Deprecated exposing objects with buffer interface

This may become unavailable for some Python versions when SWIG is next
updated. See swig/swig#3211

The buffer interface is a lot of overhead for little gain, and using the
data() method to get an object's contents is a lot more explicit.

Author: jim-easterbrook

CHANGELOG.txt

@@ -26,6 +26,8 @@ Changes in v0.18.0:
   4/ Add data() method to exiv2.PreviewImage, deprecate pData() method.
   5/ Deprecated many BasicIo methods (read, write, seek, etc.) that should not
      be needed in Python scripts. Let me know if this is a problem.
+  6/ Deprecated 'buffer interface' to BasicIo, DataBuf, and PreviewImage. They
+     all have 'data()' to get their contents.
 
 Changes in v0.17.3:
   1/ Binary wheels incorporate libexiv2 v0.28.5.

src/interface/shared/buffers.i

@@ -164,6 +164,9 @@ RETURN_VIEW_CB(signature, size_func, flags, NULL, doc_method)
           fragment="get_ptr_size"{object_type}) {
 static int getbuffer_%mangle(object_type)(
         PyObject* exporter, Py_buffer* view, int flags) {
+    // Deprecated since 2025-07-09
+    PyErr_WarnEx(PyExc_DeprecationWarning, "Please use 'data()' to get a"
+                 " memoryview of object_type", 1);
     object_type* self = 0;
     Exiv2::byte* ptr = 0;
     Py_ssize_t size = 0;

src/swig-0_27_7/basicio_wrap.cxx

@@ -4387,6 +4387,9 @@ static bool get_ptr_size(Exiv2::BasicIo* self, bool is_writeable,
 
 static int getbuffer_Exiv2_BasicIo(
         PyObject* exporter, Py_buffer* view, int flags) {
+    // Deprecated since 2025-07-09
+    PyErr_WarnEx(PyExc_DeprecationWarning, "Please use 'data()' to get a"
+                 " memoryview of Exiv2::BasicIo", 1);
     Exiv2::BasicIo* self = 0;
     Exiv2::byte* ptr = 0;
     Py_ssize_t size = 0;

src/swig-0_27_7/preview_wrap.cxx

@@ -5430,6 +5430,9 @@ static bool get_ptr_size(Exiv2::PreviewImage* self, bool is_writeable,
 
 static int getbuffer_Exiv2_PreviewImage(
         PyObject* exporter, Py_buffer* view, int flags) {
+    // Deprecated since 2025-07-09
+    PyErr_WarnEx(PyExc_DeprecationWarning, "Please use 'data()' to get a"
+                 " memoryview of Exiv2::PreviewImage", 1);
     Exiv2::PreviewImage* self = 0;
     Exiv2::byte* ptr = 0;
     Py_ssize_t size = 0;

src/swig-0_27_7/types_wrap.cxx

@@ -4599,6 +4599,9 @@ static bool get_ptr_size(Exiv2::DataBuf* self, bool is_writeable,
 
 static int getbuffer_Exiv2_DataBuf(
         PyObject* exporter, Py_buffer* view, int flags) {
+    // Deprecated since 2025-07-09
+    PyErr_WarnEx(PyExc_DeprecationWarning, "Please use 'data()' to get a"
+                 " memoryview of Exiv2::DataBuf", 1);
     Exiv2::DataBuf* self = 0;
     Exiv2::byte* ptr = 0;
     Py_ssize_t size = 0;

src/swig-0_28_5/basicio_wrap.cxx

@@ -4388,6 +4388,9 @@ static bool get_ptr_size(Exiv2::BasicIo* self, bool is_writeable,
 
 static int getbuffer_Exiv2_BasicIo(
         PyObject* exporter, Py_buffer* view, int flags) {
+    // Deprecated since 2025-07-09
+    PyErr_WarnEx(PyExc_DeprecationWarning, "Please use 'data()' to get a"
+                 " memoryview of Exiv2::BasicIo", 1);
     Exiv2::BasicIo* self = 0;
     Exiv2::byte* ptr = 0;
     Py_ssize_t size = 0;

src/swig-0_28_5/preview_wrap.cxx

@@ -5430,6 +5430,9 @@ static bool get_ptr_size(Exiv2::PreviewImage* self, bool is_writeable,
 
