bpo-26806: IDLE should run without docstrings

Lib/idlelib/idle_test/test_run.py

@@ -292,6 +292,14 @@ def test_default_recursion_limit_preserved(self):
         new_reclimit = sys.getrecursionlimit()
         self.assertEqual(new_reclimit, orig_reclimit)
 
+    def test_fixdoc(self):
+        def func(): "docstring"
+        run.fixdoc(func, "more")
+        self.assertEqual(func.__doc__, "docstring\n\nmore")
+        func.__doc__ = None
+        run.fixdoc(func, "more")
+        self.assertEqual(func.__doc__, "more")
+
 
 if __name__ == '__main__':
     unittest.main(verbosity=2)

Lib/idlelib/run.py

@@ -307,7 +307,12 @@ def fix_scaling(root):
                 font['size'] = round(-0.75*size)
 
 
+def fixdoc(fun, text):
+    tem = (fun.__doc__ + '\n\n') if fun.__doc__ is not None else ''
+    fun.__doc__ = tem + textwrap.fill(textwrap.dedent(text))
+
 RECURSIONLIMIT_DELTA = 30
+
 def install_recursionlimit_wrappers():
     """Install wrappers to always add 30 to the recursion limit."""
     # see: bpo-26806
@@ -329,19 +334,17 @@ def setrecursionlimit(*args, **kwargs):
 
         return setrecursionlimit.__wrapped__(limit + RECURSIONLIMIT_DELTA)
 
-    setrecursionlimit.__doc__ += "\n\n" + textwrap.fill(textwrap.dedent(f"""\
-        This IDLE wrapper adds {RECURSIONLIMIT_DELTA} to prevent possible
-        uninterruptible loops.
-        """).strip())
+    fixdoc(setrecursionlimit, f"""\
+            This IDLE wrapper adds {RECURSIONLIMIT_DELTA} to prevent possible
+            uninterruptible loops.""")
 
     @functools.wraps(sys.getrecursionlimit)
     def getrecursionlimit():
         return getrecursionlimit.__wrapped__() - RECURSIONLIMIT_DELTA
 
-    getrecursionlimit.__doc__ += "\n\n" + textwrap.fill(textwrap.dedent(f"""\
-        This IDLE wrapper subtracts {RECURSIONLIMIT_DELTA} to compensate for
-        the {RECURSIONLIMIT_DELTA} IDLE adds when setting the limit.
-        """).strip())
+    fixdoc(getrecursionlimit, f"""\
+            This IDLE wrapper subtracts {RECURSIONLIMIT_DELTA} to compensate
+            for the {RECURSIONLIMIT_DELTA} IDLE adds when setting the limit.""")
 
     # add the delta to the default recursion limit, to compensate
     sys.setrecursionlimit(sys.getrecursionlimit() + RECURSIONLIMIT_DELTA)