Merge pull request #444 from skinny121/object_format

cthulahoops · web-flow · commit 8835b47d1f0d · 2019-02-12T08:52:20.000Z
Add object.__format__
diff --git a/tests/snippets/builtin_format.py b/tests/snippets/builtin_format.py
@@ -6,3 +6,12 @@
     pass
 else:
     assert False, "TypeError not raised when format is called with a number"
+
+assert format({}) == "{}"
+
+try:
+    format({}, 'b')
+except TypeError:
+    pass
+else:
+    assert False, "TypeError not raised when format_spec not empty for dict"
diff --git a/vm/src/builtins.rs b/vm/src/builtins.rs
@@ -281,10 +281,13 @@ fn builtin_format(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
     arg_check!(
         vm,
         args,
-        required = [(obj, None), (format_spec, Some(vm.ctx.str_type()))]
+        required = [(obj, None)],
+        optional = [(format_spec, Some(vm.ctx.str_type()))]
     );
-
-    vm.call_method(obj, "__format__", vec![format_spec.clone()])
+    let format_spec = format_spec
+        .cloned()
+        .unwrap_or_else(|| vm.new_str("".to_string()));
+    vm.call_method(obj, "__format__", vec![format_spec])
 }
 
 fn builtin_getattr(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
diff --git a/vm/src/obj/objobject.rs b/vm/src/obj/objobject.rs
@@ -83,6 +83,22 @@ fn object_repr(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
     Ok(vm.new_str(format!("<{} object at 0x{:x}>", type_name, address)))
 }
 
+fn object_format(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
+    arg_check!(
+        vm,
+        args,
+        required = [
+            (obj, Some(vm.ctx.object())),
+            (format_spec, Some(vm.ctx.str_type()))
+        ]
+    );
+    if objstr::get_value(format_spec).is_empty() {
+        vm.to_str(obj)
+    } else {
+        Err(vm.new_type_error("unsupported format string passed to object.__format__".to_string()))
+    }
+}
+
 pub fn init(context: &PyContext) {
     let object = &context.object;
     let object_doc = "The most base type";
@@ -100,6 +116,7 @@ pub fn init(context: &PyContext) {
     context.set_attr(&object, "__hash__", context.new_rustfunc(object_hash));
     context.set_attr(&object, "__str__", context.new_rustfunc(object_str));
     context.set_attr(&object, "__repr__", context.new_rustfunc(object_repr));
+    context.set_attr(&object, "__format__", context.new_rustfunc(object_format));
     context.set_attr(
         &object,
         "__getattribute__",
