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Subject: [Boost-commit] svn:boost r77080 - in trunk/libs/utility/identity_type: doc doc/html test
From: lorcaminiti_at_[hidden]
Date: 2012-02-20 15:17:08

Author: lcaminiti
Date: 2012-02-20 15:17:07 EST (Mon, 20 Feb 2012)
New Revision: 77080
URL: http://svn.boost.org/trac/boost/changeset/77080

Log:
Fixed test indentation and updated docs.
Text files modified:
   trunk/libs/utility/identity_type/doc/html/index.html | 119 +++++++++++++++++++++------------------
   trunk/libs/utility/identity_type/doc/identity_type.qbk | 33 ++++++-----
   trunk/libs/utility/identity_type/test/template.cpp | 10 +-
   trunk/libs/utility/identity_type/test/tmp_assert.cpp | 8 +-
   trunk/libs/utility/identity_type/test/var.cpp | 6 +-
   trunk/libs/utility/identity_type/test/var_error.cpp | 4
   6 files changed, 96 insertions(+), 84 deletions(-)

Modified: trunk/libs/utility/identity_type/doc/html/index.html
==============================================================================
--- trunk/libs/utility/identity_type/doc/html/index.html (original)
+++ trunk/libs/utility/identity_type/doc/html/index.html 2012-02-20 15:17:07 EST (Mon, 20 Feb 2012)
@@ -7,13 +7,14 @@
 This library allows to wrap type expressions within round parenthesis so they
 can be passed to macros even when they contain commas.
 <div class="section boost_utility_identitytype_motivation" title="Motivation"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="boost_utility_identitytype.motivation"></a><a class="link" href="#boost_utility_identitytype.motivation" title="Motivation">Motivation</a></h2></div></div></div>
- Consider the following macro which declares a variable named <code class="computeroutput">var</code>n with the specified
- type (see also var_error.cpp):
+ Consider the following macro which declares a variable named <code class="computeroutput">var</code><code class="literal">n</code>
+ with the specified <code class="literal">type</code> (see also
+ var_error.cpp):
 
<pre class="programlisting">#define VAR(type, n) type var ## n

-VAR( int, 1 ); // OK.
-VAR( std::map<int, char>, 2 ); // Error.
+VAR(int, 1); // OK.
+VAR(std::map<int, char>, 2); // Error.
</pre>
 
 The first macro invocation works correctly declaring a variable named <code class="computeroutput">var1</code> of type <code class="computeroutput">int</code>.
@@ -45,7 +46,7 @@
 the type expression with the commas outside the macro (see also var.cpp):
 
<pre class="programlisting">typedef std::map<int, char> map_type;
-VAR( map_type, 3 ); // OK.
+VAR(map_type, 3); // OK.
</pre>
 
 When this is not possible or desired (e.g., see the function template <code class="computeroutput">f</code> in the section below), the library header
@@ -56,7 +57,7 @@
 
<pre class="programlisting">#include <boost/utility/identity_type.hpp>

-VAR( BOOST_IDENTITY_TYPE((std::map<int, char>)), 4 ); // OK.
+VAR(BOOST_IDENTITY_TYPE((std::map<int, char>)), 4); // OK.
</pre>
 
 This macro expands to an expression that evaluates (at compile-time) to the
@@ -71,14 +72,15 @@
 </div><div class="section boost_utility_identitytype_templates" title="Templates"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="boost_utility_identitytype.templates"></a><a class="link" href="#boost_utility_identitytype.templates" title="Templates">Templates</a></h2></div></div></div>
 This macro must be prefixed by <code class="computeroutput">typename</code>
 when used within templates. For example, let's program a macro that declares
- a function parameter named <code class="computeroutput">arg</code>n
- with the specified type (see also template.cpp):
+ a function parameter named <code class="computeroutput">arg</code><code class="literal">n</code>
+ with the specified <code class="literal">type</code> (see also
+ template.cpp):
 
