1 | /*
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2 | * Project: MoleCuilder
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3 | * Description: creates and alters molecular systems
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4 | * Copyright (C) 2010 University of Bonn. All rights reserved.
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5 | * Please see the LICENSE file or "Copyright notice" in builder.cpp for details.
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6 | */
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7 |
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8 | /**
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9 | * \file actions.dox
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10 | *
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11 | * Created on: Oct 28, 2011
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12 | * Author: heber
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13 | */
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14 |
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15 | /** \page actions Actions
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16 | *
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17 | * \link MoleCuilder::Action Actions \endlink are Command patterns
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18 | * (http://en.wikipedia.org/wiki/Command_pattern)
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19 | * to allow for undoing and redoing. Each specific Action derives from this
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20 | * class to implement a certain functionality. There is a lot of preprocessor
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21 | * magic implemented for making this as easy as possible. In effect you only
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22 | * have to create three files of which only one actually contains more than a
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23 | * few lines, namely the code of the Action itself.
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24 | *
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25 | * Each Action has thus three types of functionalty: do, undo, and redo.
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26 | *
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27 | * The ActionRegistry contains a prototype of each Action under its token
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28 | * such that an instance can be retrieved by knowing this token.
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29 | *
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30 | * Each Action obtains its options from a central ValueStorage such that
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31 | * they are independent of where the option originated from: a command line
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32 | * parameter, a value entered in a graphical dialog or given via the keyboard
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33 | * in a terminal. That's why each begins with a function call to
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34 | * getParametersfromValueStorage() to fill its internal Action::params
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35 | * structure.
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36 | *
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37 | * Also there is a regression test (\ref regression-test) for each Action to
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38 | * check that it always behaves the same no matter how much the code
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39 | * implementing actually has changed.
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40 | *
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41 | * \section actions-add To add a new action ...
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42 | *
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43 | * The following steps have to be done for adding a new action:
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44 | * -# Create three new files .cpp, .def, and .hpp
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45 | * -# Add the files to \b src/Actions/Makefile.am.
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46 | * -# Add the name of the Action to \b src/Actions/GlobalListOfActions.hpp
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47 | * such that the ActionRegistry knows about it and can instantiate a
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48 | * prototype.
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49 | *
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50 | * \section actions-undo-redo Undoing and Redoing actions ...
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51 | *
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52 | * The central points of Actions is that they can be undone and redone. This
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53 | * has to be implemented in two more functions beside the "do".
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54 | *
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55 | * Note that undoing means to get everything back to its original state and by
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56 | * whatever means seem appropriate, e.g. just remvoing all inserted atoms.
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57 | * To make this more elaborate it is usually very useful to store extra information
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58 | * in the Action's state such that undo and redo can be accomplished more quickly.
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59 | * E.g. if your Action creates some new atoms, store their info as \ref AtomicInfo.
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60 | * Then, undo can simply delete the newly created atoms and redo can quickly re-
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61 | * create them in the state they have been before.
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62 | *
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63 | * Have a look at \ref UndoRedoHelpers.hpp for some helper functions on this.
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64 | *
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65 | * \section actions-further Further information
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66 | *
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67 | * If you want know:
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68 | * -# how the code knows about the valid tokens for actions and options and how
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69 | * they are constructed, see \ref MoleCuilder::Action .
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70 | *
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71 | *
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72 | * \date 2012-12-04
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73 | *
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74 | */
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