dced0d12fb
2003-07-16 Jonathan Wakely <redi@gcc.gnu.org> * docs/html/ext/howto.html: Update URL for SGI STL docs. * docs/html/faq/index.html: Same. * docs/html/faq/index.txt: Regenerate. From-SVN: r69463
668 lines
28 KiB
HTML
668 lines
28 KiB
HTML
<?xml version="1.0" encoding="ISO-8859-1"?>
|
|
<!DOCTYPE html
|
|
PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
|
|
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
|
|
|
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
|
|
<head>
|
|
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
|
|
<meta name="AUTHOR" content="pme@gcc.gnu.org (Phil Edwards)" />
|
|
<meta name="KEYWORDS" content="HOWTO, libstdc++, GCC, g++, libg++, STL" />
|
|
<meta name="DESCRIPTION" content="Notes for the libstdc++ extensions." />
|
|
<meta name="GENERATOR" content="vi and eight fingers" />
|
|
<title>libstdc++-v3 HOWTO: Extensions</title>
|
|
<link rel="StyleSheet" href="../lib3styles.css" />
|
|
</head>
|
|
<body>
|
|
|
|
<h1 class="centered"><a name="top">Extensions</a></h1>
|
|
|
|
<p>Here we will make an attempt at describing the non-Standard extensions to
|
|
the library. Some of these are from SGI's STL, some of these are GNU's,
|
|
and some just seemed to appear on the doorstep.
|
|
</p>
|
|
<p><strong>Before you leap in and use these</strong>, be aware of two things:
|
|
</p>
|
|
<ol>
|
|
<li>Non-Standard means exactly that. The behavior, and the very
|
|
existence, of these extensions may change with little or no
|
|
warning. (Ideally, the really good ones will appear in the next
|
|
revision of C++.) Also, other platforms, other compilers, other
|
|
versions of g++ or libstdc++-v3 may not recognize these names, or
|
|
treat them differently, or... </li>
|
|
<li>You should know how to <a href="../faq/index.html#5_4">access
|
|
these headers properly</a>. </li>
|
|
</ol>
|
|
|
|
|
|
<!-- ####################################################### -->
|
|
<hr />
|
|
<h1>Contents</h1>
|
|
<ul>
|
|
<li><a href="#1">Ropes and trees and hashes, oh my!</a></li>
|
|
<li><a href="#2">Added members and types</a></li>
|
|
<li><a href="#3">Allocators (versions 3.0, 3.1, 3.2, 3.3)</a></li>
|
|
<li><a href="#6">Allocators (version 3.4)</a></li>
|
|
<li><a href="#4">Compile-time checks</a></li>
|
|
<li><a href="#5">LWG Issues</a></li>
|
|
<li><a href="../18_support/howto.html#5">Demangling</a></li>
|
|
</ul>
|
|
|
|
<hr />
|
|
|
|
<!-- ####################################################### -->
|
|
|
|
<h2><a name="1">Ropes and trees and hashes, oh my!</a></h2>
|
|
<p>The SGI headers</p>
|
|
<pre>
|
|
<bvector>
|
|
<hash_map>
|
|
<hash_set>
|
|
<rope>
|
|
<slist>
|
|
<tree>
|
|
</pre>
|
|
<p>are all here; <code><bvector></code> exposes the old bit_vector
|
|
class that was used before specialization of vector<bool> was
|
|
available (it's actually a typedef for the specialization now).
|
|
<code><hash_map></code> and <code><hash_set></code>
|
|
are discussed further below. <code><rope></code> is the SGI
|
|
specialization for large strings ("rope," "large
|
|
strings," get it? love those SGI folks).
|
|
<code><slist></code> is a singly-linked list, for when the
|
|
doubly-linked <code>list<></code> is too much space overhead, and
|
|
<code><tree></code> exposes the red-black tree classes used in the
|
|
implementation of the standard maps and sets.
|
|
</p>
|
|
<p>Okay, about those hashing classes... I'm going to foist most of the
|
|
work off onto SGI's own site.
|
|
</p>
|
|
<p>Each of the associative containers map, multimap, set, and multiset
|
|
have a counterpart which uses a
|
|
<a href="http://www.sgi.com/tech/stl/HashFunction.html">hashing
|
|
function</a> to do the arranging, instead of a strict weak ordering
|
|
function. The classes take as one of their template parameters a
|
|
function object that will return the hash value; by default, an
|
|
instantiation of
|
|
<a href="http://www.sgi.com/tech/stl/hash.html">hash</a>.
|
|
You should specialize this functor for your class, or define your own,
|
|
before trying to use one of the hashing classes.
|
|
</p>
|
|
<p>The hashing classes support all the usual associative container
|
|
functions, as well as some extra constructors specifying the number
|
|
of buckets, etc.