<pre class="programlisting">#define ARG(type, n) type arg ## n

template<typename T>
void f( // Prefix macro with `typename` in templates.
- ARG( typename BOOST_IDENTITY_TYPE((std::map<int, T>)), 1 )
+ ARG(typename BOOST_IDENTITY_TYPE((std::map<int, T>)), 1)
) {
 std::cout << arg1[0] << std::endl;
}
@@ -87,20 +89,20 @@
<pre class="programlisting">std::map<int, char> a;
a[0] = 'a';

-f<char>(a); // OK.
-// f(a); // But error.
+f<char>(a); // OK...
+// f(a); // ... but error.
</pre>
 
- However, note that the template parameter type <code class="computeroutput">char</code>
- must be explicitly specified when invoking the function <code class="computeroutput">f<char>(a)</code>. In fact,
+ However, note that the template parameter <code class="computeroutput">char</code>
+ must be manually specified when invoking the function <code class="computeroutput">f<char>(a)</code>. In fact,
 when the <code class="computeroutput"><a class="link" href="#BOOST_IDENTITY_TYPE" title="Macro BOOST_IDENTITY_TYPE">BOOST_IDENTITY_TYPE</a></code>
 macro is used to wrap a function template parameter, the template parameter
- can no longer be implicitly determined by the compiler form the function call
- as in <code class="computeroutput">f(a)</code>. (This
- limitation does not apply to class templates because class template parameters
- must always be explicitly specified.) In other words, without using the <code class="computeroutput"><a class="link" href="#BOOST_IDENTITY_TYPE" title="Macro BOOST_IDENTITY_TYPE">BOOST_IDENTITY_TYPE</a></code> macro, C++ would
- normally be able to implicitly deduce the function template parameter as shown
- below:
+ can no longer be automatically deduced by the compiler form the function call
+ as in <code class="computeroutput">f(a)</code>. [<a name="boost_utility_identitytype.templates.f0" href="#ftn.boost_utility_identitytype.templates.f0" class="footnote">2</a>] (This limitation does not apply to class templates because class
+ template parameters must always be explicitly specified.) In other words, without
+ using the <code class="computeroutput"><a class="link" href="#BOOST_IDENTITY_TYPE" title="Macro BOOST_IDENTITY_TYPE">BOOST_IDENTITY_TYPE</a></code>
+ macro, C++ would normally be able to automatically deduce the function template
+ parameter as shown below:
 
<pre class="programlisting">template<typename T>
void g(
@@ -110,14 +112,14 @@
}
</pre>
 
-<pre class="programlisting">g<char>(a); // OK.
-g(a); // Also OK.
+<pre class="programlisting">g<char>(a); // OK...
+g(a); // ... and also OK.
</pre>
 </div><div class="section boost_utility_identitytype_abstract_types" title="Abstract Types"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="boost_utility_identitytype.abstract_types"></a><a class="link" href="#boost_utility_identitytype.abstract_types" title="Abstract Types">Abstract Types</a></h2></div></div></div>
- On some compilers (e.g., GCC), using this macro on abstract types (i.e., a
- class with one or more pure virtual functions) generates a compiler error.
- This can be worked around by manipulating the type adding and removing a reference
- to it.
+ On some compilers (e.g., GCC), using this macro on abstract types (i.e., classes
+ with one or more pure virtual functions) generates a compiler error. This can
+ be worked around by manipulating the type adding and removing a reference to
+ it.
 
 Let's program a macro that performs a static assertion on a <a href="http://en.wikipedia.org/wiki/Template_metaprogramming" target="_top">Template
 Meta-Programming</a> (TMP) meta-function (similarly to Boost.MPL BOOST_MPL_ASSERT). The <code class="computeroutput"><a class="link" href="#BOOST_IDENTITY_TYPE" title="Macro BOOST_IDENTITY_TYPE">BOOST_IDENTITY_TYPE</a></code> macro can be used
@@ -132,7 +134,7 @@
template<typename T, bool b>
struct abstract {
 static const bool value = b;
- virtual void f(T const& x) = 0;
+ virtual void f(T const& x) = 0; // Pure virtual function.
};

