Avoid loading `sys` and `platform` modules into namespace when running PYTHONSTARTUP in integrated terminal

[jonathandung]

The following way is the recommended method to run PYTHONSTARTUP in a console, the type of which inherits from code.InteractiveConsole:

if path := os.getenv('PYTHONSTARTUP'):
 with tokenize.open(path) as file:
 sys.audit('cpython.run_startup', path)
 exec(compile(file.read(), path, 'exec'), console.locals)

but this loads the platform and sys modules into the locals dictionary (readline on non-windows as well), polluting the namespace and making for a strange user experience (e.g. when one prints the contents of globals during debugging or when forgetting to import modules works anyways)

From pythonrc.py:

import platform
import sys

if sys.platform != "win32":
 import readline

original_ps1 = ">>> "
is_wsl = "microsoft-standard-WSL" in platform.release()


class REPLHooks:
 def __init__(self):
 self.global_exit = None
 self.failure_flag = False
 self.original_excepthook = sys.excepthook
 self.original_displayhook = sys.displayhook
 sys.excepthook = self.my_excepthook
 sys.displayhook = self.my_displayhook

 def my_displayhook(self, value):
 if value is None:
 self.failure_flag = False

 self.original_displayhook(value)

 def my_excepthook(self, type_, value, traceback):
 self.global_exit = value
 self.failure_flag = True

 self.original_excepthook(type_, value, traceback)


def get_last_command():
 # Get the last history item
 last_command = ""
 if sys.platform != "win32":
 last_command = readline.get_history_item(readline.get_current_history_length())

 return last_command


class PS1:
 hooks = REPLHooks()
 sys.excepthook = hooks.my_excepthook
 sys.displayhook = hooks.my_displayhook

 # str will get called for every prompt with exit code to show success/failure
 def __str__(self):
 exit_code = int(bool(self.hooks.failure_flag))
 self.hooks.failure_flag = False
 # Guide following official VS Code doc for shell integration sequence:
 result = ""
 # For non-windows allow recent_command history.
 if sys.platform != "win32":
 result = "{soh}{command_executed}{command_line}{command_finished}{prompt_started}{stx}{prompt}{soh}{command_start}{stx}".format(
 soh="\001",
 stx="\002",
 command_executed="\x1b]633;C\x07",
 command_line="\x1b]633;E;" + str(get_last_command()) + "\x07",
 command_finished="\x1b]633;D;" + str(exit_code) + "\x07",
 prompt_started="\x1b]633;A\x07",
 prompt=original_ps1,
 command_start="\x1b]633;B\x07",
 )
 else:
 result = "{command_finished}{prompt_started}{prompt}{command_start}{command_executed}".format(
 command_finished="\x1b]633;D;" + str(exit_code) + "\x07",
 prompt_started="\x1b]633;A\x07",
 prompt=original_ps1,
 command_start="\x1b]633;B\x07",
 command_executed="\x1b]633;C\x07",
 )

 # result = f"{chr(27)}]633;D;{exit_code}{chr(7)}{chr(27)}]633;A{chr(7)}{original_ps1}{chr(27)}]633;B{chr(7)}{chr(27)}]633;C{chr(7)}"

 return result

 def __repr__(self):
 return "<Custom PS1 for VS Code Python Shell Integration>"


if sys.platform != "win32" and (not is_wsl):
 sys.ps1 = PS1()

if sys.platform == "darwin":
 print("Cmd click to launch VS Code Native REPL")
else:
 print("Ctrl click to launch VS Code Native REPL")

I propose to add the following at the end of that file:

del platform, sys
if sys.platform != 'win32': del readline