Add support for __format__.

Author: ionelmc

Diff for: src/lazy_object_proxy/cext.c

@@ -1182,6 +1182,22 @@ static PyObject *Proxy_aexit(
 
 /* ------------------------------------------------------------------------- */
 
+static PyObject *Proxy_format(
+        ProxyObject *self, PyObject *args, PyObject *kwds)
+{
+    PyObject *format_spec = NULL;
+
+    Proxy__ENSURE_WRAPPED_OR_RETURN_NULL(self);
+
+    if (!PyArg_ParseTuple(args, "|O:format", &format_spec))
+        return NULL;
+
+    return PyObject_Format(self->wrapped, format_spec);
+
+}
+
+/* ------------------------------------------------------------------------- */
+
 static PyObject *Proxy_await(ProxyObject *self)
 {
     Proxy__ENSURE_WRAPPED_OR_RETURN_NULL(self);
@@ -1311,6 +1327,7 @@ static PyMethodDef Proxy_methods[] = {
     { "__round__",     (PyCFunction)Proxy_round,    METH_NOARGS, 0 },
     { "__aenter__",    (PyCFunction)Proxy_aenter,   METH_NOARGS, 0 },
     { "__aexit__",     (PyCFunction)Proxy_aexit,    METH_VARARGS | METH_KEYWORDS, 0 },
+    { "__format__",    (PyCFunction)Proxy_format,   METH_VARARGS, 0 },
     { NULL, NULL },
 };
 

Diff for: src/lazy_object_proxy/simple.py

@@ -91,9 +91,7 @@ def __wrapped__(self):
 
     def __repr__(self, __getattr__=object.__getattribute__):
         if '__wrapped__' in self.__dict__:
-            return '<{} at 0x{:x} wrapping {!r} at 0x{:x} with factory {!r}>'.format(
-                type(self).__name__, id(self), self.__wrapped__, id(self.__wrapped__), self.__factory__
-            )
+            return f'<{type(self).__name__} at 0x{id(self):x} wrapping {self.__wrapped__!r} at 0x{id(self.__wrapped__):x} with factory {self.__factory__!r}>'
         else:
             return f'<{type(self).__name__} at 0x{id(self):x} with factory {self.__factory__!r}>'
 
@@ -249,6 +247,9 @@ def __reduce__(self):
     def __reduce_ex__(self, protocol):
         return identity, (self.__wrapped__,)
 
+    def __format__(self, format_spec):
+        return self.__wrapped__.__format__(format_spec)
+
     if await_:
         from .utils import __aenter__
         from .utils import __aexit__

Diff for: src/lazy_object_proxy/slots.py

@@ -429,6 +429,9 @@ def __reduce__(self):
     def __reduce_ex__(self, protocol):
         return identity, (self.__wrapped__,)
 
+    def __format__(self, format_spec):
+        return self.__wrapped__.__format__(format_spec)
+
     if await_:
         from .utils import __aenter__
         from .utils import __aexit__

Diff for: tests/test_lazy_object_proxy.py

@@ -1955,3 +1955,12 @@ def test_resolved_str(lop):
     assert obj.__resolved__ is False
     str(obj)
     assert obj.__resolved__ is True
+
+
+def test_format(lop):
+    class WithFormat:
+        def __format__(self, format_spec):
+            return f'spec({format_spec!r})'
+
+    obj = lop.Proxy(WithFormat)
+    assert f'{obj:stuff}' == "spec('stuff')"