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added missing typename's to docs

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[SVN r9324]
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John Maddock 2001-02-25 12:04:48 +00:00
parent 61243bd15f
commit b5ed77985e
1 changed files with 43 additions and 35 deletions
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call_traits.htm
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@ -34,9 +34,9 @@ specialization or member templates, no benefit will occur from
using call_traits: the call_traits defined types will always be
the same as the existing practice in this case. In addition if
only member templates and not partial template specialisation is
support by the compiler (for example Visual C++ 6) then call_traits
can not be used with array types (although it can be used to
solve the reference to reference problem).</p>
support by the compiler (for example Visual C++ 6) then
call_traits can not be used with array types (although it can be
used to solve the reference to reference problem).</p>
<table border="0" cellpadding="7" cellspacing="1" width="797">
<tr>
@ -79,7 +79,8 @@ solve the reference to reference problem).</p>
</td>
</tr>
<tr>
<td valign="top" width="17%"><p align="center">const T&amp;<br>
<td valign="top" width="17%"><p align="center">const
T&amp;<br>
(return value)</p>
</td>
<td valign="top" width="35%"><p align="center"><code>call_traits&lt;T&gt;::const_reference</code></p>
@ -91,7 +92,8 @@ solve the reference to reference problem).</p>
</td>
</tr>
<tr>
<td valign="top" width="17%"><p align="center">const T&amp;<br>
<td valign="top" width="17%"><p align="center">const
T&amp;<br>
(function parameter)</p>
</td>
<td valign="top" width="35%"><p align="center"><code>call_traits&lt;T&gt;::param_type</code></p>
@ -332,8 +334,8 @@ possible:</p>
<p>The following table shows the effect that call_traits has on
various types, the table assumes that the compiler supports
partial specialization: if it doesn't then all types behave in
the same way as the entry for &quot;myclass&quot;, and call_traits
can not be used with reference or array types.</p>
the same way as the entry for &quot;myclass&quot;, and
call_traits can not be used with reference or array types.</p>
<table border="0" cellpadding="7" cellspacing="1" width="766">
<tr>
@ -388,7 +390,8 @@ can not be used with reference or array types.</p>
</td>
<td valign="top" width="17%"><p align="center">int&amp;</p>
</td>
<td valign="top" width="17%"><p align="center">const int&amp;</p>
<td valign="top" width="17%"><p align="center">const
int&amp;</p>
</td>
<td valign="top" width="17%"><p align="center">int const</p>
</td>
@ -420,7 +423,8 @@ can not be used with reference or array types.</p>
</td>
<td valign="top" width="17%"><p align="center">int&amp;</p>
</td>
<td valign="top" width="17%"><p align="center">const int&amp;</p>
<td valign="top" width="17%"><p align="center">const
int&amp;</p>
</td>
<td valign="top" width="17%"><p align="center">int&amp;</p>
</td>
@ -432,13 +436,17 @@ can not be used with reference or array types.</p>
<td valign="top" width="17%" bgcolor="#C0C0C0"><p
align="center">const int&amp;</p>
</td>
<td valign="top" width="17%"><p align="center">const int&amp;</p>
<td valign="top" width="17%"><p align="center">const
int&amp;</p>
</td>
<td valign="top" width="17%"><p align="center">const int&amp;</p>
<td valign="top" width="17%"><p align="center">const
int&amp;</p>
</td>
<td valign="top" width="17%"><p align="center">const int&amp;</p>
<td valign="top" width="17%"><p align="center">const
int&amp;</p>
</td>
<td valign="top" width="17%"><p align="center">const int&amp;</p>
<td valign="top" width="17%"><p align="center">const
int&amp;</p>
</td>
<td valign="top" width="17%"><p align="center">All
constant-references.</p>
@ -486,8 +494,8 @@ can not be used with reference or array types.</p>
<p>The following class is a trivial class that stores some type T
by value (see the <a href="call_traits_test.cpp">call_traits_test.cpp</a>
file), the aim is to illustrate how each of the available call_traits
typedefs may be used:</p>
file), the aim is to illustrate how each of the available
call_traits typedefs may be used:</p>
<pre>template &lt;class T&gt;
struct contained
