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72 lines
2.0 KiB
HTML
72 lines
2.0 KiB
HTML
<HTML><HEAD><TITLE>Boost PREPROCESSOR library</TITLE><BODY bgcolor="#FFFFFF">
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<a href="index.htm"><IMG height=86 alt="c++boost.gif (8819 bytes)" src="../../../../c++boost.gif" width=277 align=center></a>
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<hr>
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<H1>#include <<a href="../../../../boost/preprocessor/cat.hpp">boost/preprocessor/cat.hpp</a>></H1>
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<hr>
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<H2><a name="BOOST_PP_CAT">#define BOOST_PP_CAT</a>(X,Y)</H2>
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<P>Delays the catenation of X and Y.</P>
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<P>For example,</P>
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<PRE>
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#define STATIC_ASSERT(EXPR)\
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enum\
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{ <a href="cat.htm#BOOST_PP_CAT">BOOST_PP_CAT</a>(static_check_,__LINE__) = (EXPR) ? 1 : -1\
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};\
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typedef char\
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<a href="cat.htm#BOOST_PP_CAT">BOOST_PP_CAT</a>(static_assert_,__LINE__)\
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[ <a href="cat.htm#BOOST_PP_CAT">BOOST_PP_CAT</a>(static_check_,__LINE__)\
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]
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// ...
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STATIC_ASSERT(sizeof(int) <= sizeof(long));
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</PRE>
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<P>expands to:</P>
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<PRE>
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enum
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{ static_check_152 = (sizeof(int) <= sizeof(long)) ? 1 : -1
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};
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typedef char
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static_assert_152
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[ static_check_152
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];
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</PRE>
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<P>Using <a href="cat.htm#BOOST_PP_CAT">BOOST_PP_CAT</a>() above lets the PP expand the __LINE__. If the above
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code would use the ## operator directly then __LINE__ would not be expanded and
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the above would expand to:</P>
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<PRE>
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enum
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{ static_check___LINE__ = (sizeof(int) <= sizeof(long)) ? 1 : -1
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};
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typedef char
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static_assert___LINE__
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[ static_check___LINE__
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];
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</PRE>
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<hr>
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<H2><a name="BOOST_PREPROCESSOR_CAT">#define BOOST_PREPROCESSOR_CAT</a>(X,Y)</H2>
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<P>Obsolete. Use <a href="cat.htm#BOOST_PP_CAT">BOOST_PP_CAT</a>().</P>
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<hr>
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<p>(C) Copyright Housemarque Oy 2002</p>
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<p>Permission to copy, use, modify, sell and distribute this document is granted
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provided this copyright notice appears in all copies. This document is provided
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"as is" without express or implied warranty, and with no claim as to its suitability
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for any purpose.</p>
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<p>Generated: <!--webbot bot="Timestamp" s-type="EDITED" s-format="%d %b %Y" startspan --><!--webbot bot="Timestamp" endspan i-checksum="15246" --></p>
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</BODY></HTML> |