TMP_ASSERT(
@@ -147,29 +149,32 @@
</pre>
 </div><div class="section boost_utility_identitytype_annex__usage" title="Annex: Usage"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="boost_utility_identitytype.annex__usage"></a><a class="link" href="#boost_utility_identitytype.annex__usage" title="Annex: Usage">Annex: Usage</a></h2></div></div></div>
 The <code class="computeroutput"><a class="link" href="#BOOST_IDENTITY_TYPE" title="Macro BOOST_IDENTITY_TYPE">BOOST_IDENTITY_TYPE</a></code> macro
- can be used either in the call of the user-defined macro (as shown by the examples
- so far), or internally to the definition of the user macro. When <code class="computeroutput"><a class="link" href="#BOOST_IDENTITY_TYPE" title="Macro BOOST_IDENTITY_TYPE">BOOST_IDENTITY_TYPE</a></code> is used internally,
- the call of the user macro will only have to specify the extra parenthesis
- (see also tmp_assert.cpp):
+ can be used either when calling a user-defined macro (as shown by the examples
+ so far), or internally in the definition of a user-defined macro (as shown
+ below). When <code class="computeroutput"><a class="link" href="#BOOST_IDENTITY_TYPE" title="Macro BOOST_IDENTITY_TYPE">BOOST_IDENTITY_TYPE</a></code>
+ is used in the user macro definition, the call of the user macro will only
+ have to specify the extra parenthesis (see also tmp_assert.cpp):
 
<pre class="programlisting">#define TMP_ASSERT_PAREN(parenthesized_metafunction) \
 /* use `BOOST_IDENTITY_TYPE` in macro definition instead of invocation */ \
 BOOST_STATIC_ASSERT(BOOST_IDENTITY_TYPE(parenthesized_metafunction)::value)

-TMP_ASSERT_PAREN(( boost::is_const<std::map<int, char> const> ));
-TMP_ASSERT( BOOST_IDENTITY_TYPE((boost::is_const<std::map<int, char> const>)) );
+// Specify only extra parenthesis `((...))`.
+TMP_ASSERT_PAREN((boost::is_const<std::map<int, char> const>));
+// Specify both the extra parenthesis `((...))` and `BOOST_IDENTITY_TYPE` macro.
+TMP_ASSERT(BOOST_IDENTITY_TYPE((boost::is_const<std::map<int, char> const>)));
</pre>
 
 However, note that the user will always have to specify
 the extra parenthesis even when the macro parameters contain no comma:
 
-<pre class="programlisting">TMP_ASSERT_PAREN(( boost::is_const<int const> )); // Always extra `()`.
-TMP_ASSERT( boost::is_const<int const> ); // No extra `()` and no macro.
+<pre class="programlisting">TMP_ASSERT_PAREN((boost::is_const<int const>)); // Always extra `((...))`.
+TMP_ASSERT(boost::is_const<int const>); // No extra `((...))` and no macro.
</pre>
 
