Added proxy support for __format__() dunder method.

docs/changes.rst

@@ -7,6 +7,11 @@ Version 1.17.0
 Note that version 1.17.0 drops support for Python 3.6 and 3.7. Python version
 3.8 or later is required.
 
+**New Features**
+
+* Add `__format__()` method to `ObjectProxy` class to allow formatting of
+  wrapped object.
+
 **Bugs Fixed**
 
 * When a normal function or builtin function which had `wrapt.decorator` or a

src/wrapt/_wrappers.c

@@ -1284,6 +1284,24 @@ static PyObject *WraptObjectProxy_bytes(
 
 /* ------------------------------------------------------------------------- */
 
+static PyObject *WraptObjectProxy_format(
+        WraptObjectProxyObject *self, PyObject *args)
+{
+    PyObject *format_spec = NULL;
+
+    if (!self->wrapped) {
+      PyErr_SetString(PyExc_ValueError, "wrapper has not been initialized");
+      return NULL;
+    }
+
+    if (!PyArg_ParseTuple(args, "|O:format", &format_spec))
+        return NULL;
+
+    return PyObject_Format(self->wrapped, format_spec);
+}
+
+/* ------------------------------------------------------------------------- */
+
 static PyObject *WraptObjectProxy_reversed(
         WraptObjectProxyObject *self, PyObject *args)
 {
@@ -1797,6 +1815,7 @@ static PyMethodDef WraptObjectProxy_methods[] = {
     { "__getattr__", (PyCFunction)WraptObjectProxy_getattr,
                     METH_VARARGS , 0 },
     { "__bytes__",  (PyCFunction)WraptObjectProxy_bytes, METH_NOARGS, 0 },
+    { "__format__",  (PyCFunction)WraptObjectProxy_format, METH_VARARGS, 0 },
     { "__reversed__", (PyCFunction)WraptObjectProxy_reversed, METH_NOARGS, 0 },
 #if PY_MAJOR_VERSION >= 3
     { "__round__",  (PyCFunction)WraptObjectProxy_round, METH_NOARGS, 0 },

src/wrapt/wrappers.py

@@ -126,6 +126,9 @@ def __repr__(self):
                 type(self.__wrapped__).__name__,
                 id(self.__wrapped__))
 
+    def __format__(self, format_spec):
+        return format(self.__wrapped__, format_spec)
+
     def __reversed__(self):
         return reversed(self.__wrapped__)
 

tests/test_object_proxy.py

@@ -1583,6 +1583,13 @@ def test_repr(self):
 
         self.assertNotEqual(repr(value).find('ObjectProxy at'), -1)
 
+    def test_format(self):
+        value = 1
+
+        proxy = wrapt.ObjectProxy(1)
+
+        self.assertEqual("{:0>3}".format(proxy), "{:0>3}".format(value))
+
 class TestDerivedClassCreation(unittest.TestCase):
 
     def test_derived_new(self):