new: printto file in main

src/main.rs

@@ -21,7 +21,16 @@ fn main() -> Result<()> {
     let register_map = types::Module::from_xml_dom(doc.root_element())?;
     println!("read: {:#?}", register_map);
 
-    println!("{}", register_map.generate_register_interface()?);
+    // println!("{}", register_map.generate_register_interface()?);
+    fs::write(
+        "testgen.rs",
+        register_map
+            .generate_register_interface(proc_macro2::Ident::new(
+                "a",
+                proc_macro2::Span::call_site(),
+            ))?
+            .to_string(),
+    )?;
 
     Ok(())
 }