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const_pointer_cast added.

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[SVN r19147]
This commit is contained in:
Peter Dimov
2003-07-16 11:51:12 +00:00
parent 7c36a640ae
commit 192970b3b8
5 changed files with 106 additions and 0 deletions
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shared_ptr.htm
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@@ -142,6 +142,9 @@ void bad()
template<class T, class U>
shared_ptr&lt;T&gt; <A href="#static_pointer_cast" >static_pointer_cast</A>(shared_ptr&lt;U&gt; const &amp; r); // never throws
template&lt;class T, class U&gt;
shared_ptr&lt;T&gt; <A href="#const_pointer_cast" >const_pointer_cast</A>(shared_ptr&lt;U&gt; const &amp; r); // never throws
template&lt;class T, class U&gt;
shared_ptr&lt;T&gt; <A href="#dynamic_pointer_cast" >dynamic_pointer_cast</A>(shared_ptr&lt;U&gt; const &amp; r); // never throws
@@ -473,6 +476,21 @@ q = p;
<p>will eventually result in undefined behavior, attempting to delete the same
object twice.</p>
</BLOCKQUOTE>
<h3><a name="const_pointer_cast">const_pointer_cast</a></h3>
<pre>template&lt;class T, class U&gt;
shared_ptr&lt;T&gt; const_pointer_cast(shared_ptr&lt;U&gt; const &amp; r); // never throws</pre>
<BLOCKQUOTE>
<P><STRONG>Requires:</STRONG> The expression <code>const_cast&lt;T*&gt;(r.get())</code>
must be well-formed.</P>
<P><B>Returns:</B> If <b>r</b> is <i>empty</i>, an <i>empty</i> <b>shared_ptr&lt;T&gt;</b>;
otherwise, a <STRONG>shared_ptr&lt;T&gt;</STRONG> object that stores a copy of <code>
const_cast&lt;T*&gt;(r.get())</code> and <i>shares ownership</i> with <b>r</b>.</P>
<P><B>Throws:</B> nothing.</P>
<P><B>Notes:</B> the seemingly equivalent expression</P>
<p><code>shared_ptr&lt;T&gt;(const_cast&lt;T*&gt;(r.get()))</code></p>
<p>will eventually result in undefined behavior, attempting to delete the same
object twice.</p>
</BLOCKQUOTE>
<h3><a name="dynamic_pointer_cast">dynamic_pointer_cast</a></h3>
<pre>template&lt;class T, class U&gt;
shared_ptr&lt;T&gt; dynamic_pointer_cast(shared_ptr&lt;U&gt; const &amp; r);</pre>