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Added trivial docs change, based on user suggestion, and brought example code into synch.

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[SVN r34874]
This commit is contained in:
John Maddock
2006-08-11 18:14:13 +00:00
parent 7a0a3fbf32
commit 66dd3d2595
3 changed files with 13 additions and 7 deletions
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11
doc/static_assert.qbk
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@ -49,11 +49,12 @@ be an unsigned type. We can verify this at compile time as follows:
#include <climits> #include <climits>
#include <cwchar> #include <cwchar>
#include <limits>
#include <boost/static_assert.hpp> #include <boost/static_assert.hpp>
namespace my_conditions { namespace my_conditions {
BOOST_STATIC_ASSERT(sizeof(int) * CHAR_BIT >= 32); BOOST_STATIC_ASSERT(std::numeric_limits<int>::digits >= 32);
BOOST_STATIC_ASSERT(WCHAR_MIN >= 0); BOOST_STATIC_ASSERT(WCHAR_MIN >= 0);
} // namespace my_conditions } // namespace my_conditions
@ -61,7 +62,7 @@ be an unsigned type. We can verify this at compile time as follows:
The use of the namespace my_conditions here requires some comment. The use of the namespace my_conditions here requires some comment.
The macro `BOOST_STATIC_ASSERT` works by generating an typedef declaration, The macro `BOOST_STATIC_ASSERT` works by generating an typedef declaration,
and since the typedef must have a name, the macro generates one automatically by and since the typedef must have a name, the macro generates one automatically by
mangling a stub name with the value of __LINE__. When `BOOST_STATIC_ASSERT` is mangling a stub name with the value of `__LINE__`. When `BOOST_STATIC_ASSERT` is
used at either class or function scope then each use of `BOOST_STATIC_ASSERT` used at either class or function scope then each use of `BOOST_STATIC_ASSERT`
is guaranteed to produce a name unique to that scope (provided you only use is guaranteed to produce a name unique to that scope (provided you only use
the macro once on each line). However when used in a header at namespace the macro once on each line). However when used in a header at namespace
@ -128,8 +129,8 @@ using something like this:
class myclass class myclass
{ {
private: private:
BOOST_STATIC_ASSERT(sizeof(UnsignedInt) * CHAR_BIT >= 16); BOOST_STATIC_ASSERT((std::numeric_limits<UnsignedInt>::digits >= 16)
BOOST_STATIC_ASSERT(std::numeric_limits<UnsignedInt>::is_specialized && std::numeric_limits<UnsignedInt>::is_specialized
&& std::numeric_limits<UnsignedInt>::is_integer && std::numeric_limits<UnsignedInt>::is_integer
&& !std::numeric_limits<UnsignedInt>::is_signed); && !std::numeric_limits<UnsignedInt>::is_signed);
public: public:
@ -216,3 +217,5 @@ working at namespace, function, and class scope outweighed the ugliness of a mac
] ]
[endsect] [endsect]

4
static_assert_example_1.cpp
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@ -7,6 +7,7 @@
#include <climits> #include <climits>
#include <cwchar> #include <cwchar>
#include <limits>
#include <boost/static_assert.hpp> #include <boost/static_assert.hpp>
#if !defined(WCHAR_MIN) #if !defined(WCHAR_MIN)
@ -16,7 +17,7 @@
namespace boost{ namespace boost{
namespace my_conditions { namespace my_conditions {
BOOST_STATIC_ASSERT(sizeof(int) * CHAR_BIT >= 32); BOOST_STATIC_ASSERT(std::numeric_limits<int>::digits >= 32);
BOOST_STATIC_ASSERT(WCHAR_MIN >= 0); BOOST_STATIC_ASSERT(WCHAR_MIN >= 0);
} // namespace my_conditions } // namespace my_conditions
@ -30,3 +31,4 @@ int main()

5
static_assert_example_3.cpp
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@ -13,8 +13,8 @@ template <class UnsignedInt>
class myclass class myclass
{ {
private: private:
BOOST_STATIC_ASSERT(sizeof(UnsignedInt) * CHAR_BIT >= 16); BOOST_STATIC_ASSERT((std::numeric_limits<UnsignedInt>::digits >= 16)
BOOST_STATIC_ASSERT(std::numeric_limits<UnsignedInt>::is_specialized && std::numeric_limits<UnsignedInt>::is_specialized
&& std::numeric_limits<UnsignedInt>::is_integer && std::numeric_limits<UnsignedInt>::is_integer
&& !std::numeric_limits<UnsignedInt>::is_signed); && !std::numeric_limits<UnsignedInt>::is_signed);
public: public:
@ -30,3 +30,4 @@ int main()
return 0; return 0;
} }