 In some cases, using <code class="computeroutput"><a class="link" href="#BOOST_IDENTITY_TYPE" title="Macro BOOST_IDENTITY_TYPE">BOOST_IDENTITY_TYPE</a></code>
- internally might provide the best syntax for the user. For example, this is
- the case for <code class="computeroutput">BOOST_MPL_ASSERT</code>
+ within the user macro definition might provide the best syntax for the user.
+ For example, this is the case for <code class="computeroutput">BOOST_MPL_ASSERT</code>
 because the majority of template meta-programming expressions contain unwrapped
 commas so it is less confusing for the user to always specify the extra parenthesis
 <code class="computeroutput">((...))</code> instead of using <code class="computeroutput"><a class="link" href="#BOOST_IDENTITY_TYPE" title="Macro BOOST_IDENTITY_TYPE">BOOST_IDENTITY_TYPE</a></code>:
@@ -181,22 +186,21 @@
));
</pre>
 However, in other situations it might be preferable to not require the extra
- parenthesis in common cases and handle commas as special cases using the <code class="computeroutput"><a class="link" href="#BOOST_IDENTITY_TYPE" title="Macro BOOST_IDENTITY_TYPE">BOOST_IDENTITY_TYPE</a></code>. For example, this
- is the case for <code class="computeroutput">BOOST_LOCAL_FUNCTION</code>
- for which always requiring the extra parenthesis <code class="computeroutput">((...))</code>
- around the types would lead to an unnatural syntax for the local function parameter
- types:
+ parenthesis in the common cases and handle commas as special cases using <code class="computeroutput"><a class="link" href="#BOOST_IDENTITY_TYPE" title="Macro BOOST_IDENTITY_TYPE">BOOST_IDENTITY_TYPE</a></code>. For example, this
+ is the case for BOOST_LOCAL_FUNCTION for which always
+ requiring the extra parenthesis <code class="computeroutput">((...))</code>
+ around the types would lead to an unnatural syntax for the local function signature:
 <pre class="programlisting">int BOOST_LOCAL_FUNCTION( ((int&)) x, ((int&)) y ) { // Unnatural syntax.
 return x + y;
} BOOST_LOCAL_FUNCTION_NAME(add)
</pre>
 Instead requiring the user to specify <code class="computeroutput"><a class="link" href="#BOOST_IDENTITY_TYPE" title="Macro BOOST_IDENTITY_TYPE">BOOST_IDENTITY_TYPE</a></code>
- when needed allows for the more natural syntax <code class="computeroutput">BOOST_LOCAL_FUNCTION(int&
+ only when needed allows for the more natural syntax <code class="computeroutput">BOOST_LOCAL_FUNCTION(int&
 x, int& y)</code> in the common cases when the parameter types
 contain no comma.
 </div><div class="section boost_utility_identitytype_annex__implementation" title="Annex: Implementation"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="boost_utility_identitytype.annex__implementation"></a><a class="link" href="#boost_utility_identitytype.annex__implementation" title="Annex: Implementation">Annex:
 Implementation</a></h2></div></div></div>
- The implementation of this library macro is equivalent to the following: [<a name="boost_utility_identitytype.annex__implementation.f0" href="#ftn.boost_utility_identitytype.annex__implementation.f0" class="footnote">2</a>]
+ The implementation of this library macro is equivalent to the following: [<a name="boost_utility_identitytype.annex__implementation.f0" href="#ftn.boost_utility_identitytype.annex__implementation.f0" class="footnote">3</a>]
 <pre class="programlisting">#include <boost/type_traits/function_traits.hpp>

#define BOOST_IDENTITY_TYPE(parenthesized_type) \
@@ -204,24 +208,29 @@
</pre>
 Essentially, the type is wrapped between round parenthesis <code class="computeroutput">(std::map<int,
 char>)</code>
- so it can be passed as a macro parameter even if it contain commas. Then the
- parenthesized type is transformed into the type of a function returning <code class="computeroutput">void</code> and with the specified type as the type
- of the first and only argument <code class="computeroutput">void
+ so it can be passed as a single macro parameter even if it contains commas.
+ Then the parenthesized type is transformed into the type of a function returning
+ <code class="computeroutput">void</code> and with the specified type
+ as the type of the first and only argument <code class="computeroutput">void
 (std::map<int, char>)</code>. Finally, the type of the first argument
- <code class="computeroutput">arg1_type</code> is extracted therefore
- obtaining the original type from the parenthesized type (effectively stripping
- the parenthesis from around the type).
+ <code class="computeroutput">arg1_type</code> is extracted at compile-time
+ using the <code class="computeroutput">function_traits</code> meta-function
+ therefore obtaining the original type from the parenthesized type (effectively
+ stripping the extra parenthesis from around the specified type).
 </div><div class="section reference" title="Reference"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="reference"></a>Reference</h2></div></div></div><div class="section header_boost_utility_identity_type_hpp" title="Header <boost/utility/identity_type.hpp>"><div class="titlepage"><div><div><h3 class="title"><a name="header.boost.utility.identity_type_hpp"></a>Header <boost/utility/identity_type.hpp></h3></div></div></div>Wrap type expressions with round parenthesis so they can be passed to macros even if they contain commas. <pre class="synopsis">

