Issue #10291: Cleanup turtledemo to use docstrings for help.

(Original patch by Alexander Belopolsky, refreshed by Jessica McKellar.)

Lib/turtledemo/__init__.py

+"""
+    --------------------------------------
+        About this viewer
+    --------------------------------------
+
+    Tiny demo viewer to view turtle graphics example scripts.
+
+    Quickly and dirtyly assembled by Gregor Lingl.
+    June, 2006
+
+    For more information see: turtledemo - Help
+
+    Have fun!
+"""

Lib/turtledemo/__main__.py

 #!/usr/bin/env python3
+
+"""
+  ----------------------------------------------
+
+      turtledemo - Help
+
+  ----------------------------------------------
+
+  This document has two sections:
+
+  (1) How to use the demo viewer
+  (2) How to add your own demos to the demo repository
+
+
+  (1) How to use the demo viewer.
+
+  Select a demoscript from the example menu.
+  The (syntax coloured) source code appears in the left
+  source code window. IT CANNOT BE EDITED, but ONLY VIEWED!
+
+  - Press START button to start the demo.
+  - Stop execution by pressing the STOP button.
+  - Clear screen by pressing the CLEAR button.
+  - Restart by pressing the START button again.
+
+  SPECIAL demos are those which run EVENTDRIVEN.
+  (For example clock.py - or oldTurtleDemo.py which
+  in the end expects a mouse click.):
+
+      Press START button to start the demo.
+
+      - Until the EVENTLOOP is entered everything works
+      as in an ordinary demo script.
+
+      - When the EVENTLOOP is entered, you control the
+      application by using the mouse and/or keys (or it's
+      controlled by some timer events)
+      To stop it you can and must press the STOP button.
+
+      While the EVENTLOOP is running, the examples menu is disabled.
+
+      - Only after having pressed the STOP button, you may
+      restart it or choose another example script.
+
+   * * * * * * * *
+   In some rare situations there may occur interferences/conflicts
+   between events concerning the demo script and those concerning the
+   demo-viewer. (They run in the same process.) Strange behaviour may be
+   the consequence and in the worst case you must close and restart the
+   viewer.
+   * * * * * * * *
+
+
+   (2) How to add your own demos to the demo repository
+
+   - place: same directory as turtledemo/__main__.py
+
+   - requirements on source code:
+       code must contain a main() function which will
+       be executed by the viewer (see provided example scripts)
+       main() may return a string which will be displayed
+       in the Label below the source code window (when execution
+       has finished.)
+
+       !! For programs, which are EVENT DRIVEN, main must return
+       !! the string "EVENTLOOP". This informs the viewer, that the
+       !! script is still running and must be stopped by the user!
+"""
 import sys
 import os
 
 from tkinter import *
 from idlelib.Percolator import Percolator
 from idlelib.ColorDelegator import ColorDelegator
-from idlelib.textView import view_file # TextViewer
+from idlelib.textView import view_text # TextViewer
 from importlib import reload
+from turtledemo import __doc__ as about_turtledemo
 
 import turtle
 import time
@@ -28,16 +97,13 @@ def getExampleEntries():
             entry.endswith(".py") and entry[0] != '_']
 
 def showDemoHelp():
-    view_file(demo.root, "Help on turtleDemo",
-              os.path.join(demo_dir, "demohelp.txt"))
+    view_text(demo.root, "Help on turtledemo", __doc__)
 
 def showAboutDemo():
-    view_file(demo.root, "About turtleDemo",
-              os.path.join(demo_dir, "about_turtledemo.txt"))
+    view_text(demo.root, "About turtledemo", about_turtledemo)
 
 def showAboutTurtle():
-    view_file(demo.root, "About the new turtle module.",
-              os.path.join(demo_dir, "about_turtle.txt"))
+    view_text(demo.root, "About the turtle module.", turtle.__doc__)
 
 class DemoWindow(object):
 

