Improve `hash()` builtin docstring with caveats. (GH-125229)

Improve  `hash()` builtin docstring with caveats.

Mention its return type and that the value can be expected to change between
processes (hash randomization).

Why? The `hash` builtin gets reached for and used by a lot of people whether it
is the right tool or not. IDEs surface docstrings and people use pydoc and
`help(hash)`.

diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index fec64e1ff9d25f42689fe6117c4906535d778943..16413d784cc87cdeaf93a21983544155baaff944 100644 (file)
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -1840,15 +1840,17 @@ hash as builtin_hash
     obj: object
     /
 
-Return the hash value for the given object.
+Return the integer hash value for the given object.
 
-Two objects that compare equal must also have the same hash value, but the
-reverse is not necessarily true.
+Two objects that compare equal must also have the same hash value, but
+the reverse is not necessarily true.  Hash values may differ between
+Python processes.  Not all objects are hashable; calling hash() on an
+unhashable object raises TypeError.
 [clinic start generated code]*/
 
 static PyObject *
 builtin_hash(PyObject *module, PyObject *obj)
-/*[clinic end generated code: output=237668e9d7688db7 input=58c48be822bf9c54]*/
+/*[clinic end generated code: output=237668e9d7688db7 input=70a242ff65f6717c]*/
 {
     Py_hash_t x;
 

diff --git a/Python/clinic/bltinmodule.c.h b/Python/clinic/bltinmodule.c.h
index c8c141f863d26aa0745e38b055db6f52f1061c0a..e6b845cd375d73ad1cf8576537d9749cf60a4c42 100644 (file)
--- a/Python/clinic/bltinmodule.c.h
+++ b/Python/clinic/bltinmodule.c.h
@@ -826,10 +826,12 @@ PyDoc_STRVAR(builtin_hash__doc__,
 "hash($module, obj, /)\n"
 "--\n"
 "\n"
-"Return the hash value for the given object.\n"
+"Return the integer hash value for the given object.\n"
 "\n"
-"Two objects that compare equal must also have the same hash value, but the\n"
-"reverse is not necessarily true.");
+"Two objects that compare equal must also have the same hash value, but\n"
+"the reverse is not necessarily true.  Hash values may differ between\n"
+"Python processes.  Not all objects are hashable; calling hash() on an\n"
+"unhashable object raises TypeError.");
 
 #define BUILTIN_HASH_METHODDEF    \
     {"hash", (PyCFunction)builtin_hash, METH_O, builtin_hash__doc__},
@@ -1380,4 +1382,4 @@ builtin_issubclass(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=1c3327da8885bb8e input=a9049054013a1b77]*/
+/*[clinic end generated code: output=f1fc836a63d89826 input=a9049054013a1b77]*/