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<div class="titlepage">
<div><h1 class="title">
<a name="libstdc++-porting-howto"></a>Libstdc++-porting-howto</h1></div>
</td></tr>
</table></div></div>
<div><div class="abstract">
-<p>
-<a name="id2697062"></a><b>Abstract</b>
-</p>
+<p><b>Abstract</b></p>
<p>
Some notes on porting applications from libstdc++-2.90 (or earlier
versions) to libstdc++-v3. Not speaking in terms of the GNU libstdc++
<dt>1. <a href="#sec-nsstd">Namespace std::</a>
</dt>
<dd><dl>
-<dt>1.1.1. <a href="#sec-gtkmm-hack">Using <i>namespace
- composition</i> if the project uses a separate
+<dt>1.1.1. <a href="#sec-gtkmm-hack">Using namespace
+ composition if the project uses a separate
namespace</a>
</dt>
<dt>1.1.2. <a href="#sec-emptyns">Defining an empty namespace std</a>
<dt>2. <a href="#sec-nocreate">there is no ios::nocreate/ios::noreplace
in ISO 14882</a>
</dt>
-<dt>3. <a href="#sec-stream::attach"><b>stream::attach(int
- fd)</b> is not in the standard any more</a>
+<dt>3. <a href="#sec-stream::attach">stream::attach(int
+ fd) is not in the standard any more</a>
</dt>
<dt>4. <a href="#sec-headers">The new headers</a>
</dt>
<dt>4.4.1. <a href="#sec-cheaders">New headers replacing C-headers</a>
</dt>
<dt>4.4.2. <a href="#sec-fstream-header">
- <tt><fstream></tt> does
- not define <b>std::cout</b>,
- <b>std::cin</b> etc.</a>
+ <fstream> does
+ not define std::cout,
+ std::cin etc.</a>
</dt>
</dl></dd>
<dt>5. <a href="#sec-iterators">Iterators</a>
</dt>
<dt>6. <a href="#sec-macros">
- Libc-macros (i.e. <b>isspace</b> from
- <tt><cctype></tt>)</a>
+ Libc-macros (i.e. isspace from
+ <cctype>)</a>
</dt>
<dt>7. <a href="#sec-stream-state">State of streams</a>
</dt>
libstdc++-implementations".
</p>
<div class="section">
-<a name="sec-nsstd"></a><div class="titlepage"><div><h2 class="title" style="clear: all">
-<a name="sec-nsstd"></a><span class="label">1.</span> <span class="title">Namespace std::</span>
-</h2></div></div>
+<div class="titlepage"><div><h2 class="title" style="clear: both">
+<a name="sec-nsstd"></a>Namespace std::</h2></div></div>
<p>
The latest C++-standard (ISO-14882) requires that the standard
C++-library is defined in namespace std::. Thus, in order to use
classes from the standard C++-library, you can do one of three
things:
- <div class="itemizedlist"><ul>
-<li><p>
-<a name="id2697113"></a>wrap your code in <b>namespace std {
+ <div class="itemizedlist"><ul type="disc">
+<li><p>wrap your code in <b>namespace std {
... }</b> => This is not an option because only symbols
from the standard c++-library are defined in namespace std::.
</p></li>
-<li><p>
-<a name="id2697126"></a>put a kind of
- <i>using-declaration</i> in your source (either
+<li><p>put a kind of
+ <span class="emphasis"><i>using-declaration</i></span> in your source (either
<b>using namespace std;</b> or i.e. <b>using
std::string;</b>) => works well for source-files, but
cannot be used in header-files.
</p></li>
-<li><p>
-<a name="id2697047"></a>use a <i>fully qualified name</i> for
+<li><p>use a <span class="emphasis"><i>fully qualified name</i></span> for
each libstdc++-symbol (i.e. <b>std::string</b>,
<b>std::cout</b>) => can always be used
</p></li>
that cannot ignore std::.