<a class="link" href="#BOOST_IDENTITY_TYPE" title="Macro BOOST_IDENTITY_TYPE">BOOST_IDENTITY_TYPE</a>(parenthesized_type)</pre><div class="refentry" title="Macro BOOST_IDENTITY_TYPE"><a name="BOOST_IDENTITY_TYPE"></a><div class="titlepage"></div><div class="refnamediv"><h2>Macro BOOST_IDENTITY_TYPE</h2>BOOST_IDENTITY_TYPE â€” This macro allows to wrap the specified type expression within extra round parenthesis so the type can be passed as a single macro parameter even if it contains commas (not already wrapped within round parenthesis). </div><h2 class="refsynopsisdiv-title">Synopsis</h2><div class="refsynopsisdiv"><pre class="synopsis">// In header: <<a class="link" href="#header.boost.utility.identity_type_hpp" title="Header <boost/utility/identity_type.hpp>">boost/utility/identity_type.hpp</a>>

-BOOST_IDENTITY_TYPE(parenthesized_type)</pre></div><div class="refsect1" title="Description"><a name="id571742"></a><h2>Description</h2>Parameters: <div class="informaltable"><table class="table"><colgroup><col><col></colgroup><tbody><tr><td><code class="computeroutput">parenthesized_type</code></td><td>The type expression to be passed as macro parameter wrapped by a single set of round parenthesis <code class="computeroutput">(...)</code>. This type expression can contain an arbitrary number of commas. </td></tr></tbody></table></div>
+BOOST_IDENTITY_TYPE(parenthesized_type)</pre></div><div class="refsect1" title="Description"><a name="id512092"></a><h2>Description</h2>Parameters: <div class="informaltable"><table class="table"><colgroup><col><col></colgroup><tbody><tr><td><code class="computeroutput">parenthesized_type</code></td><td>The type expression to be passed as macro parameter wrapped by a single set of round parenthesis <code class="computeroutput">(...)</code>. This type expression can contain an arbitrary number of commas. </td></tr></tbody></table></div>
This macro works on any C++03 compiler (it does not require variadic macros).This macro must be prefixed by <code class="computeroutput">typename</code> when used within templates. However, the compiler will not be able to automatically determine function template parameters when they are wrapped with this macro (these parameters need to be explicitly specified when calling the function template).On some compilers (like GCC), using this macro on an abstract types requires to add and remove a reference to the type. </div></div></div></div><div class="footnotes"> <hr width="100" align="left"><div class="footnote">[<a id="ftn.boost_utility_identitytype.solution.f0" href="#boost_utility_identitytype.solution.f0" class="para">1</a>] 
- Using variadic macros, it would be possible to use a single set of parenthesis
- <code class="computeroutput">BOOST_IDENTITY_TYPE(</code>type<code class="computeroutput">)</code> instead of two <code class="computeroutput">BOOST_IDENTITY_TYPE((</code>type<code class="computeroutput">))</code>
- but variadic macros are not part of C++03 (even if nowadays they are supported
- by most modern compilers and they are also part of C++11).
- </div><div class="footnote">[<a id="ftn.boost_utility_identitytype.annex__implementation.f0" href="#boost_utility_identitytype.annex__implementation.f0" class="para">2</a>] 
+ Using variadic macros, it would be possible to require a single set of extra
+ parenthesis <code class="computeroutput">BOOST_IDENTITY_TYPE(</code><code class="literal">type</code><code class="computeroutput">)</code> instead of two <code class="computeroutput">BOOST_IDENTITY_TYPE((</code><code class="literal">type</code><code class="computeroutput">))</code> but variadic macros are not part of C++03
+ (even if nowadays they are supported by most modern compilers and they are
+ also part of C++11).
+ </div><div class="footnote">[<a id="ftn.boost_utility_identitytype.templates.f0" href="#boost_utility_identitytype.templates.f0" class="para">2</a>] 
+ This is because the implementation of <code class="computeroutput"><a class="link" href="#BOOST_IDENTITY_TYPE" title="Macro BOOST_IDENTITY_TYPE">BOOST_IDENTITY_TYPE</a></code>
+ wraps the specified type within a meta-function.
+ </div><div class="footnote">[<a id="ftn.boost_utility_identitytype.annex__implementation.f0" href="#boost_utility_identitytype.annex__implementation.f0" class="para">3</a>] 
 There is absolutely no guarantee that the macro is actually implemented using
 the code listed in this documentation. This code is for explanatory purposes
 only.

