Add rename_all attribute to #[pyclass]

guide/pyclass_parameters.md

@@ -11,6 +11,7 @@
 | `mapping` |  Inform PyO3 that this class is a [`Mapping`][params-mapping], and so leave its implementation of sequence C-API slots empty. |
 | <span style="white-space: pre">`module = "module_name"`</span> |  Python code will see the class as being defined in this module. Defaults to `builtins`. |
 | <span style="white-space: pre">`name = "python_name"`</span> | Sets the name that Python sees this class as. Defaults to the name of the Rust struct. |
+| `rename_all` | Renames all variants of the `enum` so that `MyVariant` becomes `MY_VARIANT`. |
 | `sequence` |  Inform PyO3 that this class is a [`Sequence`][params-sequence], and so leave its C-API mapping length slot empty. |
 | `set_all` | Generates setters for all fields of the pyclass. |
 | `subclass` | Allows other Python classes and `#[pyclass]` to inherit from this class. Enums cannot be subclassed. |

newsfragments/3384.added.md

@@ -0,0 +1 @@
+`#[pyclass]` now accepts `rename_all`: this allows renaming all variants of an enum so that `MyVariant` becomes `MY_VARIANT`.

pyo3-macros-backend/Cargo.toml

@@ -16,6 +16,7 @@ edition = "2021"
 [dependencies]
 quote = { version = "1", default-features = false }
 proc-macro2 = { version = "1", default-features = false }
+heck = "0.4"
 
 [dependencies.syn]
 version = "2"

pyo3-macros-backend/src/attributes.rs

@@ -26,6 +26,7 @@ pub mod kw {
     syn::custom_keyword!(module);
     syn::custom_keyword!(name);
     syn::custom_keyword!(pass_module);
+    syn::custom_keyword!(rename_all);
     syn::custom_keyword!(sequence);
     syn::custom_keyword!(set);
     syn::custom_keyword!(set_all);

pyo3-macros-backend/src/pyclass.rs

@@ -16,7 +16,8 @@ use crate::pymethod::{
 };
 use crate::utils::{self, get_pyo3_crate, PythonDoc};
 use crate::PyFunctionOptions;
-use proc_macro2::{Span, TokenStream};
+use heck::ToShoutySnakeCase;
+use proc_macro2::{Ident, Span, TokenStream};
 use quote::quote;
 use syn::ext::IdentExt;
 use syn::parse::{Parse, ParseStream};
@@ -66,6 +67,7 @@ pub struct PyClassPyO3Options {
     pub mapping: Option<kw::mapping>,
     pub module: Option<ModuleAttribute>,
     pub name: Option<NameAttribute>,
+    pub rename_all: Option<kw::rename_all>,
     pub sequence: Option<kw::sequence>,
     pub set_all: Option<kw::set_all>,
     pub subclass: Option<kw::subclass>,
@@ -86,6 +88,7 @@ enum PyClassPyO3Option {
     Mapping(kw::mapping),
     Module(ModuleAttribute),
     Name(NameAttribute),
+    RenameAll(kw::rename_all),
     Sequence(kw::sequence),
     SetAll(kw::set_all),
     Subclass(kw::subclass),
@@ -115,6 +118,8 @@ impl Parse for PyClassPyO3Option {
             input.parse().map(PyClassPyO3Option::Module)
         } else if lookahead.peek(kw::name) {
             input.parse().map(PyClassPyO3Option::Name)
+        } else if lookahead.peek(attributes::kw::rename_all) {
+            input.parse().map(PyClassPyO3Option::RenameAll)
         } else if lookahead.peek(attributes::kw::sequence) {
             input.parse().map(PyClassPyO3Option::Sequence)
         } else if lookahead.peek(attributes::kw::set_all) {
@@ -173,6 +178,7 @@ impl PyClassPyO3Options {
             PyClassPyO3Option::Mapping(mapping) => set_option!(mapping),
             PyClassPyO3Option::Module(module) => set_option!(module),
             PyClassPyO3Option::Name(name) => set_option!(name),
+            PyClassPyO3Option::RenameAll(rename_all) => set_option!(rename_all),
             PyClassPyO3Option::Sequence(sequence) => set_option!(sequence),
             PyClassPyO3Option::SetAll(set_all) => set_option!(set_all),
             PyClassPyO3Option::Subclass(subclass) => set_option!(subclass),
@@ -203,6 +209,11 @@ pub fn build_py_class(
             "#[pyclass] cannot have lifetime parameters. \
             For an explanation, see https://pyo3.rs/latest/class.html#no-lifetime-parameters"
         );
+    } else if let Some(rename_all) = args.options.rename_all {
+        bail_spanned!(
+            rename_all.span() =>
+            "rename_all should only be applied to enums."
+        );
     }
 
