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