| 1 | // Boost.TypeErasure library |
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| 2 | // |
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| 3 | // Copyright 2011 Steven Watanabe |
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| 4 | // |
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| 5 | // Distributed under the Boost Software License Version 1.0. (See |
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| 6 | // accompanying file LICENSE_1_0.txt or copy at |
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| 7 | // http://www.boost.org/LICENSE_1_0.txt) |
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| 8 | // |
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| 9 | // $Id$ |
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| 10 | |
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| 11 | #include <boost/type_erasure/operators.hpp> |
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| 12 | #include <typeinfo> |
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| 13 | |
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| 14 | namespace mpl = boost::mpl; |
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| 15 | using namespace boost::type_erasure; |
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| 16 | |
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| 17 | //[concept_map1 |
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| 18 | /*` |
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| 19 | Sometimes it is useful to non-intrusively adapt a |
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| 20 | type to model a concept. For example, suppose that |
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| 21 | we want to make `std::type_info` model __less_than_comparable. |
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| 22 | To do this, we simply specialize the concept definition. |
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| 23 | */ |
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| 24 | namespace boost { |
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| 25 | namespace type_erasure { |
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| 26 | |
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| 27 | template<> |
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| 28 | struct less_than_comparable<std::type_info> |
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| 29 | { |
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| 30 | static bool apply(const std::type_info& lhs, const std::type_info& rhs) |
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| 31 | { return lhs.before(arg: rhs) != 0; } |
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| 32 | }; |
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| 33 | |
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| 34 | } |
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| 35 | } |
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| 36 | |
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| 37 | /*` |
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| 38 | [note Most, but not all of the builtin concepts can be specialized. |
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| 39 | Constructors, destructors, and RTTI need special treatment from the |
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| 40 | library and cannot be specialized. Only primitive concepts can |
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| 41 | be specialized, so the iterator concepts are also out.] |
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| 42 | */ |
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| 43 | |
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| 44 | //] |
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| 45 | |
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| 46 | //[concept_map |
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| 47 | //` (For the source of the examples in this section see |
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| 48 | //` [@boost:/libs/type_erasure/example/concept_map.cpp concept_map.cpp]) |
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| 49 | //` [concept_map1] |
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| 50 | //] |
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| 51 | |
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