 static int getbuffer_Exiv2_PreviewImage(
         PyObject* exporter, Py_buffer* view, int flags) {
+    // Deprecated since 2025-07-09
+    PyErr_WarnEx(PyExc_DeprecationWarning, "Please use 'data()' to get a"
+                 " memoryview of Exiv2::PreviewImage", 1);
     Exiv2::PreviewImage* self = 0;
     Exiv2::byte* ptr = 0;
     Py_ssize_t size = 0;

src/swig-0_28_5/types_wrap.cxx

@@ -4599,6 +4599,9 @@ static bool get_ptr_size(Exiv2::DataBuf* self, bool is_writeable,
 
 static int getbuffer_Exiv2_DataBuf(
         PyObject* exporter, Py_buffer* view, int flags) {
+    // Deprecated since 2025-07-09
+    PyErr_WarnEx(PyExc_DeprecationWarning, "Please use 'data()' to get a"
+                 " memoryview of Exiv2::DataBuf", 1);
     Exiv2::DataBuf* self = 0;
     Exiv2::byte* ptr = 0;
     Py_ssize_t size = 0;

tests/test_basicio.py

@@ -95,12 +95,13 @@ def test_MemIo(self):
             self.assertEqual(view[0], 0)
         self.assertEqual(io.munmap(), 0)
         # Python buffer interface
-        with memoryview(io) as view:
-            self.assertIsInstance(view, memoryview)
-            self.assertEqual(view, b'')
-            self.assertEqual(view.readonly, False)
-            with self.assertRaises(IndexError):
-                view[0] = 0
+        with self.assertWarns(DeprecationWarning):
+            with memoryview(io) as view:
+                self.assertIsInstance(view, memoryview)
+                self.assertEqual(view, b'')
+                self.assertEqual(view.readonly, False)
+                with self.assertRaises(IndexError):
+                    view[0] = 0
         # data() easy access
         with io.data(False) as view:
             self.assertIsInstance(view, memoryview)
@@ -143,9 +144,10 @@ def test_MemIo(self):
         with self.assertRaises(ValueError):
             self.assertEqual(view1[0], self.data[0])
         # Python buffer interface
-        with memoryview(io) as view:
-            self.assertEqual(view, self.data)
-            self.assertEqual(view.readonly, False)
+        with self.assertWarns(DeprecationWarning):
+            with memoryview(io) as view:
+                self.assertEqual(view, self.data)
+                self.assertEqual(view.readonly, False)
         # data() easy access
         with io.data() as view:
             self.assertIsInstance(view, memoryview)
@@ -214,7 +216,8 @@ def test_MemIo(self):
         with self.assertWarns(DeprecationWarning):
             self.assertEqual(io.write(b'+jim'), 4)
         self.assertEqual(len(io), len(self.data) + 9)
-        self.assertEqual(memoryview(io), self.data + b'+fred+jim')
+        with self.assertWarns(DeprecationWarning):
+            self.assertEqual(memoryview(io), self.data + b'+fred+jim')
 
     def test_ref_counts(self):
         # MemIo keeps a reference to the data buffer

tests/test_exif.py

@@ -199,12 +199,14 @@ def test_ExifThumb(self):
         self.assertEqual(len(thumb.copy()), 0)
         exif_data = exiv2.ExifData()
         thumb = exiv2.ExifThumb(exif_data)
-        thumb.setJpegThumbnail(data)
+        with self.assertWarns(DeprecationWarning):
+            thumb.setJpegThumbnail(data)
         self.assertEqual(len(thumb.copy()), 2532)
         thumb.erase()
         self.assertEqual(len(thumb.copy()), 0)
-        thumb.setJpegThumbnail(
-            data, exiv2.URational((160, 1)), exiv2.URational((120, 1)), 1)
+        with self.assertWarns(DeprecationWarning):
+            thumb.setJpegThumbnail(
+                data, exiv2.URational((160, 1)), exiv2.URational((120, 1)), 1)
         self.assertEqual(len(thumb.copy()), 2532)
         if not exiv2.versionInfo()['EXV_ENABLE_FILESYSTEM']:
             self.skipTest('EXV_ENABLE_FILESYSTEM is off')