObject> TryFromBorrowedObject<'a> for Vec<T> {
+    fn try_from_borrowed_object(vm: &VirtualMachine, value: &'a PyObject) -> PyResult<Self> {
         vm.extract_elements_with(value, |obj| T::try_from_object(vm, obj))
     }
 }
 
+impl<'a, T: PyPayload> TryFromBorrowedObject<'a> for &'a Py<T> {
+    fn try_from_borrowed_object(vm: &VirtualMachine, obj: &'a PyObject) -> PyResult<Self> {
+        let class = T::class(vm);
+        if obj.fast_isinstance(class) {
+            obj.downcast_ref()
+                .ok_or_else(|| vm.new_downcast_runtime_error(class, &obj))
+        } else {
+            Err(vm.new_downcast_type_error(class, &obj))
+        }
+    }
+}
+
 impl TryFromObject for std::time::Duration {
     fn try_from_object(vm: &VirtualMachine, obj: PyObjectRef) -> PyResult<Self> {
         use std::time::Duration;

vm/src/function/buffer.rs

@@ -65,8 +65,8 @@ impl From<ArgBytesLike> for PyBuffer {
     }
 }
 
-impl TryFromBorrowedObject for ArgBytesLike {
-    fn try_from_borrowed_object(vm: &VirtualMachine, obj: &PyObject) -> PyResult<Self> {
+impl<'a> TryFromBorrowedObject<'a> for ArgBytesLike {
+    fn try_from_borrowed_object(vm: &VirtualMachine, obj: &'a PyObject) -> PyResult<Self> {
         let buffer = PyBuffer::try_from_borrowed_object(vm, obj)?;
         if buffer.desc.is_contiguous() {
             Ok(Self(buffer))
@@ -107,8 +107,8 @@ impl From<ArgMemoryBuffer> for PyBuffer {
     }
 }
 
-impl TryFromBorrowedObject for ArgMemoryBuffer {
-    fn try_from_borrowed_object(vm: &VirtualMachine, obj: &PyObject) -> PyResult<Self> {
+impl<'a> TryFromBorrowedObject<'a> for ArgMemoryBuffer {
+    fn try_from_borrowed_object(vm: &VirtualMachine, obj: &'a PyObject) -> PyResult<Self> {
         let buffer = PyBuffer::try_from_borrowed_object(vm, obj)?;
         if !buffer.desc.is_contiguous() {
             Err(vm.new_type_error("non-contiguous buffer is not a bytes-like object".to_owned()))

vm/src/function/mod.rs

@@ -28,8 +28,8 @@ pub enum ArgByteOrder {
     Little,
 }
 
-impl TryFromBorrowedObject for ArgByteOrder {
-    fn try_from_borrowed_object(vm: &VirtualMachine, obj: &PyObject) -> PyResult<Self> {
+impl<'a> TryFromBorrowedObject<'a> for ArgByteOrder {
+    fn try_from_borrowed_object(vm: &VirtualMachine, obj: &'a PyObject) -> PyResult<Self> {
         obj.try_value_with(
             |s: &PyStr| match s.as_str() {
                 "big" => Ok(Self::Big),

vm/src/protocol/buffer.rs

@@ -136,8 +136,8 @@ impl PyBuffer {
     }
 }
 
-impl TryFromBorrowedObject for PyBuffer {
-    fn try_from_borrowed_object(vm: &VirtualMachine, obj: &PyObject) -> PyResult<Self> {
+impl<'a> TryFromBorrowedObject<'a> for PyBuffer {
+    fn try_from_borrowed_object(vm: &VirtualMachine, obj: &'a PyObject) -> PyResult<Self> {
         let cls = obj.class();
         let as_buffer = cls.mro_find_map(|cls| cls.slots.as_buffer);
         if let Some(f) = as_buffer {

vm/src/stdlib/time.rs

@@ -435,8 +435,8 @@ mod unix {
     #[pyattr]
     use libc::{CLOCK_PROF, CLOCK_UPTIME};
 
-    impl TryFromBorrowedObject for ClockId {
-        fn try_from_borrowed_object(vm: &VirtualMachine, obj: &PyObject) -> PyResult<Self> {
+    impl<'a> TryFromBorrowedObject<'a> for ClockId {
+        fn try_from_borrowed_object(vm: &VirtualMachine, obj: &'a PyObject) -> PyResult<Self> {
             obj.try_to_value(vm).map(ClockId::from_raw)
         }
     }