Fix bug which made code generation dependend on argument ordering

examples/word-count-cls/src/lib.rs

@@ -5,14 +5,12 @@
 extern crate pyo3;
 extern crate rayon;
 
+use pyo3::prelude::*;
+use pyo3::py::{class, methods, modinit};
+use rayon::prelude::*;
 use std::fs::File;
 use std::io::prelude::*;
 
-use pyo3::prelude::*;
-use rayon::prelude::*;
-
-use pyo3::py::{class, methods, modinit};
-
 #[class(dict)]
 struct WordCounter {
     path: String,

pyo3-derive-backend/src/py_class.rs

@@ -16,8 +16,11 @@ pub fn build_py_class(class: &mut syn::ItemStruct, attr: &Vec<syn::Expr>) -> Tok
     if let syn::Fields::Named(ref mut fields) = class.fields {
         for field in fields.named.iter_mut() {
             if is_python_token(field) {
+                if token.is_none() {
                     token = field.ident.clone();
-                break;
+                } else {
+                    panic!("You can only have one PyToken per class");
+                }
             } else {
                 let field_descs = parse_descriptors(field);
                 if !field_descs.is_empty() {
@@ -48,8 +51,8 @@ fn parse_descriptors(item: &mut syn::Field) -> Vec<FnType> {
                                 "set" => {
                                     descs.push(FnType::Setter(None));
                                 }
-                                _ => {
+                                x => {
-                                    panic!("Only getter and setter supported");
+                                    panic!(r#"Only "get" and "set" supported are, not "{}""#, x);
                                 }
                             }
                         }

tests/test_getter_setter.rs

@@ -52,11 +52,11 @@ fn class_with_properties() {
 
 #[class]
 struct GetterSetter {
+    token: PyToken,
     #[prop(get, set)]
     num: i32,
     #[prop(get, set)]
     text: String,
-    token: PyToken,
 }
 
 #[methods]