python: Make use of the new structure.is_writable method

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/9027>

subprojects/gst-python/gi/overrides/Gst.py

@@ -423,31 +423,25 @@ class Structure(Gst.Structure):
                 raise TypeError("wrong arguments when creating GstStructure, first argument"
                                 " must be the structure name.")
             struct = Structure.new_empty()
-            struct._writable = True
             return struct
         elif len(args) > 1:
             raise TypeError("wrong arguments when creating GstStructure object")
         elif isinstance(args[0], str):
             if not kwargs:
                 struct = Structure.from_string(args[0])[0]
-                struct._writable = True
                 return struct
             struct = Structure.new_empty(args[0])
-            struct._writable = True
             for k, v in kwargs.items():
                 struct[k] = v
 
-            struct._writable = True
             return struct
         elif isinstance(args[0], Structure):
             struct = args[0].copy()
-            struct._writable = True
             return struct
 
         raise TypeError("wrong arguments when creating GstStructure object")
 
     def __init__(self, *args, **kwargs):
-        self._writable = False
         pass
 
     def __ptr__(self):
@@ -470,8 +464,8 @@ class Structure(Gst.Structure):
         return self.set_value(key, value)
 
     def set_value(self, key, value):
-        if not self._writable:
+        if not _gi_gst.structure_is_writable(self):
-            raise NotWritableStructure("Trying to write to a not writable."
+            raise NotWritableStructure("Trying to write to a not writable structure."
                                        " Make sure to use the right APIs to have access to structure"
                                        " in a writable way.")
 
@@ -855,7 +849,6 @@ def pairwise(iterable):
 
 class StructureWrapper:
     def __init__(self, structure, parent, writable):
-        structure._writable = writable
         self.__structure = structure
         self.__parent__ = parent
 
@@ -863,7 +856,6 @@ class StructureWrapper:
         return self.__structure
 
     def __exit__(self, _type, _value, _tb):
-        self.__structure._writable = False
         self.__parent__ = False
         return
 

subprojects/gst-python/gi/overrides/gstmodule.c

@@ -1026,6 +1026,30 @@ _gst_mini_object_set_flags (PyObject * self, PyObject * args)
   Py_RETURN_NONE;
 }
 
+static PyObject *
+_gst_structure_is_writable (PyObject * self, PyObject * args)
+{
+  PyObject *py_structure, *res;
+  GstStructure *structure;
+
+  py_structure = PyTuple_GetItem (args, 0);
+  if (py_structure == NULL) {
+    PyErr_SetString (PyExc_TypeError, "Expected a PyObject");
+    return NULL;
+  }
+
+  structure = GST_STRUCTURE (pygobject_get (py_structure));
+  if (gst_structure_is_writable (structure)) {
+    Py_INCREF (Py_True);
+    res = Py_True;
+  } else {
+    Py_INCREF (Py_False);
+    res = Py_False;
+  }
+
+  return res;
+}
+
 static PyObject *
 _gst_mini_object_is_writable (PyObject * self, PyObject * args)
 {
@@ -1650,9 +1674,12 @@ static PyMethodDef _gi_gst_functions[] = {
   {"memory_override_map", (PyCFunction) _gst_memory_override_map, METH_VARARGS, NULL},
   {"memory_override_unmap", (PyCFunction) _gst_memory_override_unmap, METH_VARARGS, NULL},
 
+  {"structure_is_writable", (PyCFunction) _gst_structure_is_writable, METH_VARARGS, NULL},
+
   {"caps_get_structure", (PyCFunction) _gst_caps_get_structure, METH_VARARGS, NULL},
   {"caps_writable_structure", (PyCFunction) _gst_caps_writable_structure, METH_VARARGS, NULL},
 
+
   {"mini_object_make_writable", (PyCFunction) _gst_mini_object_make_writable, METH_VARARGS, NULL},
   {"mini_object_is_writable", (PyCFunction) _gst_mini_object_is_writable, METH_VARARGS, NULL},
   {"mini_object_flags", (PyCFunction) _gst_mini_object_flags, METH_VARARGS, NULL},

subprojects/gst-python/testsuite/test_gst.py

@@ -174,6 +174,9 @@ class TestCaps(TestCase):
 
         c2 = caps.mini_object
         self.assertEqual(c2.refcount, 2)
+        with caps.get_structure(0) as s:
+            with self.assertRaises(Gst.NotWritableStructure):
+                s.set_value("rate", 44100)
         caps.make_writable()
 
         with caps.get_structure(0) as s: