[pygi] Make the "wrong argument count" exception more explicit.

[Steve Frécinaux <sfre src gnome org>]

commit 07df124dc06cf506634e95d08397f50a2d07fce2
Author: Steve Frécinaux <code istique net>
Date:   Mon Jun 7 09:47:23 2010 +0200

    Make the "wrong argument count" exception more explicit.
    
    Previously we had messages like this one:
    TypeError: takes exactly 2 argument(s) (1 given)
    
    With this patch, they become like this:
    TypeError: get_end_iter() takes exactly 2 argument(s) (1 given)
    
    It makes things much easier to debug when there are several pygi calls
    on the same line.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=620804

 gi/pygi-invoke.c         |    3 ++-
 tests/test_everything.py |    6 ++++++
 2 files changed, 8 insertions(+), 1 deletions(-)
---
diff --git a/gi/pygi-invoke.c b/gi/pygi-invoke.c
index 7ac1685..63e57e7 100644
--- a/gi/pygi-invoke.c
+++ b/gi/pygi-invoke.c
@@ -233,7 +233,8 @@ _prepare_invocation_state (struct invocation_state *state,
 
         if (state->n_py_args != n_py_args_expected) {
             PyErr_Format (PyExc_TypeError,
-                          "takes exactly %zd argument(s) (%zd given)",
+                          "%s() takes exactly %zd argument(s) (%zd given)",
+                          g_base_info_get_name ( (GIBaseInfo *) function_info),
                           n_py_args_expected, state->n_py_args);
             return FALSE;
         }
diff --git a/tests/test_everything.py b/tests/test_everything.py
index 0463d2c..06a8d8c 100644
--- a/tests/test_everything.py
+++ b/tests/test_everything.py
@@ -79,6 +79,12 @@ class TestEverything(unittest.TestCase):
         self.assertEquals(struct_b.nested_a.some_double, struct_b_clone.nested_a.some_double)
         self.assertEquals(struct_b.nested_a.some_enum, struct_b_clone.nested_a.some_enum)
 
+    def test_wrong_type_of_arguments(self):
+        try:
+            Everything.test_int8()
+        except TypeError, e:
+            self.assertEquals(e.args, ("test_int8() takes exactly 1 argument(s) (0 given)",))
+
 class TestNullableArgs(unittest.TestCase):
     def test_in_nullable_hash(self):
         Everything.test_ghash_null_in(None)