Lib/turtledemo/about_turtle.txt

-
-========================================================
-    A new turtle module for Python
-========================================================
-
-Turtle graphics is a popular way for introducing programming to
-kids. It was part of the original Logo programming language developed
-by Wally Feurzig and Seymour Papert in 1966.
-
-Imagine a robotic turtle starting at (0, 0) in the x-y plane. After an ``import turtle``, give it
-the command turtle.forward(15), and it moves (on-screen!) 15 pixels in
-the direction it is facing, drawing a line as it moves. Give it the
-command turtle.right(25), and it rotates in-place 25 degrees clockwise.
-
-By combining together these and similar commands, intricate shapes and
-pictures can easily be drawn.
-
------ turtle.py
-
-This module is an extended reimplementation of turtle.py from the
-Python standard distribution up to Python 2.5. (See: http:\\www.python.org)
-
-It tries to keep the merits of turtle.py and to be (nearly) 100%
-compatible with it. This means in the first place to enable the
-learning programmer to use all the commands, classes and methods
-interactively when using the module from within IDLE run with
-the -n switch.
-
-Roughly it has the following features added:
-
-- Better animation of the turtle movements, especially of turning the
-    turtle. So the turtles can more easily be used as a visual feedback
-    instrument by the (beginning) programmer.
-
-- Different turtle shapes, gif-images as turtle shapes, user defined
-    and user controllable turtle shapes, among them compound
-    (multicolored) shapes. Turtle shapes can be stgretched and tilted, which
-    makes turtles zu very versatile geometrical objects.
-
-- Fine control over turtle movement and screen updates via delay(),
-    and enhanced tracer() and speed() methods.
-
-- Aliases for the most commonly used commands, like fd for forward etc.,
-    following the early Logo traditions. This reduces the boring work of
-    typing long sequences of commands, which often occur in a natural way
-    when kids try to program fancy pictures on their first encounter with
-    turtle graphcis.
-
-- Turtles now have an undo()-method with configurable undo-buffer.
-
-- Some simple commands/methods for creating event driven programs
-    (mouse-, key-, timer-events). Especially useful for programming games.
-
-- A scrollable Canvas class. The default scrollable Canvas can be
-    extended interactively as needed while playing around with the turtle(s).
-
-- A TurtleScreen class with methods controlling background color or
-    background image, window and canvas size and other properties of the
-    TurtleScreen.
-
-- There is a method, setworldcoordinates(), to install a user defined
-    coordinate-system for the TurtleScreen.
-
-- The implementation uses a 2-vector class named Vec2D, derived from tuple.
-    This class is public, so it can be imported by the application programmer,
-    which makes certain types of computations very natural and compact.
-
-- Appearance of the TurtleScreen and the Turtles at startup/import can be
-    configured by means of a turtle.cfg configuration file.
-    The default configuration mimics the appearance of the old turtle module.
-
-- If configured appropriately the module reads in docstrings from a docstring
-    dictionary in some different language, supplied separately  and replaces
-    the english ones by those read in. There is a utility function
-    write_docstringdict() to write a dictionary with the original (english)
-    docstrings to disc, so it can serve as a template for translations.

Lib/turtledemo/about_turtledemo.txt

-
-    --------------------------------------
-        About this viewer
-    --------------------------------------
-
-    Tiny demo viewer to view turtle graphics example scripts.
-
-    Quickly and dirtyly assembled by Gregor Lingl.
-    June, 2006
-
-    For more information see: turtleDemo - Help
-
-    Have fun!

Lib/turtledemo/demohelp.txt

-
-
-  ----------------------------------------------
-
-      turtleDemo - Help
-
-  ----------------------------------------------
-
-  This document has two sections:
-
-  (1) How to use the demo viewer
-  (2) How to add your own demos to the demo repository
-
-
-  (1) How to use the demo viewer.
-
-  Select a demoscript from the example menu.
-  The (syntax coloured) source code appears in the left
-  source code window. IT CANNOT BE EDITED, but ONLY VIEWED!
-
-  - Press START button to start the demo.
-  - Stop execution by pressing the STOP button.
-  - Clear screen by pressing the CLEAR button.
-  - Restart by pressing the START button again.
-
-  SPECIAL demos are those which run EVENTDRIVEN.
-  (For example clock.py - or oldTurtleDemo.py which
-  in the end expects a mouse click.):
-
-      Press START button to start the demo.
-
-      - Until the EVENTLOOP is entered everything works
-      as in an ordinary demo script.
-
-      - When the EVENTLOOP is entered, you control the
-      application by using the mouse and/or keys (or it's
-      controlled by some timer events)
-      To stop it you can and must press the STOP button.
-
-      While the EVENTLOOP is running, the examples menu is disabled.
-
-      - Only after having pressed the STOP button, you may
-      restart it or choose another example script.
-
-   * * * * * * * *
-   In some rare situations there may occur interferences/conflicts
-   between events concerning the demo script and those concerning the
-   demo-viewer. (They run in the same process.) Strange behaviour may be
-   the consequence and in the worst case you must close and restart the
-   viewer.
-   * * * * * * * *
-
-
-   (2) How to add your own demos to the demo repository
-
-   - place: same directory as turtledemo/__main__.py
-
-   - requirements on source code:
-       code must contain a main() function which will
-       be executed by the viewer (see provided example scripts)
-       main() may return a string which will be displayed
-       in the Label below the source code window (when execution
-       has finished.) 
-
-       !! For programs, which are EVENT DRIVEN, main must return
-       !! the string "EVENTLOOP". This informs the viewer, that the
-       !! script is still running and must be stopped by the user!
-
-        
-