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Add issues list to d0355r1

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Howard Hinnant
2016-10-15 21:02:01 -04:00
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@@ -42,6 +42,7 @@ Document number: D0355R1<br/>
<li><a href="#Revision">Revision History</a></li> <li><a href="#Revision">Revision History</a></li>
<li><a href="#Introduction">Introduction</a></li> <li><a href="#Introduction">Introduction</a></li>
<li><a href="#Description">Description</a></li> <li><a href="#Description">Description</a></li>
<li><a href="#Issues">Issues</a></li>
<li><a href="#Wording">Proposed Wording</a></li> <li><a href="#Wording">Proposed Wording</a></li>
<li><a href="#Acknowledgements">Acknowledgements</a></li> <li><a href="#Acknowledgements">Acknowledgements</a></li>
<li><a href="#References">References</a></li> <li><a href="#References">References</a></li>
@@ -569,6 +570,72 @@ please see:
<a href="http://howardhinnant.github.io/date/iso_week.html">http://howardhinnant.github.io/date/iso_week.html</a> <a href="http://howardhinnant.github.io/date/iso_week.html">http://howardhinnant.github.io/date/iso_week.html</a>
</blockquote> </blockquote>
<a name="Issues"></a><h2>Issues</h2>
<p>
This is a collection of issues that could be changed one way or the other with this
proposal.
</p>
<ol>
<li>
<p>
Can the database be updated by the program while the program is running?
</p>
<p>
This is probably the most important issue to be decided. This decision, one way or
the other, leads (or doesn't) to many other decisions. If the database can be updated
while the program is running:
</p>
<ol type="a">
<li>Is the cleint responsible for thread safety issues? This proposal says yes.</li>
<li>What is the format of the database? This proposal says it is the text format
of the IANA database.</li>
<li>Can the database be updated to the latest version at a remote server on application
startup? This proposal says yes. This means Egypt-like time-zone changes (3 days
notice) can be handled seamlessly.</li>
</ol>
<p>
Not allowing the database to be dynamically updated is by far the simpler solution.
This proposal shows you what dynamic updating could look like. It is far easier to
remove this feature from a proposal than to add it. This proposal is designed in such
a way that it is trivial to remove this functionality.
</p>
</li>
<li>
<p>
Currently this library passes <code>time_zone</code>s around with
<code>const time_zone*</code>. Each <code>time_zone</code> is a non-copyable singleton
in the application (much like a <code>type_info</code>). Passing them around by pointers
allows syntax such as:
</p>
<blockquote><pre>
auto tz = current_zone();
cout &lt;&lt; tz-&gt;name() &lt;&lt; '\n';
</pre></blockquote>
<p>
But source functions such as <code>current_zone</code> and <code>locate_zone</code>
<i>never</i> return <code>nullptr</code>. So it has been suggested that the library
traffic in <code>const time_zone&amp;</code> instead. This would change the above
code snippet to:
</p>
<blockquote><pre>
auto&amp; tz = current_zone();
cout &lt;&lt; tz.name() &lt;&lt; '\n';
</pre></blockquote>
<p>
Either solution is workable. And whichever we choose, the client can get the other
with <code>*current_zone()</code> or <code>&amp;current_zone()</code>. And whichever
we choose, we <i>will</i> make the library API self-consistent so that things like
the following work no matter what with this syntax:
</p>
<blockquote><pre>
cout &lt;&lt; make_zoned(current_zone(), system_clock::now()) &lt;&lt; '\n';
</pre></blockquote>
</li>
</ol>
<a name="Wording"></a><h2>Proposed Wording</h2> <a name="Wording"></a><h2>Proposed Wording</h2>
<blockquote class = note><p> <blockquote class = note><p>