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Clarify some of the iostreams stuff. 

llvm-svn: 43766
This commit is contained in:
Bill Wendling 2007-11-06 09:36:34 +00:00
parent d5d59ad634
commit 56235a28ce
1 changed files with 13 additions and 13 deletions
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26
llvm/docs/CodingStandards.html
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@ -505,14 +505,14 @@ library. There are two problems with this:</p>
<ol>
<li>The time to run the static c'tors impacts startup time of
applications&mdash;a critical time for gui apps.</li>
applications&mdash;a critical time for GUI apps.</li>
<li>The static c'tors cause the app to pull many extra pages of memory off the
disk: both the code for the static c'tors in each .o file and the small
amount of data that gets touched. In addition, touched/dirty pages put
more pressure on the VM system on low-memory machines.</li>
disk: both the code for the static c'tors in each <tt>.o</tt> file and the
small amount of data that gets touched. In addition, touched/dirty pages
put more pressure on the VM system on low-memory machines.</li>
</ol>
<div style="align: center">
<div align="center">
<table>
<tbody>
<tr>
@ -527,7 +527,7 @@ library. There are two problems with this:</p>
<td align="left"><pre>DEBUG(std::cerr &lt;&lt; ...);
DEBUG(dump(std::cerr));</pre></td>
<td align="left"><pre>DOUT &lt;&lt; ...;
dump(DOUT);</pre></td>
DEBUG(dump(DOUT));</pre></td>
</tr>
<tr>
<td align="left"><pre>std::cerr &lt;&lt; "Hello world\n";</pre></td>
@ -557,17 +557,17 @@ dump(DOUT);</pre></td>
<td align="left"><pre>void print(std::ostream &amp;Out);
// ...
print(std::cerr);</pre></td>
<td align="left"><pre>void print(std::ostream &amp;Out);
void print(std::ostream *Out) { if (Out) print(*Out) }
<td align="left"><pre>void print(llvm::OStream Out);<sup>1</sup>
// ...
print(llvm::cerr);</pre>
</td> </tbody> </table>
</div>
<div class="doc_text">
<i>N.B.</i> The second <tt>print</tt> method is called by the <tt>print</tt>
expression. It prevents the execution of the first <tt>print</tt> method if the
stream is <tt>cnull</tt>.</div></td>
</tbody>
</table>
<p><sup>1</sup><tt>llvm::OStream</tt> is a light-weight class so it should never
be passed by reference. This is important because in some configurations,
<tt>DOUT</tt> is an rvalue.</p>
</div>
</div>