Apply suggestions from davidhewitt's review

Co-Authored-By: David Hewitt <1939362+davidhewitt@users.noreply.github.com>

guide/src/class.md

@@ -116,7 +116,7 @@ from Rust code (e.g., for testing it).
 `PyCell<T: PyClass>` is always allocated in the Python heap, so we don't have the ownership of it.
 We can get `&PyCell<T>`, not `PyCell<T>`.
 
-Thus, to mutate data behind `&PyCell` safely, we employs
+Thus, to mutate data behind `&PyCell` safely, we employ the
 [Interior Mutability Pattern](https://doc.rust-lang.org/book/ch15-05-interior-mutability.html)
 like [std::cell::RefCell](https://doc.rust-lang.org/std/cell/struct.RefCell.html).
 
@@ -145,13 +145,13 @@ let obj = PyCell::new(py, MyClass { num: 3, debug: true }).unwrap();
 {
     let obj_ref = obj.borrow(); // Get PyRef
     assert_eq!(obj_ref.num, 3);
-    // You cannot get PyRefMut unless all PyRef drop
+    // You cannot get PyRefMut unless all PyRefs are dropped
     assert!(obj.try_borrow_mut().is_err());
 }
 {
     let mut obj_mut = obj.borrow_mut(); // Get PyRefMut
     obj_mut.num = 5;
-    // You cannot get PyRef unless all PyRefMut drop
+    // You cannot get any other refs until the PyRefMut is dropped
     assert!(obj.try_borrow().is_err());
 }
 // You can convert `&PyCell` to Python object

pyo3-derive-backend/src/module.rs

@@ -28,7 +28,7 @@ pub fn py_init(fnname: &Ident, name: &Ident, doc: syn::LitStr) -> TokenStream {
 }
 
 /// Finds and takes care of the #[pyfn(...)] in `#[pymodule]`
-pub fn process_functions_in_module(func: &mut syn::ItemFn) {
+pub fn process_functions_in_module(func: &mut syn::ItemFn) -> syn::Result<()> {
     let mut stmts: Vec<syn::Stmt> = Vec::new();
 
     for stmt in func.block.stmts.iter_mut() {
@@ -36,7 +36,7 @@ pub fn process_functions_in_module(func: &mut syn::ItemFn) {
             if let Some((module_name, python_name, pyfn_attrs)) =
                 extract_pyfn_attrs(&mut func.attrs)
             {
-                let function_to_python = add_fn_to_module(func, python_name, pyfn_attrs);
+                let function_to_python = add_fn_to_module(func, python_name, pyfn_attrs)?;
                 let function_wrapper_ident = function_wrapper_ident(&func.sig.ident);
                 let item: syn::ItemFn = syn::parse_quote! {
                     fn block_wrapper() {
@@ -51,18 +51,19 @@ pub fn process_functions_in_module(func: &mut syn::ItemFn) {
     }
 
     func.block.stmts = stmts;
+    Ok(())
 }
 
 /// Transforms a rust fn arg parsed with syn into a method::FnArg
-fn wrap_fn_argument<'a>(cap: &'a syn::PatType, name: &'a Ident) -> method::FnArg<'a> {
+fn wrap_fn_argument<'a>(cap: &'a syn::PatType, name: &'a Ident) -> syn::Result<method::FnArg<'a>> {
     let (mutability, by_ref, ident) = match *cap.pat {
         syn::Pat::Ident(ref patid) => (&patid.mutability, &patid.by_ref, &patid.ident),
-        _ => panic!("unsupported argument: {:?}", cap.pat),
+        _ => return Err(syn::Error::new_spanned(&cap.pat, "Unsupported argument")),
     };
 
     let py = crate::utils::if_type_is_python(&cap.ty);
     let opt = method::check_arg_ty_and_optional(&name, &cap.ty);
-    method::FnArg {
+    Ok(method::FnArg {
         name: ident,
         mutability,
         by_ref,
@@ -70,7 +71,7 @@ fn wrap_fn_argument<'a>(cap: &'a syn::PatType, name: &'a Ident) -> method::FnArg
         optional: opt,
         py,
         reference: method::is_ref(&name, &cap.ty),
-    }
+    })
 }
 
 /// Extracts the data from the #[pyfn(...)] attribute of a function
@@ -131,7 +132,7 @@ pub fn add_fn_to_module(
     func: &mut syn::ItemFn,
     python_name: Ident,
     pyfn_attrs: Vec<pyfunction::Argument>,
-) -> TokenStream {
+) -> syn::Result<TokenStream> {
     let mut arguments = Vec::new();
     let mut self_ = None;
 
