Python IDLE 增加清屏功能

（Python2，Python3 通用）

保存如下代码到 ClearWindow.py

"""

Clear Window Extension
Version: 0.2

Author: Roger D. Serwy
        roger.serwy@gmail.com

Date: 2009-06-14

It provides "Clear Shell Window" under "Options"
with ability to undo.

Add these lines to config-extensions.def

[ClearWindow]
enable=1
enable_editor=0
enable_shell=1
[ClearWindow_cfgBindings]
clear-window=<Control-Key-l>

"""

class ClearWindow:

    menudefs = [
        ('options', [None,
               ('Clear Shell Window', '<<clear-window>>'),
       ]),]

    def __init__(self, editwin):
        self.editwin = editwin
        self.text = self.editwin.text
        self.text.bind("<<clear-window>>", self.clear_window2)

        self.text.bind("<<undo>>", self.undo_event)  # add="+" doesn't work

    def undo_event(self, event):
        text = self.text

        text.mark_set("iomark2", "iomark")
        text.mark_set("insert2", "insert")
        self.editwin.undo.undo_event(event)

        # fix iomark and insert
        text.mark_set("iomark", "iomark2")
        text.mark_set("insert", "insert2")
        text.mark_unset("iomark2")
        text.mark_unset("insert2")

    def clear_window2(self, event): # Alternative method
        # work around the ModifiedUndoDelegator
        text = self.text
        text.undo_block_start()
        text.mark_set("iomark2", "iomark")
        text.mark_set("iomark", 1.0)
        text.delete(1.0, "iomark2 linestart")
        text.mark_set("iomark", "iomark2")
        text.mark_unset("iomark2")
        text.undo_block_stop()
        if self.text.compare('insert', '<', 'iomark'):
            self.text.mark_set('insert', 'end-1c')
        self.editwin.set_line_and_column()

    def clear_window(self, event):
        # remove undo delegator
        undo = self.editwin.undo
        self.editwin.per.removefilter(undo)

        # clear the window, but preserve current command
        self.text.delete(1.0, "iomark linestart")
        if self.text.compare('insert', '<', 'iomark'):
            self.text.mark_set('insert', 'end-1c')
        self.editwin.set_line_and_column()

        # restore undo delegator
        self.editwin.per.insertfilter(undo)

将上述文件保存到 C:\Python27\Lib\idlelib 下。再打开此目录下的 config-extensions.def 文件，在其尾部添加如下代码

################################# >>> Added for clear Window
[ClearWindow]
enable=1
enable_editor=0
enable_shell=1
[ClearWindow_cfgBindings]
clear-window=<Control-Key-l>

好了，现在 IDLE 已经可以支持 Ctrl + l 清屏了。

注意：如果遇到 IDLE 快捷键冲突 (我在 Ubuntu 18.04 的 Python3.6.8 IDLE 中遇到过)，例如 IDLE 默认已经定义了 Ctrl + l 为其它用途快捷键，则可以在 IDLE 菜单 Options -> Configure IDLE -> Keys 重新设定快捷键，如下图：

以上方法同样适用于 Linux。在 Linux 下，上述两个文件应该位于： /usr/lib/python2.7/idlelib  或  /usr/lib/python3.4/idlelib  或  /usr/lib64/python2.7/idlelib

完。