</p>
<div class="section">
-<a name="sec-gtkmm-hack"></a><div class="titlepage"><div><h3 class="title">
-<a name="sec-gtkmm-hack"></a><span class="label">1.1.1.</span> <span class="title">Using <i>namespace
- composition</i> if the project uses a separate
- namespace</span>
-</h3></div></div>
+<div class="titlepage"><div><h3 class="title">
+<a name="sec-gtkmm-hack"></a>Using <span class="emphasis"><i>namespace
+ composition</i></span> if the project uses a separate
+ namespace</h3></div></div>
<p>
<a href="http://gtkmm.sourceforge.net" target="_top">Gtk--</a> defines
most of its classes in namespace Gtk::. Thus, it was possible to
adapt Gtk-- to namespace std:: by using a C++-feature called
- <i>namespace composition</i>. This is what happens if
- you put a <i>using</i>-declaration into a
+ <span class="emphasis"><i>namespace composition</i></span>. This is what happens if
+ you put a <span class="emphasis"><i>using</i></span>-declaration into a
namespace-definition: the imported symbol(s) gets imported into the
currently active namespace(s). For example:
<pre class="programlisting">
</p>
</div>
<div class="section">
-<a name="sec-emptyns"></a><div class="titlepage"><div><h3 class="title">
-<a name="sec-emptyns"></a><span class="label">1.1.2.</span> <span class="title">Defining an empty namespace std</span>
-</h3></div></div>
+<div class="titlepage"><div><h3 class="title">
+<a name="sec-emptyns"></a>Defining an empty namespace std</h3></div></div>
<p>
By defining an (empty) namespace <b>std::</b> before
using it, you avoid getting errors on systems where no part of the
</p>
</div>
<div class="section">
-<a name="sec-avoidfqn"></a><div class="titlepage"><div><h3 class="title">
-<a name="sec-avoidfqn"></a><span class="label">1.1.3.</span> <span class="title">Avoid to use fully qualified names
- (i.e. std::string)</span>
-</h3></div></div>
+<div class="titlepage"><div><h3 class="title">
+<a name="sec-avoidfqn"></a>Avoid to use fully qualified names
+ (i.e. std::string)</h3></div></div>
<p>
If some compilers complain about <b>using
std::string;</b>, and if the "hack" for gtk-- mentioned above
does not work, then I see two solutions:
- <div class="itemizedlist"><ul>
+ <div class="itemizedlist"><ul type="disc">
<li><p>
-<a name="id2698648"></a>
Define <b>std::</b> as a macro if the compiler
doesn't know about <b>std::</b>.
<pre class="programlisting">
gnu.gcc.help)
</p></li>
<li><p>
-<a name="id2698680"></a>
Define a macro NS_STD, which is defined to
either "" or "std"
based on an autoconf-test. Then you should be able to use
</p>
</div>
<div class="section">
-<a name="sec-osprojects"></a><div class="titlepage"><div><h3 class="title">
-<a name="sec-osprojects"></a><span class="label">1.1.4.</span> <span class="title">How some open-source-projects deal
- with this</span>
-</h3></div></div>
+<div class="titlepage"><div><h3 class="title">
+<a name="sec-osprojects"></a>How some open-source-projects deal
+ with this</h3></div></div>
<p>
This information was gathered around May 2000. It may not be correct
by the time you read this.
</p>
<div class="table">
-<p>
-<a name="id2698746"></a><b>Table 1. Namespace std:: in Open-Source programs</b>
-</p>
+<p><b>Table 1. Namespace std:: in Open-Source programs</b></p>
<table summary="Namespace std:: in Open-Source programs" border="1">
<colgroup>
<col>
</table>
</div>
<div class="table">
-<p>
-<a name="id2698876"></a><b>Table 2. Notations for categories</b>
-</p>
+<p><b>Table 2. Notations for categories</b></p>
<table summary="Notations for categories" border="1">
<colgroup>
<col>
<p>
As you can see, this currently lacks an example of a project
which uses libstdc++-symbols in headers in a back-portable way
- (except for Gtk--: see the <a href="#sec-gtkmm-hack">section on the gtkmm-hack</a>).