@@ -141,21 +142,15 @@ pub fn add_fn_to_module(
                 self_ = Some(recv.mutability.is_some());
             }
             syn::FnArg::Typed(ref cap) => {
-                arguments.push(wrap_fn_argument(cap, &func.sig.ident));
+                arguments.push(wrap_fn_argument(cap, &func.sig.ident)?);
             }
         }
     }
 
     let ty = method::get_return_info(&func.sig.output);
 
-    let text_signature = match utils::parse_text_signature_attrs(&mut func.attrs, &python_name) {
+    let text_signature = utils::parse_text_signature_attrs(&mut func.attrs, &python_name)?;
-        Ok(text_signature) => text_signature,
+    let doc = utils::get_doc(&func.attrs, text_signature, true)?;
-        Err(err) => return err.to_compile_error(),
-    };
-    let doc = match utils::get_doc(&func.attrs, text_signature, true) {
-        Ok(doc) => doc,
-        Err(err) => return err.to_compile_error(),
-    };
 
     let function_wrapper_ident = function_wrapper_ident(&func.sig.ident);
 
@@ -176,7 +171,7 @@ pub fn add_fn_to_module(
 
     let wrapper = function_c_wrapper(&func.sig.ident, &spec);
 
-    let tokens = quote! {
+    Ok(quote! {
         fn #function_wrapper_ident(py: pyo3::Python) -> pyo3::PyObject {
             #wrapper
 
@@ -199,9 +194,7 @@ pub fn add_fn_to_module(
 
             function
         }
-    };
+    })
-
-    tokens
 }
 
 /// Generate static function wrapper (PyCFunction, PyCFunctionWithKeywords)

pyo3-derive-backend/src/pyfunction.rs

@@ -234,7 +234,7 @@ pub fn parse_name_attribute(attrs: &mut Vec<syn::Attribute>) -> syn::Result<Opti
 pub fn build_py_function(ast: &mut syn::ItemFn, args: PyFunctionAttr) -> syn::Result<TokenStream> {
     let python_name =
         parse_name_attribute(&mut ast.attrs)?.unwrap_or_else(|| ast.sig.ident.unraw());
-    Ok(add_fn_to_module(ast, python_name, args.arguments))
+    add_fn_to_module(ast, python_name, args.arguments)
 }
 
 #[cfg(test)]

pyo3cls/src/lib.rs

@@ -23,7 +23,9 @@ pub fn pymodule(attr: TokenStream, input: TokenStream) -> TokenStream {
         parse_macro_input!(attr as syn::Ident)
     };
 
-    process_functions_in_module(&mut ast);
+    if let Err(err) = process_functions_in_module(&mut ast) {
+        return err.to_compile_error().into();
+    }
 
     let doc = match get_doc(&ast.attrs, None, false) {
         Ok(doc) => doc,

src/derive_utils.rs

@@ -219,7 +219,7 @@ impl GetPropertyValue for PyObject {
     }
 }
 
-/// Utitlities for basetype
+/// Utilities for basetype
 pub trait PyBaseTypeUtils {
     type Dict;
     type WeakRef;

src/objectprotocol.rs

@@ -171,10 +171,10 @@ pub trait ObjectProtocol {
     fn get_type_ptr(&self) -> *mut ffi::PyTypeObject;
 
     /// Gets the Python base object for this object.
-    fn get_base<'py>(&'py self) -> &'py <Self as PyTypeInfo>::BaseType
+    fn get_base(&self) -> &<Self as PyTypeInfo>::BaseType
     where
         Self: PyTypeInfo,
-        <Self as PyTypeInfo>::BaseType: FromPyPointer<'py>;
+        <Self as PyTypeInfo>::BaseType: for<'py> FromPyPointer<'py>;
 
     /// Casts the PyObject to a concrete Python object type.
     fn cast_as<'a, D>(&'a self) -> Result<&'a D, PyDowncastError>
@@ -445,10 +445,10 @@ where
         unsafe { (*self.as_ptr()).ob_type }
     }
 
-    fn get_base<'py>(&'py self) -> &'py <Self as PyTypeInfo>::BaseType
+    fn get_base(&self) -> &<Self as PyTypeInfo>::BaseType
     where
         Self: PyTypeInfo,
-        <Self as PyTypeInfo>::BaseType: FromPyPointer<'py>,
+        <Self as PyTypeInfo>::BaseType: for<'py> FromPyPointer<'py>,
     {
         unsafe { self.py().from_borrowed_ptr(self.as_ptr()) }
     }