<ol>
<li><a href="#scf_commenting">Commenting</a></li>
<li><a href="#scf_commentformat">Comment Formatting</a></li>
- <li><a href="#scf_includes">#include Style</a></li>
+ <li><a href="#scf_includes"><tt>#include</tt> Style</a></li>
<li><a href="#scf_codewidth">Source Code Width</a></li>
<li><a href="#scf_spacestabs">Use Spaces Instead of Tabs</a></li>
<li><a href="#scf_indentation">Indent Code Consistently</a></li>
<li><a href="#ci_warningerrors">Treat Compiler Warnings Like
Errors</a></li>
<li><a href="#ci_portable_code">Write Portable Code</a></li>
+ <li><a href="#ci_class_struct">Use of class/struct Keywords</a></li>
</ol></li>
</ol></li>
<li><a href="#styleissues">Style Issues</a>
<ol>
<li><a href="#hl_assert">Assert Liberally</a></li>
<li><a href="#hl_preincrement">Prefer Preincrement</a></li>
- <li><a href="#hl_avoidendl">Avoid std::endl</a></li>
+ <li><a href="#hl_avoidendl">Avoid <tt>std::endl</tt></a></li>
<li><a href="#hl_exploitcpp">Exploit C++ to its Fullest</a></li>
</ol></li>
</ol></li>
<div class="doc_text">
<p>Comments are one critical part of readability and maintainability. Everyone
-knows they should comment, so should you. :) Although we all should probably
+knows they should comment, so should you. Although we all should probably
comment our code more than we do, there are a few very critical places that
documentation is very useful:</p>
<p>A few things to note about this particular format: The "<tt>-*- C++
-*-</tt>" string on the first line is there to tell Emacs that the source file
-is a C++ file, not a C file (Emacs assumes .h files are C files by default [Note
-that tag this is not necessary in .cpp files]). The name of the file is also on
-the first line, along with a very short description of the purpose of the file.
-This is important when printing out code and flipping though lots of pages.</p>
+is a C++ file, not a C file (Emacs assumes .h files are C files by default).
+Note that this tag is not necessary in .cpp files. The name of the file is also
+on the first line, along with a very short description of the purpose of the
+file. This is important when printing out code and flipping though lots of
+pages.</p>
<p>The next section in the file is a concise note that defines the license that
the file is released under. This makes it perfectly clear what terms the source
a class definition should have a comment block that explains what the class is
used for... if it's not obvious. If it's so completely obvious your grandma
could figure it out, it's probably safe to leave it out. Naming classes
-something sane goes a long ways towards avoiding writing documentation. :)</p>
+something sane goes a long ways towards avoiding writing documentation.</p>
<b>Method information</b>
<ol>
<li>When writing a C code: Obviously if you are writing C code, use C style
- comments. :)</li>
- <li>When writing a header file that may be #included by a C source file.</li>
+ comments.</li>
+ <li>When writing a header file that may be <tt>#include</tt>d by a C source
+ file.</li>
<li>When writing a source file that is used by a tool that only accepts C
style comments.</li>
</ol>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
- <a name="scf_includes">#include Style</a>
+ <a name="scf_includes"><tt>#include</tt> Style</a>
</div>
<div class="doc_text">
<p>... and each catagory should be sorted by name.</p>
<p><a name="mmheader">The "Main Module Header"</a> file applies to .cpp file
-which implement an interface defined by a .h file. This #include should always
-be included <b>first</b> regardless of where it lives on the file system. By
-including a header file first in the .cpp files that implement the interfaces,
-we ensure that the header does not have any hidden dependencies which are not
-explicitly #included in the header, but should be. It is also a form of
-documentation in the .cpp file to indicate where the interfaces it implements
-are defined.</p>
+which implement an interface defined by a .h file. This <tt>#include</tt>
+should always be included <b>first</b> regardless of where it lives on the file
+system. By including a header file first in the .cpp files that implement the
+interfaces, we ensure that the header does not have any hidden dependencies
+which are not explicitly #included in the header, but should be. It is also a
+form of documentation in the .cpp file to indicate where the interfaces it
+implements are defined.</p>
</div>
</div>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+<a name="ci_class_struct">Use of <tt>class</tt> and <tt>struct</tt> Keywords</a>
+</div>
+<div class="doc_text">
+
+<p>In C++, the <tt>class</tt> and <tt>struct</tt> keywords can be used almost
+interchangeably. The only difference is when they are used to declare a class:
+<tt>class</tt> makes all members private by default while <tt>struct</tt> makes
+all members public by default.</p>
+
+<p>Unfortunately, not all compilers follow the rules and some will generate
+different symbols based on whether <tt>class</tt> or <tt>struct</tt> was used to
+declare the symbol. This can lead to problems at link time.</p>
+
+<p>So, the rule for LLVM is to always use the <tt>class</tt> keyword, unless
+<b>all</b> members are public, in which case <tt>struct</tt> is allowed.</p>
+
+</div>
+
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="styleissues">Style Issues</a>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
- <a name="hl_dontinclude">#include as Little as Possible</a>
+ <a name="hl_dontinclude"><tt>#include</tt> as Little as Possible</a>
</div>
<div class="doc_text">
have to, especially in header files.</p>
<p>But wait, sometimes you need to have the definition of a class to use it, or
-to inherit from it. In these cases go ahead and #include that header file. Be
-aware however that there are many cases where you don't need to have the full
-definition of a class. If you are using a pointer or reference to a class, you
-don't need the header file. If you are simply returning a class instance from a
-prototyped function or method, you don't need it. In fact, for most cases, you
-simply don't need the definition of a class... and not <tt>#include</tt>'ing
-speeds up compilation.</p>
+to inherit from it. In these cases go ahead and <tt>#include</tt> that header
+file. Be aware however that there are many cases where you don't need to have
+the full definition of a class. If you are using a pointer or reference to a
+class, you don't need the header file. If you are simply returning a class
+instance from a prototyped function or method, you don't need it. In fact, for
+most cases, you simply don't need the definition of a class... and not
+<tt>#include</tt>'ing speeds up compilation.</p>
<p>It is easy to try to go too overboard on this recommendation, however. You
<b>must</b> include all of the header files that you are using, either directly
<p>Many modules have a complex implementation that causes them to use more than
one implementation (<tt>.cpp</tt>) file. It is often tempting to put the
internal communication interface (helper classes, extra functions, etc) in the
-public module header file. Don't do this. :)</p>
+public module header file. Don't do this.</p>
<p>If you really need to do something like this, put a private header file in
the same directory as the source files, and include it locally. This ensures
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
- <a name="hl_avoidendl">Avoid std::endl</a>
+ <a name="hl_avoidendl">Avoid <tt>std::endl</tt></a>
</div>
<div class="doc_text">
good way to avoid documentation, and avoid giving bugs a place to hide.</p>
<p>For these reasons, come to know and love the contents of your local
-<algorithm> header file. Know about <functional> and what it can do
-for you. C++ is just a tool that wants you to master it. :)</p>
+<tt><algorithm></tt> header file. Know about <tt><functional></tt>
+and what it can do for you. C++ is just a tool that wants you to master it.</p>
</div>
</ol>
<p>If you get some free time, and you haven't read them: do so, you might learn
-something. :)</p>
+something.</p>
</div>
projects / oota-llvm.git / blobdiff