81 lines
2.8 KiB
HTML
81 lines
2.8 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
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"http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<head>
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<meta http-equiv="Content-Language" content="en-us">
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<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
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<link rel="stylesheet" type="text/css" href="../../../../boost.css">
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<title>Policies</title>
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</head>
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<body lang="en">
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<h1>Policies</h1>
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<p>The <code>interval</code> template requires two arguments. The first
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corresponds to the base type chosen for the bounds. And the second defines
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the <a href="rounding.htm">rounding</a> and <a href=
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"checking.htm">checking</a> behaviors of the newly constructed class. This
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second argument is not mandatory but may need some customizations. In order
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to ease the manipulations, some helper templates are provided in
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<code>interval/policies.hpp</code>.</p>
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<pre>
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namespace boost {
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namespace numeric {
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namespace interval_lib {
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template<class Rounding, class Checking>
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struct policies {
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typedef Rounding rounding;
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typedef Checking checking;
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};
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template<class OldInterval, class NewRounding>
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struct change_rounding {
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typedef ... type;
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};
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template<class OldInterval, class NewChecking>
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struct change_checking {
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typedef ... type;
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};
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template<class OldInterval>
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struct unprotect {
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typedef ... type;
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};
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} // namespace interval_lib
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} // namespace numeric
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} // namespace boost
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</pre>
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<p>The <code>policies</code> template should be used whenever the user
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needs to define a policy structure for an <code>interval</code> class.
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<code>change_rounding</code> and <code>change_checking</code> can be used
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to get the type of a new interval by changing one of the policies of an old
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interval; the new type is available thanks to the type definition
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<code>type</code>. Finally, <code>unprotect</code> looks like
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<code>change_rounding</code> and directly changes the rounding of an
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interval to its unprotected version (a better explanation is available
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<a href="rounding.htm#perfexp">here</a>).</p>
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<hr>
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<p><a href="http://validator.w3.org/check?uri=referer"><img border="0" src=
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"../../../../doc/images/valid-html401.png" alt="Valid HTML 4.01 Transitional"
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height="31" width="88"></a></p>
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<p>Revised
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<!--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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<p><i>Copyright © 2002 Guillaume Melquiond, Sylvain Pion, Hervé
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Brönnimann, Polytechnic University</i></p>
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<p><i>Distributed under the Boost Software License, Version 1.0. (See
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accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a>
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or copy at <a href=
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"http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</a>)</i></p>
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</body>
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</html>
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