     ensure_spanned!(
@@ -379,12 +390,21 @@ struct PyClassEnumVariant<'a> {
 }
 
 impl<'a> PyClassEnumVariant<'a> {
-    fn python_name(&self) -> Cow<'_, syn::Ident> {
-        self.options
+    fn python_name(&self, args: &PyClassArgs) -> Cow<'_, syn::Ident> {
+        let name = self
+            .options
             .name
             .as_ref()
             .map(|name_attr| Cow::Borrowed(&name_attr.value.0))
-            .unwrap_or_else(|| Cow::Owned(self.ident.unraw()))
+            .unwrap_or_else(|| Cow::Owned(self.ident.unraw()));
+        if args.options.rename_all.is_some() {
+            Cow::Owned(Ident::new(
+                &format!("{}", name).to_shouty_snake_case(),
+                Span::call_site(),
+            ))
+        } else {
+            name
+        }
     }
 }
 
@@ -515,7 +535,7 @@ fn impl_enum(
             let repr = format!(
                 "{}.{}",
                 get_class_python_name(cls, args),
-                variant.python_name(),
+                variant.python_name(args),
             );
             quote! { #cls::#variant_name => #repr, }
         });
@@ -597,7 +617,7 @@ fn impl_enum(
         cls,
         args,
         methods_type,
-        enum_default_methods(cls, variants.iter().map(|v| (v.ident, v.python_name()))),
+        enum_default_methods(cls, variants.iter().map(|v| (v.ident, v.python_name(args)))),
         default_slots,
     )
     .doc(doc)

tests/ui/invalid_pyclass_args.stderr

@@ -1,4 +1,4 @@
-error: expected one of: `crate`, `dict`, `extends`, `freelist`, `frozen`, `get_all`, `mapping`, `module`, `name`, `sequence`, `set_all`, `subclass`, `text_signature`, `unsendable`, `weakref`
+error: expected one of: `crate`, `dict`, `extends`, `freelist`, `frozen`, `get_all`, `mapping`, `module`, `name`, `rename_all`, `sequence`, `set_all`, `subclass`, `text_signature`, `unsendable`, `weakref`
  --> tests/ui/invalid_pyclass_args.rs:3:11
   |
 3 | #[pyclass(extend=pyo3::types::PyDict)]
@@ -34,7 +34,7 @@ error: expected string literal
 18 | #[pyclass(module = my_module)]
    |                    ^^^^^^^^^
 
-error: expected one of: `crate`, `dict`, `extends`, `freelist`, `frozen`, `get_all`, `mapping`, `module`, `name`, `sequence`, `set_all`, `subclass`, `text_signature`, `unsendable`, `weakref`
+error: expected one of: `crate`, `dict`, `extends`, `freelist`, `frozen`, `get_all`, `mapping`, `module`, `name`, `rename_all`, `sequence`, `set_all`, `subclass`, `text_signature`, `unsendable`, `weakref`
   --> tests/ui/invalid_pyclass_args.rs:21:11
    |
 21 | #[pyclass(weakrev)]