| |
| [/ Copyright 2005-2008 Daniel James. |
| / Distributed under the Boost Software License, Version 1.0. (See accompanying |
| / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) ] |
| |
| [section:disable Disabling The Extensions] |
| |
| While [classref boost::hash]'s extensions are generally useful, you might want |
| to turn them of in order to check that your code will work with other |
| implementations of TR1. To do this define the macro `BOOST_HASH_NO_EXTENSIONS`. |
| When this macro is defined, only the specialisations detailed |
| in TR1 will be declared. But, if you later undefine the macro and include |
| <[headerref boost/functional/hash.hpp]> then the non-specialised form will be defined |
| - activating the extensions. |
| |
| It is strongly recommended that you never undefine the macro - and only define |
| it so that it applies to the complete translation unit, either by defining it |
| at the beginning of the main source file or, preferably, by using a compiler |
| switch or preference. And you really should never define it in header files. |
| |
| If you are writing a library which has code in the header which requires the |
| extensions, then the best action is to tell users not to define the macro. |
| Their code won't ['require] the macro. |
| |
| Translation units that are compiled with the macro defined will link with units |
| that were compiled without it. This feature has been designed to avoid ODR |
| violations. |
| |
| [endsect] |
