Fix some arguments for common functions in objfloat and objstr

vm/src/obj/objfloat.rs

@@ -651,7 +651,14 @@ fn to_float(vm: &VirtualMachine, obj: &PyObjectRef) -> PyResult<f64> {
             }
         }
     } else {
-        return Err(vm.new_type_error(format!("can't convert {} to float", obj.class().name)));
+        let method = vm.get_method_or_type_error(obj.clone(), "__float__", || {
+            format!(
+                "float() argument must be a string or a number, not '{}'",
+                obj.class().name
+            )
+        })?;
+        let result = vm.invoke(&method, vec![])?;
+        PyFloatRef::try_from_object(vm, result)?.to_f64()
     };
     Ok(value)
 }
@@ -712,21 +719,6 @@ pub fn get_value(obj: &PyObjectRef) -> f64 {
     obj.payload::<PyFloat>().unwrap().value
 }
 
-fn make_float(vm: &VirtualMachine, obj: &PyObjectRef) -> PyResult<f64> {
-    if let Some(float) = obj.payload_if_subclass::<PyFloat>(vm) {
-        Ok(float.value)
-    } else {
-        let method = vm.get_method_or_type_error(obj.clone(), "__float__", || {
-            format!(
-                "float() argument must be a string or a number, not '{}'",
-                obj.class().name
-            )
-        })?;
-        let result = vm.invoke(&method, vec![])?;
-        Ok(get_value(&result))
-    }
-}
-
 #[derive(Debug, Copy, Clone, PartialEq)]
 pub struct IntoPyFloat {
     value: f64,
@@ -741,7 +733,7 @@ impl IntoPyFloat {
 impl TryFromObject for IntoPyFloat {
     fn try_from_object(vm: &VirtualMachine, obj: PyObjectRef) -> PyResult<Self> {
         Ok(IntoPyFloat {
-            value: make_float(vm, &obj)?,
+            value: to_float(vm, &obj)?,
         })
     }
 }

vm/src/obj/objstr.rs

@@ -1192,13 +1192,8 @@ impl PyString {
     }
 
     #[pymethod]
-    fn encode(
-        zelf: PyRef<Self>,
-        encoding: OptionalArg<PyStringRef>,
-        errors: OptionalArg<PyStringRef>,
-        vm: &VirtualMachine,
-    ) -> PyResult<PyBytesRef> {
-        encode_string(zelf, encoding.into_option(), errors.into_option(), vm)
+    fn encode(zelf: PyRef<Self>, args: EncodeArgs, vm: &VirtualMachine) -> PyResult<PyBytesRef> {
+        encode_string(zelf, args.encoding, args.errors, vm)
     }
 
     #[pymethod(magic)]
@@ -1220,6 +1215,14 @@ impl PyString {
     }
 }
 
+#[derive(FromArgs)]
+struct EncodeArgs {
+    #[pyarg(positional_or_keyword, default = "None")]
+    encoding: Option<PyStringRef>,
+    #[pyarg(positional_or_keyword, default = "None")]
+    errors: Option<PyStringRef>,
+}
+
 pub(crate) fn encode_string(
     s: PyStringRef,
     encoding: Option<PyStringRef>,