refactor: switch to declarative module

It may be possible that "imperative" module declarations will get
deprecated, according to [1], so switch to declarative syntax even
though it means more boilerplate due to missing `#[pymodule_export]`
capability on glob `use`s.

[1]: PyO3/pyo3#3900

src/lib.rs

@@ -10,33 +10,61 @@ mod syntax;
 mod values;
 
 #[pymodule]
-fn xingque(m: &Bound<'_, PyModule>) -> PyResult<()> {
-    m.add(
-        "VERSION",
-        option_env!("CARGO_PKG_VERSION").unwrap_or("unknown"),
-    )?;
-    m.add("STARLARK_RUST_VERSION", "0.12.0")?; // TODO: query this from Cargo
-    m.add_class::<codemap::PyCodeMap>()?;
-    m.add_class::<codemap::PyFileSpan>()?;
-    m.add_class::<codemap::PyPos>()?;
-    m.add_class::<codemap::PyResolvedFileLine>()?;
-    m.add_class::<codemap::PyResolvedFileSpan>()?;
-    m.add_class::<codemap::PyResolvedPos>()?;
-    m.add_class::<codemap::PyResolvedSpan>()?;
-    m.add_class::<codemap::PySpan>()?;
-    m.add_class::<environment::PyFrozenModule>()?;
-    m.add_class::<environment::PyGlobals>()?;
-    m.add_class::<environment::PyGlobalsBuilder>()?;
-    m.add_class::<environment::PyLibraryExtension>()?;
-    m.add_class::<environment::PyModule>()?;
-    m.add_class::<eval::PyDictFileLoader>()?;
-    m.add_class::<eval::PyEvaluator>()?;
-    m.add_class::<syntax::PyAstModule>()?;
-    m.add_class::<syntax::PyDialect>()?;
-    m.add_class::<syntax::PyDialectTypes>()?;
-    m.add_class::<values::PyFrozenValue>()?;
-    m.add_class::<values::PyHeap>()?;
-    m.add_class::<values::PyHeapSummary>()?;
-    m.add_class::<values::PyValue>()?;
-    Ok(())
+mod xingque {
+    use super::*;
+
+    #[pymodule_export]
+    use codemap::PyCodeMap;
+    #[pymodule_export]
+    use codemap::PyFileSpan;
+    #[pymodule_export]
+    use codemap::PyPos;
+    #[pymodule_export]
+    use codemap::PyResolvedFileLine;
+    #[pymodule_export]
+    use codemap::PyResolvedFileSpan;
+    #[pymodule_export]
+    use codemap::PyResolvedPos;
+    #[pymodule_export]
+    use codemap::PyResolvedSpan;
+    #[pymodule_export]
+    use codemap::PySpan;
+    #[pymodule_export]
+    use environment::PyFrozenModule;
+    #[pymodule_export]
+    use environment::PyGlobals;
+    #[pymodule_export]
+    use environment::PyGlobalsBuilder;
+    #[pymodule_export]
+    use environment::PyLibraryExtension;
+    #[pymodule_export]
+    use environment::PyModule;
+    #[pymodule_export]
+    use eval::PyDictFileLoader;
+    #[pymodule_export]
+    use eval::PyEvaluator;
+    #[pymodule_export]
+    use syntax::PyAstModule;
+    #[pymodule_export]
+    use syntax::PyDialect;
+    #[pymodule_export]
+    use syntax::PyDialectTypes;
+    #[pymodule_export]
+    use values::PyFrozenValue;
+    #[pymodule_export]
+    use values::PyHeap;
+    #[pymodule_export]
+    use values::PyHeapSummary;
+    #[pymodule_export]
+    use values::PyValue;
+
+    #[pymodule_init]
+    fn init(m: &Bound<'_, pyo3::types::PyModule>) -> PyResult<()> {
+        m.add(
+            "VERSION",
+            option_env!("CARGO_PKG_VERSION").unwrap_or("unknown"),
+        )?;
+        m.add("STARLARK_RUST_VERSION", "0.12.0")?; // TODO: query this from Cargo
+        Ok(())
+    }
 }