Fix Display impl for PyRef

RustPython · OddCoincidence · Mar 21, 2019 · Mar 21, 2019 · Mar 21, 2019 · Mar 21, 2019
commit 0b1b6682c16eee99c44bfd9654aea42445311c80
diff --git a/vm/src/obj/objstr.rs b/vm/src/obj/objstr.rs
@@ -1,3 +1,4 @@
+use std::fmt;
 use std::hash::{Hash, Hasher};
 use std::ops::Range;
 use std::str::FromStr;
@@ -25,11 +26,9 @@ pub struct PyString {
     pub value: String,
 }
 
-impl<T: ToString> From<T> for PyString {
-    fn from(t: T) -> PyString {
-        PyString {
-            value: t.to_string(),
-        }
+impl fmt::Display for PyString {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(&self.value, f)
     }
 }
 

diff --git a/vm/src/obj/objtype.rs b/vm/src/obj/objtype.rs
@@ -1,5 +1,6 @@
 use std::cell::RefCell;
 use std::collections::HashMap;
+use std::fmt;
 
 use crate::function::PyFuncArgs;
 use crate::pyobject::{
@@ -20,6 +21,12 @@ pub struct PyClass {
     pub mro: Vec<PyClassRef>,
 }
 
+impl fmt::Display for PyClass {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(&self.name, f)
+    }
+}
+
 pub type PyClassRef = PyRef<PyClass>;
 
 impl PyValue for PyClass {

diff --git a/vm/src/pyobject.rs b/vm/src/pyobject.rs
@@ -768,9 +768,13 @@ impl<T> IntoPyObject for PyRef<T> {
     }
 }
 
-impl<T> fmt::Display for PyRef<T> {
+impl<T: fmt::Display> fmt::Display for PyRef<T>
+where
+    T: PyValue + fmt::Display,
+{
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.obj.fmt(f)
+        let value: &T = self.obj.payload().expect("unexpected payload for type");
+        fmt::Display::fmt(value, f)
     }
 }