Modified: trunk/libs/utility/identity_type/doc/identity_type.qbk
==============================================================================
--- trunk/libs/utility/identity_type/doc/identity_type.qbk (original)
+++ trunk/libs/utility/identity_type/doc/identity_type.qbk 2012-02-20 15:17:07 EST (Mon, 20 Feb 2012)
@@ -28,7 +28,7 @@

[section Motivation]

-Consider the following macro which declares a variable named `var`/n/ with the specified /type/ (see also [@../../test/var_error.cpp =var_error.cpp=]):
+Consider the following macro which declares a variable named `var`[^['n]] with the specified [^['type]] (see also [@../../test/var_error.cpp =var_error.cpp=]):

[var_error]

@@ -68,7 +68,7 @@

This macro works on any [@http://www.open-std.org/JTC1/SC22/WG21/docs/standards C++03] compiler (because it does not use [@http://en.wikipedia.org/wiki/Variadic_macro variadic macros]).
[footnote
-Using variadic macros, it would be possible to use a single set of parenthesis `BOOST_IDENTITY_TYPE(`/type/`)` instead of two `BOOST_IDENTITY_TYPE((`/type/`))` but variadic macros are not part of C++03 (even if nowadays they are supported by most modern compilers and they are also part of C++11).
+Using variadic macros, it would be possible to require a single set of extra parenthesis `BOOST_IDENTITY_TYPE(`[^['type]]`)` instead of two `BOOST_IDENTITY_TYPE((`[^['type]]`))` but variadic macros are not part of C++03 (even if nowadays they are supported by most modern compilers and they are also part of C++11).
]

[endsect]
@@ -76,15 +76,18 @@
[section Templates]

This macro must be prefixed by `typename` when used within templates.
-For example, let's program a macro that declares a function parameter named `arg`/n/ with the specified /type/ (see also [@../../test/template.cpp =template.cpp=]):
+For example, let's program a macro that declares a function parameter named `arg`[^['n]] with the specified [^['type]] (see also [@../../test/template.cpp =template.cpp=]):

[template_f_decl]
[template_f_call]

-However, note that the template parameter type `char` must be explicitly specified when invoking the function `f<char>(a)`.
-In fact, when the [macroref BOOST_IDENTITY_TYPE] macro is used to wrap a function template parameter, the template parameter can no longer be implicitly determined by the compiler form the function call as in `f(a)`.
+However, note that the template parameter `char` must be manually specified when invoking the function `f<char>(a)`.
+In fact, when the [macroref BOOST_IDENTITY_TYPE] macro is used to wrap a function template parameter, the template parameter can no longer be automatically deduced by the compiler form the function call as in `f(a)`.
+[footnote
+This is because the implementation of [macroref BOOST_IDENTITY_TYPE] wraps the specified type within a meta-function.
+]
(This limitation does not apply to class templates because class template parameters must always be explicitly specified.)
-In other words, without using the [macroref BOOST_IDENTITY_TYPE] macro, C++ would normally be able to implicitly deduce the function template parameter as shown below:
+In other words, without using the [macroref BOOST_IDENTITY_TYPE] macro, C++ would normally be able to automatically deduce the function template parameter as shown below:

[template_g_decl]
[template_g_call]
@@ -93,7 +96,7 @@

[section Abstract Types]

-On some compilers (e.g., GCC), using this macro on abstract types (i.e., a class with one or more pure virtual functions) generates a compiler error.
+On some compilers (e.g., GCC), using this macro on abstract types (i.e., classes with one or more pure virtual functions) generates a compiler error.
This can be worked around by manipulating the type adding and removing a reference to it.

