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docs: optional<T> == nont_t requirements

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Andrzej Krzemienski
2014-06-08 20:51:55 +02:00
parent befd3970d7
commit 07bdbc3743
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2
doc/13_relational_operators.qbk
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@ -29,6 +29,8 @@ This mixed comparison has a practical interpretation, which is occasionally usef
In the above example, the meaning of the comparison is 'user chose number 2'. If user chose nothing, he didn't choose number 2.
In case where `optional<T>` is compared to `none`, it is not required that `T` be __SGI_EQUALITY_COMPARABLE__.
In a similar manner, type `optional<T>` is __SGI_LESS_THAN_COMPARABLE__ whenever `T` is __SGI_LESS_THAN_COMPARABLE__. The optional object containing no value is compared less than any value of `T`. To illustrate this, if the default ordering of `size_t` is {`0`, `1`, `2`, ...}, the default ordering of `optional<size_t>` is {`boost::none`, `0`, `1`, `2`, ...}. This order does not have a practical interpretation. The goal is to have any semantically correct default ordering in order for `optional<T>` to be usable in ordered associative containers (wherever `T` is usable).
Mixed relational operators are the only case where the contained value of an optional object can be inspected without the usage of value accessing function (`operator*`, `value`, `value_or`).

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doc/html/boost_optional/tutorial/relational_operators.html
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@ -71,6 +71,11 @@
In the above example, the meaning of the comparison is 'user chose number
2'. If user chose nothing, he didn't choose number 2.
</p>
<p>
In case where <code class="computeroutput"><span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span></code> is
compared to <code class="computeroutput"><span class="identifier">none</span></code>, it is not
required that <code class="computeroutput"><span class="identifier">T</span></code> be <a href="http://www.sgi.com/tech/stl/EqualityComparable.html" target="_top"><code class="computeroutput"><span class="identifier">EqualityComparable</span></code></a>.
</p>
<p>
In a similar manner, type <code class="computeroutput"><span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span></code>
is <a href="http://www.sgi.com/tech/stl/LessThanComparable.html" target="_top"><code class="computeroutput"><span class="identifier">LessThanComparable</span></code></a> whenever <code class="computeroutput"><span class="identifier">T</span></code> is <a href="http://www.sgi.com/tech/stl/LessThanComparable.html" target="_top"><code class="computeroutput"><span class="identifier">LessThanComparable</span></code></a>. The optional

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doc/html/index.html
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@ -133,7 +133,7 @@
</div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"><p><small>Last revised: June 08, 2014 at 14:17:56 GMT</small></p></td>
<td align="left"><p><small>Last revised: June 08, 2014 at 18:14:37 GMT</small></p></td>
<td align="right"><div class="copyright-footer"></div></td>
</tr></table>
<hr>