Add aliases of struct member names ending in _

The trailing underscore is not very Pythonic, so the members can also be
accessed without it.

Author: jim-easterbrook

CHANGELOG.txt

@@ -21,6 +21,8 @@ Changes in v0.18.0:
      Value (and derived types) copy constructors
      Single value (such as DateValue) index methods
   2/ Added binary wheels for Linux on arm64.
+  3/ Exiv2 struct member names with a trailing underscore have more Pythonic
+     aliases without the underscore.
 
 Changes in v0.17.3:
   1/ Binary wheels incorporate libexiv2 v0.28.5.

src/interface/shared/struct_dict.i

@@ -26,6 +26,7 @@ static PyObject* list_getset(
     PyObject* result = PyList_New(0);
     PyObject* item = NULL;
     while (getset->name) {
+        // __dict__ is also in the getset list
         if (getset->name[0] != '_') {
             item = (*conv)(obj, getset);
             PyList_Append(result, item);
@@ -35,52 +36,82 @@ static PyObject* list_getset(
     }
     return result;
 };
+static PyGetSetDef* find_getset(PyObject* obj, PyObject* name,
+                                bool strip, bool required) {
+    if (!PyUnicode_Check(name))
+        return NULL;
+    Py_ssize_t size = 0;
+    const char* c_name = PyUnicode_AsUTF8AndSize(name, &size);
+    bool truncate = strip && size > 0 && c_name[size - 1] != '_';
+    PyGetSetDef* getset = Py_TYPE(obj)->tp_getset;
+    size_t len = 0;
+    while (getset->name) {
+        len = strlen(getset->name);
+        if (truncate && getset->name[len - 1] == '_')
+            len--;
+        if (len == (size_t) size && strncmp(getset->name, c_name, len) == 0)
+            return getset;
+        getset++;
+    }
+    if (required)
+        PyErr_Format(PyExc_AttributeError,
+            "'%s' object has no attribute '%U'",
+            Py_TYPE(obj)->tp_name, name);
+    return NULL;
+};
+static int getset_set(PyObject* obj, PyObject* name, PyObject* value,
+                      bool strip, bool required) {
+    PyGetSetDef* getset = find_getset(obj, name, strip, required);
+    if (getset) {
+#if SWIG_VERSION < 0x040400
+        if (!value) {
+            PyErr_Format(PyExc_TypeError,
+                "%s.%s can not be deleted", Py_TYPE(obj)->tp_name, getset->name);
+            return -1;
+        }
+#endif // SWIG_VERSION
+        return getset->set(obj, value, getset->closure);
+    }
+    if (required)
+        return -1;
+    return PyObject_GenericSetAttr(obj, name, value);
+};
 static PyObject* getset_to_value(PyObject* obj, PyGetSetDef* getset) {
     return Py_BuildValue("N", getset->get(obj, getset->closure));
 };
-}
-%fragment("getset_functions_strip", "header",
-          fragment="getset_functions") {
 static PyObject* getset_to_item_strip(PyObject* obj, PyGetSetDef* getset) {
     return Py_BuildValue("(s#N)", getset->name, strlen(getset->name) - 1,
         getset->get(obj, getset->closure));
 };
-static PyObject* getset_to_key_strip(PyObject* obj, PyGetSetDef* getset) {
-    return Py_BuildValue("s#", getset->name, strlen(getset->name) - 1);
-};
-}
-%fragment("getset_functions_nostrip", "header",
-          fragment="getset_functions") {
 static PyObject* getset_to_item_nostrip(PyObject* obj, PyGetSetDef* getset) {
     return Py_BuildValue("(sN)", getset->name,
         getset->get(obj, getset->closure));
 };
+static PyObject* getset_to_key_strip(PyObject* obj, PyGetSetDef* getset) {
+    return Py_BuildValue("s#", getset->name, strlen(getset->name) - 1);
+};
 static PyObject* getset_to_key_nostrip(PyObject* obj, PyGetSetDef* getset) {
     return Py_BuildValue("s", getset->name);
 };
-}
-%fragment("set_attr_no_delete", "header") {
-static int set_attr_no_delete(
-        PyObject* obj, PyObject* name, PyObject* value) {
-    if ((!value) && PyUnicode_Check(name)) {
-        const char* c_name = PyUnicode_AsUTF8(name);
-        PyGetSetDef* getset = Py_TYPE(obj)->tp_getset;
-        while (getset->name) {
-            if (strcmp(getset->name, c_name) == 0) {
-                PyErr_Format(PyExc_TypeError,
-                    "%s.%s can not be deleted",
-                    Py_TYPE(obj)->tp_name, c_name);
-                return -1;
-            }
-            getset++;
-        }
-    }
-    return PyObject_GenericSetAttr(obj, name, value);
+static int set_attr_strip(PyObject* obj, PyObject* name, PyObject* value) {
+   return getset_set(obj, name, value, true, false);
+};
+#if SWIG_VERSION < 0x040400
+static int set_attr_nostrip(PyObject* obj, PyObject* name, PyObject* value) {
+    return getset_set(obj, name, value, false, false);
+};
+#endif // SWIG_VERSION
+static PyObject* get_attr_strip(PyObject* obj, PyObject* name) {
+    PyGetSetDef* getset = find_getset(obj, name, true, false);
+    if (getset)
+        return getset_to_value(obj, getset);
+    return PyObject_GenericGetAttr(obj, name);
 };
 }
 