Let's program a macro that performs a static assertion on a [@http://en.wikipedia.org/wiki/Template_metaprogramming Template Meta-Programming] (TMP) meta-function (similarly to Boost.MPL [@http://www.boost.org/doc/libs/1_36_0/libs/mpl/doc/refmanual/assert.html `BOOST_MPL_ASSERT`]).
@@ -106,8 +109,8 @@

[section Annex: Usage]

-The [macroref BOOST_IDENTITY_TYPE] macro can be used either in the call of the user-defined macro (as shown by the examples so far), or internally to the definition of the user macro.
-When [macroref BOOST_IDENTITY_TYPE] is used internally, the call of the user macro will only have to specify the extra parenthesis (see also [@../../test/tmp_assert.cpp =tmp_assert.cpp=]):
+The [macroref BOOST_IDENTITY_TYPE] macro can be used either when calling a user-defined macro (as shown by the examples so far), or internally in the definition of a user-defined macro (as shown below).
+When [macroref BOOST_IDENTITY_TYPE] is used in the user macro definition, the call of the user macro will only have to specify the extra parenthesis (see also [@../../test/tmp_assert.cpp =tmp_assert.cpp=]):

[tmp_assert_alternative]

@@ -115,7 +118,7 @@

[tmp_assert_alternative_always]

-In some cases, using [macroref BOOST_IDENTITY_TYPE] internally might provide the best syntax for the user.
+In some cases, using [macroref BOOST_IDENTITY_TYPE] within the user macro definition might provide the best syntax for the user.
For example, this is the case for `BOOST_MPL_ASSERT` because the majority of template meta-programming expressions contain unwrapped commas so it is less confusing for the user to always specify the extra parenthesis `((...))` instead of using [macroref BOOST_IDENTITY_TYPE]:

 BOOST_MPL_ASSERT(( // Natural syntax.
@@ -125,14 +128,14 @@
>
 ));

-However, in other situations it might be preferable to not require the extra parenthesis in common cases and handle commas as special cases using the [macroref BOOST_IDENTITY_TYPE].
-For example, this is the case for `BOOST_LOCAL_FUNCTION` for which always requiring the extra parenthesis `((...))` around the types would lead to an unnatural syntax for the local function parameter types:
+However, in other situations it might be preferable to not require the extra parenthesis in the common cases and handle commas as special cases using [macroref BOOST_IDENTITY_TYPE].
+For example, this is the case for [@http://www.boost.org/libs/local_function `BOOST_LOCAL_FUNCTION`] for which always requiring the extra parenthesis `((...))` around the types would lead to an unnatural syntax for the local function signature:

 int BOOST_LOCAL_FUNCTION( ((int&)) x, ((int&)) y ) { // Unnatural syntax.
 return x + y;
 } BOOST_LOCAL_FUNCTION_NAME(add)

-Instead requiring the user to specify [macroref BOOST_IDENTITY_TYPE] when needed allows for the more natural syntax `BOOST_LOCAL_FUNCTION(int& x, int& y)` in the common cases when the parameter types contain no comma.
+Instead requiring the user to specify [macroref BOOST_IDENTITY_TYPE] only when needed allows for the more natural syntax `BOOST_LOCAL_FUNCTION(int& x, int& y)` in the common cases when the parameter types contain no comma.

[endsect]

@@ -149,9 +152,9 @@
 #define BOOST_IDENTITY_TYPE(parenthesized_type) \
 boost::function_traits<void parenthesized_type>::arg1_type

-Essentially, the type is wrapped between round parenthesis `(std::map<int, char>)` so it can be passed as a macro parameter even if it contain commas.
+Essentially, the type is wrapped between round parenthesis `(std::map<int, char>)` so it can be passed as a single macro parameter even if it contains commas.
Then the parenthesized type is transformed into the type of a function returning `void` and with the specified type as the type of the first and only argument `void (std::map<int, char>)`.
-Finally, the type of the first argument `arg1_type` is extracted therefore obtaining the original type from the parenthesized type (effectively stripping the parenthesis from around the type).
+Finally, the type of the first argument `arg1_type` is extracted at compile-time using the `function_traits` meta-function therefore obtaining the original type from the parenthesized type (effectively stripping the extra parenthesis from around the specified type).

