Add documentation to the dict implementation

Issue #27350.

1 files changed, 9 insertions, 0 deletions

diff --git a/Include/dictobject.h b/Include/dictobject.h
index ba90aaf676..02d40ff386 100644
--- a/Include/dictobject.h
+++ b/Include/dictobject.h
@@ -22,8 +22,17 @@ typedef struct _dictkeysobject PyDictKeysObject;
  */
 typedef struct {
     PyObject_HEAD
+
+    /* Number of items in the dictionary */
     Py_ssize_t ma_used;
+
     PyDictKeysObject *ma_keys;
+
+    /* If ma_values is NULL, the table is "combined": keys and values
+       are stored in ma_keys (and ma_keys->dk_refcnt == 1).
+
+       If ma_values is not NULL, the table is splitted:
+       keys are stored in ma_keys and values are stored in ma_values */
     PyObject **ma_values;
 } PyDictObject;