 // Macro definition
 %define STRUCT_DICT(struct_type, mutable, strip_underscore)
+%fragment("getset_functions");
 // Type slots
 %feature("python:slot", "tp_iter", functype="getiterfunc")
     struct_type::__iter__;
@@ -104,15 +135,13 @@ static int set_attr_no_delete(
 // Add functions
 %extend struct_type {
 #if #strip_underscore == "true"
-    %fragment("getset_functions_strip");
     PyObject* items(PyObject* py_self) {
         return list_getset(py_self, getset_to_item_strip);
     }
     PyObject* keys(PyObject* py_self) {
         return list_getset(py_self, getset_to_key_strip);
     }
 #else
-    %fragment("getset_functions_nostrip");
     PyObject* items(PyObject* py_self) {
         return list_getset(py_self, getset_to_item_nostrip);
     }
@@ -130,33 +159,31 @@ static int set_attr_no_delete(
         Py_DECREF(seq);
         return result;
     }
-    PyObject* __getitem__(PyObject* py_self, const std::string& key) {
-#if #strip_underscore == "true"
-        return PyObject_GetAttrString(py_self, (key + '_').c_str());
-#else
-        return PyObject_GetAttrString(py_self, key.c_str());
-#endif // strip_underscore
+    PyObject* __getitem__(PyObject* py_self, PyObject* key) {
+        PyGetSetDef* getset = find_getset(
+            py_self, key, strip_underscore, true);
+        if (!getset)
+            return NULL;
+        return getset_to_value(py_self, getset);
     }
 }
+#if #strip_underscore == "true"
+%feature("python:tp_getattro") struct_type "get_attr_strip";
+#endif // strip_underscore
 #if #mutable == "true"
-%fragment("set_attr_no_delete");
-%feature("python:tp_setattro") struct_type "set_attr_no_delete";
+#if #strip_underscore == "true"
+%feature("python:tp_setattro") struct_type "set_attr_strip";
+#else // strip_underscore
+#if SWIG_VERSION < 0x040400
+%feature("python:tp_setattro") struct_type "set_attr_nostrip";
+#endif // SWIG_VERSION
+#endif // strip_underscore
 %feature("python:slot", "mp_ass_subscript", functype="objobjargproc")
     struct_type::__setitem__;
 %extend struct_type {
-    PyObject* __setitem__(PyObject* py_self, const std::string& key,
+    PyObject* __setitem__(PyObject* py_self, PyObject* key,
                           PyObject* value) {
-        if (!value)
-            return PyErr_Format(PyExc_TypeError,
-                "%s['%s'] can not be deleted", Py_TYPE(py_self)->tp_name,
-                key.c_str());
-#if #strip_underscore == "true"
-        int error = PyObject_SetAttrString(
-            py_self, (key + '_').c_str(), value);
-#else
-        int error = PyObject_SetAttrString(py_self, key.c_str(), value);
-#endif // strip_underscore
-        if (error)
+        if (getset_set(py_self, key, value, strip_underscore, true))
             return NULL;
         return SWIG_Py_Void();
     }