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annotate examples/oct_demo.cc @ 17524:534247e14b03

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Merge the official development
author LYH <lyh.kernel@gmail.com>
date Fri, 27 Sep 2013 03:01:11 +0800
parents be41c30bcb44
children
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be41c30bcb44 Re-write documentation and all examples of dynamically linked functions.
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1 // oct_demo.cc -- example of a dynamically linked function for Octave.
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2
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3 // To use this file, your version of Octave must support dynamic
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4 // linking. To find out if it does, type the command
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5 //
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6 // octave_config_info ("ENABLE_DYNAMIC_LINKING")
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7 //
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8 // at the Octave prompt. Support for dynamic linking is included if
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9 // this expression returns the string "yes".
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10 //
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11 // To compile this file, type the command
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12 //
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13 // mkoctfile oct_demo.cc
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14 //
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15 // from within Octave or from the shell prompt. This will create a file
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16 // called oct_demo.oct that can be loaded by Octave. To test the
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17 // oct_demo.oct file, start Octave and type the command
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18 //
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19 // oct_demo ("easy as", 1, 2, 3)
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20 //
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21 // at the Octave prompt. Octave should respond by printing
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22 //
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23 // Hello, world!
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24 // easy as
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25 // 1
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26 // 2
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27 // 3
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28 // ans = 3
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29
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30 // Additional samples of real dynamically loaded functions are available in
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31 // the files of the libinterp/dldfcn directory of the Octave distribution.
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32 // See also the chapter External Code Interface in the documentation.
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33
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34 #include <iostream>
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35
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36 #include <octave/oct.h>
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37
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38 // Every user function should include <octave/oct.h> which imports the
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39 // basic set of Octave header files required. In particular this will define
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40 // the DEFUN_DLD macro (defun-dld.h) which is used for every user function
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41 // that is visible to Octave.
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42
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43 // The four arguments to the DEFUN_DLD macro are:
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44 // 1) The function name as seen in Octave.
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45 // 2) The variable to hold any inputs (of type octave_value_list)
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46 // 3) The number of output arguments
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47 // 4) A string to use as help text if 'help <function_name>' is entered.
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48 //
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49 // Note below that the third parameter (nargout) of DEFUN_DLD is not used,
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50 // so it is omitted from the list of arguments in order to avoid a warning
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51 // from gcc about an unused function parameter.
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52
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53 DEFUN_DLD (oct_demo, args, ,
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54 "[...] = oct_demo (...)\n\
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55 \n\
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56 Print a greeting followed by the values of all the arguments passed.\n\
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57 Return all arguments in reverse order.")
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58 {
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59 // The list of values to return. See the declaration in oct-obj.h
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60
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61 octave_value_list retval;
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62
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63 // This stream is normally connected to the pager.
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64
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65 octave_stdout << "Hello, world!\n";
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66
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67 // The inputs to this function are available in args.
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68
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69 int nargin = args.length ();
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70
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71 // The octave_value_list class is a zero-based array of octave_value objects.
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72 // The declaration for the octave_value class is in the file ov.h.
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73 // The print() method will send its output to octave_stdout,
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74 // so it will also end up going through the pager.
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75
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76 for (int i = 0; i < nargin; i++)
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77 {
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78 octave_value tmp = args(i);
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79 tmp.print (octave_stdout);
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80 retval(nargin-i-1) = tmp;
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81 }
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82
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83 return retval;
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84 }