@ -523,14 +531,14 @@ problem):</h4>
<pre>template &lt;class Operation&gt;
class binder1st :
public unary_function&lt;Operation::second_argument_type, Operation::result_type&gt;
public unary_function&lt;typename Operation::second_argument_type, typename Operation::result_type&gt;
{
protected:
Operation op;
Operation::first_argument_type value;
typename Operation::first_argument_type value;
public:
binder1st(const Operation&amp; x, const Operation::first_argument_type&amp; y);
Operation::result_type operator()(const Operation::second_argument_type&amp; x) const;
binder1st(const Operation&amp; x, const typename Operation::first_argument_type&amp; y);
typename Operation::result_type operator()(const typename Operation::second_argument_type&amp; x) const;
}; </pre>
<p>Now consider what happens in the relatively common case that
@ -541,7 +549,7 @@ reference to a reference as an argument, and that is not
currently legal. The solution here is to modify <code>operator()</code>
to use call_traits:</p>
<pre>Operation::result_type operator()(call_traits&lt;Operation::second_argument_type&gt;::param_type x) const;</pre>
<pre>typename Operation::result_type operator()(typename call_traits&lt;typename Operation::second_argument_type&gt;::param_type x) const;</pre>
<p>Now in the case that <code>Operation::second_argument_type</code>
is a reference type, the argument is passed as a reference, and
@ -575,9 +583,9 @@ std::pair&lt;
degraded to pointers if the deduced types are arrays, similar
situations occur in the standard binders and adapters: in
principle in any function that &quot;wraps&quot; a temporary
whose type is deduced. Note that the function arguments to make_pair
are not expressed in terms of call_traits: doing so would prevent
template argument deduction from functioning.</p>
whose type is deduced. Note that the function arguments to
make_pair are not expressed in terms of call_traits: doing so
would prevent template argument deduction from functioning.</p>
<h4><a name="ex4"></a>Example 4 (optimising fill):</h4>
@ -666,10 +674,10 @@ be any worse than existing practice.</p>
<p>Pointers follow the same rational as small built-in types.</p>
<p>For reference types the rational follows <a href="#refs">Example
2</a> - references to references are not allowed, so the call_traits
members must be defined such that these problems do not occur.
There is a proposal to modify the language such that &quot;a
reference to a reference is a reference&quot; (issue #106,
2</a> - references to references are not allowed, so the
call_traits members must be defined such that these problems do
not occur. There is a proposal to modify the language such that
&quot;a reference to a reference is a reference&quot; (issue #106,
submitted by Bjarne Stroustrup), call_traits&lt;T&gt;::value_type
and call_traits&lt;T&gt;::param_type both provide the same effect
as that proposal, without the need for a language change (in
@ -687,11 +695,11 @@ struct A
void foo(T t);
};</pre>
<p><font face="Times New Roman">In this case if we instantiate A&lt;int[2]&gt;
then the declared type of the parameter passed to member function
foo is int[2], but it's actual type is const int*, if we try to
use the type T within the function body, then there is a strong
likelyhood that our code will not compile:</font></p>
<p><font face="Times New Roman">In this case if we instantiate
A&lt;int[2]&gt; then the declared type of the parameter passed to
member function foo is int[2], but it's actual type is const int*,
if we try to use the type T within the function body, then there
is a strong likelyhood that our code will not compile:</font></p>
<pre>template &lt;class T&gt;
void A&lt;T&gt;::foo(T t)
@ -706,13 +714,13 @@ declared type:</p>
<pre>template &lt;class T&gt;
struct A
{
void foo(call_traits&lt;T&gt;::value_type t);
void foo(typename call_traits&lt;T&gt;::value_type t);
};
template &lt;class T&gt;
void A&lt;T&gt;::foo(call_traits&lt;T&gt;::value_type t)
void A&lt;T&gt;::foo(typename call_traits&lt;T&gt;::value_type t)
{
call_traits&lt;T&gt;::value_type dup(t); // OK even if T is an array type.
typename call_traits&lt;T&gt;::value_type dup(t); // OK even if T is an array type.
}</pre>
<p>For value_type (return by value), again only a pointer may be