+ (except for Gtk--: see the <a href="#sec-gtkmm-hack" title="Using namespace
+ composition if the project uses a separate
+ namespace">section on the gtkmm-hack</a>).
</p>
</div>
</div>
<div class="section">
-<a name="sec-nocreate"></a><div class="titlepage"><div><h2 class="title" style="clear: all">
-<a name="sec-nocreate"></a><span class="label">2.</span> <span class="title">there is no ios::nocreate/ios::noreplace
- in ISO 14882</span>
-</h2></div></div>
+<div class="titlepage"><div><h2 class="title" style="clear: both">
+<a name="sec-nocreate"></a>there is no ios::nocreate/ios::noreplace
+ in ISO 14882</h2></div></div>
<p>
I have seen <b>ios::nocreate</b> being used for
input-streams, most probably because the author thought it would be
</p>
</div>
<div class="section">
-<a name="sec-stream::attach"></a><div class="titlepage"><div><h2 class="title" style="clear: all">
-<a name="sec-stream::attach"></a><span class="label">3.</span> <span class="title"><b>stream::attach(int
- fd)</b> is not in the standard any more</span>
-</h2></div></div>
+<div class="titlepage"><div><h2 class="title" style="clear: both">
+<a name="sec-stream::attach"></a><b>stream::attach(int
+ fd)</b> is not in the standard any more</h2></div></div>
<p>
Phil Edwards <tt><<a href="mailto:pedwards@disaster.jaj.com">pedwards@disaster.jaj.com</a>></tt> writes:
It was considered and rejected. Not all environments use file
</p>
<p>
When using libstdc++-v3, you can use
- <div class="funcsynopsis" id="id2692860">
-<p>
-<a name="id2692860"></a><pre class="funcsynopsisinfo">
+ <div class="funcsynopsis">
+<pre class="funcsynopsisinfo">
#include <fstream>
</pre>
<p><code><code class="funcdef">
<b class="fsfunc">basic_filebuf<...>::basic_filebuf<...>
</b>
</code>(<var class="pdparam">file</var>, <var class="pdparam">mode</var>, <var class="pdparam">size</var>);<br>__c_file_type* <var class="pdparam">file</var>;<br>ios_base::open_mode <var class="pdparam">mode</var>;<br>int <var class="pdparam">size</var>;</code></p>
-<p>
</div>
but the the signature of this constructor has changed often, and
it might change again. For the current state of this, check
<b>std::streambuf</b> (or
<b>std::basic_streambuf<..></b>) which opens a file
given a descriptor, and then pass an instance of this to the
- stream-constructor (from the Josuttis-book).
+ stream-constructor. For an example of this, refer to
+ <a href="http://www.josuttis.com/cppcode/fdstream.html" target="_top">fdstream example</a>
+ by Nicolai Josuttis.
</p>
</div>
<div class="section">
-<a name="sec-headers"></a><div class="titlepage"><div><h2 class="title" style="clear: all">
-<a name="sec-headers"></a><span class="label">4.</span> <span class="title">The new headers</span>
-</h2></div></div>
+<div class="titlepage"><div><h2 class="title" style="clear: both">
+<a name="sec-headers"></a>The new headers</h2></div></div>
<p>
All new headers can be seen in this <a href="headers_cc.txt" target="_top">
source-code</a>.
a warning that you are using deprecated headers.
