#8198: the Helper class should not save the stdin and stdout objects

at import time, rather by default use the current streams like the
other APIs that output help.

Lib/pydoc.py

@@ -1695,9 +1695,17 @@ class Helper:
         'CONTEXTMANAGERS': ('context-managers', 'with'),
     }
 
-    def __init__(self, input, output):
-        self.input = input
-        self.output = output
+    def __init__(self, input=None, output=None):
+        self._input = input
+        self._output = output
+
+    @property
+    def input(self):
+        return self._input or sys.stdin
+
+    @property
+    def output(self):
+        return self._output or sys.stdout
 
     def __repr__(self):
         if inspect.stack()[1][3] == '?':
@@ -1874,7 +1882,7 @@ Enter any module name to get more help.  Or, type "modules spam" to search
 for modules whose descriptions contain the word "spam".
 ''')
 
-help = Helper(sys.stdin, sys.stdout)
+help = Helper()
 
 class Scanner:
     """A generic tree iterator."""

Misc/NEWS

@@ -15,6 +15,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #8198: In pydoc, output all help text to the correct stream
+  when sys.stdout is reassigned.
+
 - Issue #7909: Do not touch paths with the special prefixes ``\\.\``
   or ``\\?\`` in ntpath.normpath().