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     5       xturtleDemo - Help

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     9   This document has two sections:

    10 

    11   (1) How to use the demo viewer

    12   (2) How to add your own demos to the demo repository

    13 

    14 

    15   (1) How to use the demo viewer.

    16 

    17   Select a demoscript from the example menu.

    18   The (syntax coloured) source code appears in the left

    19   source code window. IT CANNOT BE EDITED, but ONLY VIEWED!

    20 

    21   - Press START button to start the demo.

    22   - Stop execution by pressing the STOP button.

    23   - Clear screen by pressing the CLEAR button.

    24   - Restart by pressing the START button again.

    25 

    26   SPECIAL demos are those which run EVENTDRIVEN.

    27   (For example clock.py - or oldTurtleDemo.py which

    28   in the end expects a mouse click.):

    29 

    30       Press START button to start the demo.

    31 

    32       - Until the EVENTLOOP is entered everything works

    33       as in an ordinary demo script.

    34 

    35       - When the EVENTLOOP is entered, you control the

    36       application by using the mouse and/or keys (or it's

    37       controlled by some timer events)

    38       To stop it you can and must press the STOP button.

    39 

    40       While the EVENTLOOP is running, the examples menu is disabled.

    41 

    42       - Only after having pressed the STOP button, you may

    43       restart it or choose another example script.

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    45    * * * * * * * *

    46    In some rare situations there may occur interferences/conflicts

    47    between events concerning the demo script and those concerning the

    48    demo-viewer. (They run in the same process.) Strange behaviour may be

    49    the consequence and in the worst case you must close and restart the

    50    viewer.

    51    * * * * * * * *

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    53 

    54    (2) How to add your own demos to the demo repository

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    56    - scriptname: must begin with tdemo_ ,

    57      so it must have the form tdemo_<your-script-name>.py

    58 

    59    - place: same directory as xturtleDemo.py or some

    60      subdirectory, the name of which must also begin with

    61      tdemo_.....

    62 

    63    - requirements on source code:

    64        code must contain a main() function which will

    65        be executed by the viewer (see provided example scripts)

    66        main() may return a string which will be displayed

    67        in the Label below the source code window (when execution

    68        has finished.) 

    69 

    70        !! For programs, which are EVENT DRIVEN, main must return

    71        !! the string "EVENTLOOP". This informs the viewer, that the

    72        !! script is still running and must be stopped by the user!

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    74         

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