</p>
<div class="section">
-<a name="sec-cheaders"></a><div class="titlepage"><div><h3 class="title">
-<a name="sec-cheaders"></a><span class="label">4.4.1.</span> <span class="title">New headers replacing C-headers</span>
-</h3></div></div>
+<div class="titlepage"><div><h3 class="title">
+<a name="sec-cheaders"></a>New headers replacing C-headers</h3></div></div>
<p>
You should not use the C-headers (except for system-level
headers) from C++ programs. Instead, you should use a set of
</p>
</div>
<div class="section">
-<
a name="sec-fstream-header"></a><div class="titlepage"><div><h3 class="title">
-<a name="sec-fstream-header"></a><span class="label">4.4.2.</span> <span class="title">
+<div class="titlepage"><div><h3 class="title">
+<a name="sec-fstream-header"></a>
<tt><fstream></tt> does
not define <b>std::cout</b>,
- <b>std::cin</b> etc.</span>
-</h3></div></div>
+ <b>std::cin</b> etc.</h3></div></div>
<p>
In earlier versions of the standard,
<tt><fstream.h></tt>,
</div>
</div>
<div class="section">
-<a name="sec-iterators"></a><div class="titlepage"><div><h2 class="title" style="clear: all">
-<a name="sec-iterators"></a><span class="label">5.</span> <span class="title">Iterators</span>
-</h2></div></div>
+<div class="titlepage"><div><h2 class="title" style="clear: both">
+<a name="sec-iterators"></a>Iterators</h2></div></div>
<p>
The following are not proper uses of iterators, but may be working
fixes for existing uses of iterators.
- <div class="itemizedlist"><ul>
-<li><p>
-<a name="id2693156"></a>you cannot do
+ <div class="itemizedlist"><ul type="disc">
+<li><p>you cannot do
<b>ostream::operator<<(iterator)</b> to
print the address of the iterator => use
<b>operator<< &*iterator</b> instead ?
</p></li>
-<li><p>
-<a name="id2693255"></a>you cannot clear an iterator's reference
+<li><p>you cannot clear an iterator's reference
(<b>iterator = 0</b>) => use
<b>iterator = iterator_type();</b> ?
</p></li>
<li><p>
-<a name="id2693277"></a><b>if (iterator)</b> won't work any
+<b>if (iterator)</b> won't work any
more => use <b>if (iterator != iterator_type())</b>
?</p></li>
</ul></div>
</p>
</div>
<div class="section">
-<a name="sec-macros"></a><div class="titlepage"><div><h2 class="title" style="clear: all">
-<a name="sec-macros"></a><span class="label">6.</span> <span class="title">
+<div class="titlepage"><div><h2 class="title" style="clear: both">
+<a name="sec-macros"></a>
Libc-macros (i.e. <b>isspace</b> from
- <tt><cctype></tt>)</span>
-</h2></div></div>
+ <tt><cctype></tt>)</h2></div></div>
<p>
Glibc 2.0.x and 2.1.x define the
<tt><ctype.h></tt>
-functionality as macros (isspace, isalpha etc.). Libstdc++-v3
- "shadows" these macros as described in the <a href="#sec-cheaders">section about
+ "shadows" these macros as described in the <a href="#sec-cheaders" title="New headers replacing C-headers">section about
c-headers</a>.
</p>
<p>
The solution to this problem was posted to the libstdc++-v3
mailing-list:
Benjamin Kosnik <tt><<a href="mailto:bkoz@redhat.com">bkoz@redhat.com</a>></tt> writes:
- `
+ ‘
--enable-cshadow-headers is currently broken. As a result, shadow
headers are not being searched....
- '
+ ’
This is now outdated, but gcc 3.0 still does not have fully
compliant "shadow headers".
