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83 lines
2.9 KiB
Text
83 lines
2.9 KiB
Text
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----------------------------------------------
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turtleDemo - Help
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----------------------------------------------
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This document has two sections:
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(1) How to use the demo viewer
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(2) How to add your own demos to the demo repository
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(1) How to use the demo viewer.
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Select a demoscript from the example menu.
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The (syntax coloured) source code appears in the left
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source code window. IT CANNOT BE EDITED, but ONLY VIEWED!
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- Press START button to start the demo.
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- Stop execution by pressing the STOP button.
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- Clear screen by pressing the CLEAR button.
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- Restart by pressing the START button again.
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SPECIAL demos are those which run EVENTDRIVEN.
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(For example clock.py - or oldTurtleDemo.py which
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in the end expects a mouse click.):
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Press START button to start the demo.
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- Until the EVENTLOOP is entered everything works
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as in an ordinary demo script.
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- When the EVENTLOOP is entered, you control the
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application by using the mouse and/or keys (or it's
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controlled by some timer events)
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To stop it you can and must press the STOP button.
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While the EVENTLOOP is running, the examples menu is disabled.
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- Only after having pressed the STOP button, you may
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restart it or choose another example script.
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* * * * * * * *
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In some rare situations there may occur interferences/conflicts
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between events concerning the demo script and those concerning the
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demo-viewer. (They run in the same process.) Strange behaviour may be
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the consequence and in the worst case you must close and restart the
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viewer.
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* * * * * * * *
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(2) How to add your own demos to the demo repository
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- Place the file in the same directory as turtledemo/__main__.py
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IMPORTANT! When imported, the demo should not modify the system
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by calling functions in other modules, such as sys, tkinter, or
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turtle. Global variables should be initialized in main().
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- The code must contain a main() function which will
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be executed by the viewer (see provided example scripts).
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It may return a string which will be displayed in the Label below
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the source code window (when execution has finished.)
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- In order to run mydemo.py by itself, such as during development,
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add the following at the end of the file:
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if __name__ == '__main__':
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main()
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mainloop() # keep window open
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python -m turtledemo.mydemo # will then run it
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- If the demo is EVENT DRIVEN, main must return the string
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"EVENTLOOP". This informs the demo viewer that the script is
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still running and must be stopped by the user!
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If an "EVENTLOOP" demo runs by itself, as with clock, which uses
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ontimer, or minimal_hanoi, which loops by recursion, then the
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code should catch the turtle.Terminator exception that will be
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raised when the user presses the STOP button. (Paint is not such
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a demo; it only acts in response to mouse clicks and movements.)
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