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1 Summary of changes for version 3.0: |
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2 ---------------------------------- |
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3 |
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4 * Previous versions of Octave had a number of built-in variables to |
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5 control warnings (for example, warn_divide_by_zero). These |
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6 variables have been replaced by warning identifiers that are used |
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7 with the warning function to control the state of warnings. |
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8 |
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9 For example, instead of writing |
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10 |
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11 warn_divide_by_zero = false; |
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12 |
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13 to disable divide-by-zero warnings, you should write |
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14 |
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15 warning ("off", "Octave:divide-by-zero"); |
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16 |
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17 You may use the same technique in your own code to control |
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18 warnings. For example, you can use |
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19 |
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20 warning ("My-package:phase-of-the-moon", |
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21 "the phase of the moon could cause trouble today"); |
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22 |
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23 to allow users to control this warning using the |
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24 "My-package:phase-of-the-moon" warning identifier. |
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25 |
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26 You may also enable or disable all warnings, or turn them into |
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27 errors: |
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28 |
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29 warning ("on", "all"); |
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30 warning ("off", "all"); |
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31 warning ("error", "Octave:divide-by-zero"); |
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32 warning ("error", "all"); |
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33 |
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34 You can query the state of current warnings using |
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35 |
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36 warning ("query", ID) |
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37 warning ("query") |
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38 |
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39 (only those warning IDs which have been explicitly set are |
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40 returned). |
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41 |
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42 A partial list and description of warning identifiers is available |
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43 using |
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44 |
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45 help warning_ids |
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46 |
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47 |
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48 * All built-in variables have been converted to functions. This |
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49 change simplifies the interpreter and allows a consistent |
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50 interface to internal variables for user-defined packages and the |
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51 core functions distributed with Octave. In most cases, code that |
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52 simply accesses internal variables does not need to change. Code |
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53 that sets internal variables will change. For example, instead of |
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54 writing |
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55 |
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56 PS1 = ">> "; |
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57 |
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58 you will need to write |
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59 |
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60 PS1 (">> "); |
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61 |
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62 If you need write code that will run in both old and new versions |
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63 of Octave, you can use something like |
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64 |
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65 if (exist ("OCTAVE_VERSION") == 5) |
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66 ## New: |
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67 PS1 (">> "); |
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68 else |
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69 ## Old: |
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70 PS1 = ">> "; |
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71 endif |
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72 |
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73 |
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74 See NEWS.2 for old news. |
