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| 9 | |
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| 10 | <title>Policies</title> |
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| 11 | </head> |
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| 12 | |
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| 13 | <body lang="en"> |
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| 14 | <h1>Policies</h1> |
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| 15 | |
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| 16 | <p>The <code>interval</code> template requires two arguments. The first |
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| 17 | corresponds to the base type chosen for the bounds. And the second defines |
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| 18 | the <a href="rounding.htm">rounding</a> and <a href= |
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| 19 | "checking.htm">checking</a> behaviors of the newly constructed class. This |
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| 20 | second argument is not mandatory but may need some customizations. In order |
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| 21 | to ease the manipulations, some helper templates are provided in |
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| 22 | <code>interval/policies.hpp</code>.</p> |
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| 23 | <pre> |
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| 24 | namespace boost { |
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| 25 | namespace numeric { |
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| 26 | namespace interval_lib { |
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| 27 | |
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| 28 | template<class Rounding, class Checking> |
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| 29 | struct policies { |
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| 30 | typedef Rounding rounding; |
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| 31 | typedef Checking checking; |
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| 32 | }; |
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| 33 | |
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| 34 | template<class OldInterval, class NewRounding> |
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| 35 | struct change_rounding { |
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| 36 | typedef ... type; |
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| 37 | }; |
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| 38 | |
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| 39 | template<class OldInterval, class NewChecking> |
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| 40 | struct change_checking { |
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| 41 | typedef ... type; |
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| 42 | }; |
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| 43 | |
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| 44 | template<class OldInterval> |
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| 45 | struct unprotect { |
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| 46 | typedef ... type; |
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| 47 | }; |
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| 48 | |
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| 49 | } // namespace interval_lib |
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| 50 | } // namespace numeric |
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| 51 | } // namespace boost |
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| 52 | </pre> |
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| 53 | |
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| 54 | <p>The <code>policies</code> template should be used whenever the user |
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| 55 | needs to define a policy structure for an <code>interval</code> class. |
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| 56 | <code>change_rounding</code> and <code>change_checking</code> can be used |
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| 57 | to get the type of a new interval by changing one of the policies of an old |
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| 58 | interval; the new type is available thanks to the type definition |
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| 59 | <code>type</code>. Finally, <code>unprotect</code> looks like |
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| 60 | <code>change_rounding</code> and directly changes the rounding of an |
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| 61 | interval to its unprotected version (a better explanation is available |
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| 62 | <a href="rounding.htm#perfexp">here</a>).</p> |
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| 63 | <hr> |
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| 64 | |
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| 65 | <p><a href="http://validator.w3.org/check?uri=referer"><img border="0" src= |
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| 67 | height="31" width="88"></a></p> |
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| 68 | |
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| 69 | <p>Revised |
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| 70 | <!--webbot bot="Timestamp" s-type="EDITED" s-format="%Y-%m-%d" startspan -->2006-12-24<!--webbot bot="Timestamp" endspan i-checksum="12172" --></p> |
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| 71 | |
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| 72 | <p><i>Copyright © 2002 Guillaume Melquiond, Sylvain Pion, Hervé |
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| 73 | Brönnimann, Polytechnic University</i></p> |
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| 74 | |
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| 75 | <p><i>Distributed under the Boost Software License, Version 1.0. (See |
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| 76 | accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> |
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| 77 | or copy at <a href= |
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| 78 | "http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</a>)</i></p> |
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| 79 | </body> |
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| 80 | </html> |
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