[endsect]

Modified: trunk/libs/utility/identity_type/test/template.cpp
==============================================================================
--- trunk/libs/utility/identity_type/test/template.cpp (original)
+++ trunk/libs/utility/identity_type/test/template.cpp 2012-02-20 15:17:07 EST (Mon, 20 Feb 2012)
@@ -14,7 +14,7 @@

template<typename T>
void f( // Prefix macro with `typename` in templates.
- ARG( typename BOOST_IDENTITY_TYPE((std::map<int, T>)), 1 )
+ ARG(typename BOOST_IDENTITY_TYPE((std::map<int, T>)), 1)
) {
 std::cout << arg1[0] << std::endl;
}
@@ -34,13 +34,13 @@
 std::map<int, char> a;
 a[0] = 'a';

- f<char>(a); // OK.
- // f(a); // But error.
+ f<char>(a); // OK...
+ // f(a); // ... but error.
 //]

 //[template_g_call
- g<char>(a); // OK.
- g(a); // Also OK.
+ g<char>(a); // OK...
+ g(a); // ... and also OK.
 //]

 return 0;

Modified: trunk/libs/utility/identity_type/test/tmp_assert.cpp
==============================================================================
--- trunk/libs/utility/identity_type/test/tmp_assert.cpp (original)
+++ trunk/libs/utility/identity_type/test/tmp_assert.cpp 2012-02-20 15:17:07 EST (Mon, 20 Feb 2012)
@@ -39,14 +39,14 @@
BOOST_STATIC_ASSERT(BOOST_IDENTITY_TYPE(parenthesized_metafunction)::value)

// Specify only extra parenthesis `((...))`.
-TMP_ASSERT_PAREN(( boost::is_const<std::map<int, char> const> ));
+TMP_ASSERT_PAREN((boost::is_const<std::map<int, char> const>));
// Specify both the extra parenthesis `((...))` and `BOOST_IDENTITY_TYPE` macro.
-TMP_ASSERT( BOOST_IDENTITY_TYPE((boost::is_const<std::map<int, char> const>)) );
+TMP_ASSERT(BOOST_IDENTITY_TYPE((boost::is_const<std::map<int, char> const>)));
//]

//[tmp_assert_alternative_always
-TMP_ASSERT_PAREN(( boost::is_const<int const> )); // Always extra `((...))`.
-TMP_ASSERT( boost::is_const<int const> ); // No extra `((...))` and no macro.
+TMP_ASSERT_PAREN((boost::is_const<int const>)); // Always extra `((...))`.
+TMP_ASSERT(boost::is_const<int const>); // No extra `((...))` and no macro.
//]

int main() { return 0; }

Modified: trunk/libs/utility/identity_type/test/var.cpp
==============================================================================
--- trunk/libs/utility/identity_type/test/var.cpp (original)
+++ trunk/libs/utility/identity_type/test/var.cpp 2012-02-20 15:17:07 EST (Mon, 20 Feb 2012)
@@ -9,17 +9,17 @@

#define VAR(type, n) type var ## n

-VAR( int, 1 ); // OK.
+VAR(int, 1); // OK.

//[var_typedef
typedef std::map<int, char> map_type;
-VAR( map_type, 3 ); // OK.
+VAR(map_type, 3); // OK.
//]

//[var_ok
#include <boost/utility/identity_type.hpp>

-VAR( BOOST_IDENTITY_TYPE((std::map<int, char>)), 4 ); // OK.
+VAR(BOOST_IDENTITY_TYPE((std::map<int, char>)), 4); // OK.
//]

int main() { return 0; }

Modified: trunk/libs/utility/identity_type/test/var_error.cpp
==============================================================================
--- trunk/libs/utility/identity_type/test/var_error.cpp (original)
+++ trunk/libs/utility/identity_type/test/var_error.cpp 2012-02-20 15:17:07 EST (Mon, 20 Feb 2012)
@@ -10,8 +10,8 @@
//[var_error
#define VAR(type, n) type var ## n

-VAR( int, 1 ); // OK.
-VAR( std::map<int, char>, 2 ); // Error.
+VAR(int, 1); // OK.
+VAR(std::map<int, char>, 2); // Error.
//]

int main() { return 0; }

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