gh-122273: Support PyREPL history on Windows (#127141)

Co-authored-by: devdanzin <74280297+devdanzin@users.noreply.github.com>

Lib/_pyrepl/readline.py

@@ -450,7 +450,9 @@ class _ReadlineWrapper:
     def write_history_file(self, filename: str = gethistoryfile()) -> None:
         maxlength = self.saved_history_length
         history = self.get_reader().get_trimmed_history(maxlength)
-        with open(os.path.expanduser(filename), "w", encoding="utf-8") as f:
+        f = open(os.path.expanduser(filename), "w",
+                 encoding="utf-8", newline="\n")
+        with f:
             for entry in history:
                 entry = entry.replace("\n", "\r\n")  # multiline history support
                 f.write(entry + "\n")

Lib/site.py

@@ -498,9 +498,18 @@ def register_readline():
         PYTHON_BASIC_REPL = False
 
     import atexit
+
+    try:
         try:
             import readline
+        except ImportError:
+            readline = None
+        else:
             import rlcompleter  # noqa: F401
+    except ImportError:
+        return
+
+    try:
         if PYTHON_BASIC_REPL:
             CAN_USE_PYREPL = False
         else:
@@ -508,13 +517,19 @@ def register_readline():
             sys.path = [p for p in original_path if p != '']
             try:
                 import _pyrepl.readline
+                if os.name == "nt":
+                    import _pyrepl.windows_console
+                    console_errors = (_pyrepl.windows_console._error,)
+                else:
                     import _pyrepl.unix_console
+                    console_errors = _pyrepl.unix_console._error
                 from _pyrepl.main import CAN_USE_PYREPL
             finally:
                 sys.path = original_path
     except ImportError:
         return
 
+    if readline is not None:
         # Reading the initialization (config) file may not be enough to set a
         # completion key, so we set one first and then read the file.
         if readline.backend == 'editline':
@@ -531,7 +546,7 @@ def register_readline():
             # want to ignore the exception.
             pass
 
-    if readline.get_current_history_length() == 0:
+    if readline is None or readline.get_current_history_length() == 0:
         # If no history was loaded, default to .python_history,
         # or PYTHON_HISTORY.
         # The guard is necessary to avoid doubling history size at
@@ -542,8 +557,10 @@ def register_readline():
 
         if CAN_USE_PYREPL:
             readline_module = _pyrepl.readline
-            exceptions = (OSError, *_pyrepl.unix_console._error)
+            exceptions = (OSError, *console_errors)
         else:
+            if readline is None:
+                return
             readline_module = readline
             exceptions = OSError
 

Misc/NEWS.d/next/Library/2024-11-22-09-23-41.gh-issue-122273.H8M6fd.rst

@@ -0,0 +1 @@
+Support PyREPL history on Windows. Patch by devdanzin and Victor Stinner.