</p>
</div>
<div class="section">
-<a name="sec-stream-state"></a><div class="titlepage"><div><h2 class="title" style="clear: all">
-<a name="sec-stream-state"></a><span class="label">7.</span> <span class="title">State of streams</span>
-</h2></div></div>
+<div class="titlepage"><div><h2 class="title" style="clear: both">
+<a name="sec-stream-state"></a>State of streams</h2></div></div>
<p>
At least some older implementations don't have
<b>std::ios_base</b>, so you should use
</p>
</div>
<div class="section">
-<a name="sec-vector-at"></a><div class="titlepage"><div><h2 class="title" style="clear: all">
-<a name="sec-vector-at"></a><span class="label">8.</span> <span class="title">vector::at is missing (i.e. gcc 2.95.x)</span>
-</h2></div></div>
+<div class="titlepage"><div><h2 class="title" style="clear: both">
+<a name="sec-vector-at"></a>vector::at is missing (i.e. gcc 2.95.x)</h2></div></div>
<p>
One solution is to add an autoconf-test for this:
<pre class="programlisting">
</p>
</div>
<div class="section">
-<a name="sec-eof"></a><div class="titlepage"><div><h2 class="title" style="clear: all">
-<a name="sec-eof"></a><span class="label">9.</span> <span class="title">Using std::char_traits<char>::eof()</span>
-</h2></div></div>
+<div class="titlepage"><div><h2 class="title" style="clear: both">
+<a name="sec-eof"></a>Using std::char_traits<char>::eof()</h2></div></div>
<p>
<pre class="programlisting">
#ifdef HAVE_CHAR_TRAITS
</p>
</div>
<div class="section">
-<a name="sec-string-clear"></a><div class="titlepage"><div><h2 class="title" style="clear: all">
-<a name="sec-string-clear"></a><span class="label">10.</span> <span class="title">Using string::clear()/string::erase()</span>
-</h2></div></div>
+<div class="titlepage"><div><h2 class="title" style="clear: both">
+<a name="sec-string-clear"></a>Using string::clear()/string::erase()</h2></div></div>
<p>
There are two functions for deleting the contents of a string:
<b>clear</b> and <b>erase</b> (the latter
</p>
</div>
<div class="section">
-<a name="sec-scan-form"></a><div class="titlepage"><div><h2 class="title" style="clear: all">
-<a name="sec-scan-form"></a><span class="label">11.</span> <span class="title">GNU Extensions ostream::form and istream::scan</span>
-</h2></div></div>
+<div class="titlepage"><div><h2 class="title" style="clear: both">
+<a name="sec-scan-form"></a>GNU Extensions ostream::form and istream::scan</h2></div></div>
<p>
These are not supported any more - use
- <a href="#sec-stringstream">
+ <a href="#sec-stringstream" title="Using stringstreams">
stringstreams</a> instead.
</p>
</div>
<div class="section">
-<a name="sec-stringstream"></a><div class="titlepage"><div><h2 class="title" style="clear: all">
-<a name="sec-stringstream"></a><span class="label">12.</span> <span class="title">Using stringstreams</span>
-</h2></div></div>
+<div class="titlepage"><div><h2 class="title" style="clear: both">
+<a name="sec-stringstream"></a>Using stringstreams</h2></div></div>
<p>
Libstdc++-v3 provides the new
<b>i/ostringstream</b>-classes, (<tt><sstream></tt>), but for compatibility
#include <strstream>
#endif
</pre>
- <div class="itemizedlist"><ul>
-<li><p>
-<a name="id2693683"></a> <b>strstream</b> is considered to be
+ <div class="itemizedlist"><ul type="disc">
+<li><p> <b>strstream</b> is considered to be
deprecated
</p></li>
-<li><p>
-<a name="id2693629"></a> <b>strstream</b> is limited to
+<li><p> <b>strstream</b> is limited to
<b>char</b>
</p></li>
-<li><p>
-<a name="id2693718"></a> with <b>ostringstream</b> you don't
+<li><p> with <b>ostringstream</b> you don't
have to take care of terminating the string or freeing its
memory
</p></li>
-<li><p>
-<a name="id2693735"></a> <b>istringstream</b> can be re-filled
+<li><p> <b>istringstream</b> can be re-filled
(clear(); str(input);)
</p></li>
</ul></div>
</p>
</div>
<div class="section">
-<a name="sec-about"></a><div class="titlepage"><div><h2 class="title" style="clear: all">
-<a name="sec-about"></a><span class="label">13.</span> <span class="title">About...</span>
-</h2></div></div>
+<div class="titlepage"><div><h2 class="title" style="clear: both">
+<a name="sec-about"></a>About...</h2></div></div>
<p>
Please send any experience, additions, corrections or questions to
<a href="mailto:fnatter@gmx.net" target="_top">fnatter@gmx.net</a> or for
projects / gcc.git / commitdiff