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| 3 | <html> |
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| 4 | <head> |
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| 6 | <link rel="stylesheet" type="text/css" href="../../../../boost.css"> |
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| 7 | <title>Policies</title> |
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| 8 | </head> |
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| 9 | |
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| 10 | <body lang="en"> |
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| 11 | <h1>Policies</h1> |
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| 12 | |
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| 13 | <p>The <code>interval</code> template requires two arguments. The first |
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| 14 | corresponds to the base type chosen for the bounds. And the second defines |
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| 15 | the <a href="rounding.htm">rounding</a> and <a |
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| 16 | href="checking.htm">checking</a> behaviors of the newly constructed class. |
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| 17 | This second argument is not mandatory but may need some customizations. In |
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| 18 | order to ease the manipulations, some helper templates are provided in |
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| 19 | <code>interval/policies.hpp</code>.</p> |
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| 20 | <pre>namespace boost { |
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| 21 | namespace numeric { |
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| 22 | namespace interval_lib { |
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| 23 | |
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| 24 | template<class Rounding, class Checking> |
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| 25 | struct policies { |
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| 26 | typedef Rounding rounding; |
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| 27 | typedef Checking checking; |
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| 28 | }; |
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| 29 | |
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| 30 | template<class OldInterval, class NewRounding> |
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| 31 | struct change_rounding { |
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| 32 | typedef ... type; |
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| 33 | }; |
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| 34 | |
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| 35 | template<class OldInterval, class NewChecking> |
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| 36 | struct change_checking { |
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| 37 | typedef ... type; |
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| 38 | }; |
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| 39 | |
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| 40 | template<class OldInterval> |
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| 41 | struct unprotect { |
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| 42 | typedef ... type; |
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| 43 | }; |
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| 44 | |
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| 45 | } // namespace interval_lib |
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| 46 | } // namespace numeric |
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| 47 | } // namespace boost</pre> |
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| 48 | |
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| 49 | <p>The <code>policies</code> template should be used whenever the user needs |
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| 50 | to define a policy structure for an <code>interval</code> class. |
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| 51 | <code>change_rounding</code> and <code>change_checking</code> can be used to |
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| 52 | get the type of a new interval by changing one of the policies of an old |
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| 53 | interval; the new type is available thanks to the type definition |
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| 54 | <code>type</code>. Finally, <code>unprotect</code> looks like |
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| 55 | <code>change_rounding</code> and directly changes the rounding of an interval |
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| 56 | to its unprotected version (a better explanation is available <a |
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| 57 | href="rounding.htm#perfexp">here</a>).</p> |
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| 58 | <hr> |
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| 59 | |
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| 60 | <p>Revised: 2003-01-21<br> |
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| 61 | Copyright (c) Guillaume Melquiond, Sylvain Pion, Hervé Brönnimann, 2002.<br> |
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| 62 | Polytechnic University.</p> |
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| 63 | </body> |
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| 64 | </html> |
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