|
|
</p>
|
|
<p>Why would you want to use a hashing class instead of the
|
|
"normal" implementations? Matt Austern writes:
|
|
</p>
|
|
<blockquote><em>[W]ith a well chosen hash function, hash tables
|
|
generally provide much better average-case performance than binary
|
|
search trees, and much worse worst-case performance. So if your
|
|
implementation has hash_map, if you don't mind using nonstandard
|
|
components, and if you aren't scared about the possibility of
|
|
pathological cases, you'll probably get better performance from
|
|
hash_map.</em></blockquote>
|
|
<p>(Side note: for those of you wondering, <strong>"Why wasn't a hash
|
|
table included in the Standard in the first #!$@ place?"</strong>
|
|
I'll give a quick answer: it was proposed, but too late and in too
|
|
unorganized a fashion. Some sort of hashing will undoubtedly be
|
|
included in a future Standard.)
|
|
</p>
|
|
<p>Return <a href="#top">to top of page</a> or
|
|
<a href="../faq/index.html">to the FAQ</a>.
|
|
</p>
|
|
|
|
<hr />
|
|
<h2><a name="2">Added members and types</a></h2>
|
|
<p>Some of the classes in the Standard Library have additional
|
|
publicly-available members, and some classes are themselves not in
|
|
the standard. Of those, some are intended purely for the implementors,
|
|
for example, additional typedefs. Those won't be described here
|
|
(or anywhere else).
|
|
</p>
|
|
<ul>
|
|
<li>The extensions added by SGI are so numerous that they have
|
|
<a href="sgiexts.html">their own page</a>. Since the SGI STL is no
|
|
longer actively maintained, we will try and keep this code working
|
|
ourselves.</li>
|
|
<li>Extensions allowing <code>filebuf</code>s to be constructed from
|
|
stdio types are described in the
|
|
<a href="../27_io/howto.html#11">chapter 27 notes</a>.</li>
|
|
</ul>
|
|
<p>Return <a href="#top">to top of page</a> or
|
|
<a href="../faq/index.html">to the FAQ</a>.
|
|
</p>
|
|
|
|
<hr />
|
|
<h2><a name="3">Allocators (versions 3.0, 3.1, 3.2, 3.3)</a></h2>
|
|
<p>Thread-safety, space efficiency, high speed, portability... this is a
|
|
mess. Where to begin?
|
|
</p>
|
|
<h3>The Rules</h3>
|
|
<p>The C++ standard only gives a few directives in this area:
|
|
</p>
|
|
<ul>
|
|
<li>When you add elements to a container, and the container must allocate
|
|
more memory to hold them, the container makes the request via its
|
|
<code>Allocator</code> template parameter. This includes adding
|
|
char's to the string class, which acts as a regular STL container
|
|
in this respect.
|
|
</li>
|
|
<li>The default <code>Allocator</code> of every container-of-T is
|
|
<code>std::allocator<T></code>.
|
|
</li>
|
|
<li>The interface of the <code>allocator<T></code> class is
|
|
extremely simple. It has about 20 public declarations (nested
|
|
typedefs, member functions, etc), but the two which concern us most
|
|
are:
|
|
<pre>
|
|
T* allocate (size_type n, const void* hint = 0);
|
|
void deallocate (T* p, size_type n);</pre>
|
|
(This is a simplicifcation; the real signatures use nested typedefs.)
|
|
The <code>"n"</code> arguments in both those functions is a
|
|
<em>count</em> of the number of T's to allocate space for,
|
|
<em>not their total size</em>.
|
|
</li>
|
|
<li>"The storage is obtained by calling
|
|
<code>::operator new(size_t)</code>, but it is unspecified when or
|
|
how often this function is called. The use of <code>hint</code>
|
|
is unspecified, but intended as an aid to locality if an
|
|
implementation so desires." [20.4.1.1]/6
|
|
</li>
|
|
</ul>
|
|
<h3>Problems and Possibilities</h3>
|
|
<p>The easiest way of fulfilling the requirements is to call operator new
|
|
each time a container needs memory, and to call operator delete each
|
|
time the container releases memory. <strong>BUT</strong>
|
|
<a href="http://gcc.gnu.org/ml/libstdc++/2001-05/msg00105.html">this
|
|
method is horribly slow</a>.
|
|
</p>
|
|
<p>Or we can keep old memory around, and reuse it in a pool to save time.
|
|
The old libstdc++-v2 used a memory pool, and so do we. As of 3.0,
|
|
<a href="http://gcc.gnu.org/ml/libstdc++/2001-05/msg00136.html">it's
|
|
on by default</a>. The pool is shared among all the containers in the
|
|
program: when your program's std::vector<int> gets cut in half
|
|
and frees a bunch of its storage, that memory can be reused by the
|
|
private std::list<WonkyWidget> brought in from a KDE library
|
|
that you linked against. And we don't have to call operators new and
|
|
delete to pass the memory on, either, which is a speed bonus.
|
|
<strong>BUT</strong>...
|
|
</p>
|
|
<p>What about threads? No problem: in a threadsafe environment, the
|
|
memory pool is manipulated atomically, so you can grow a container in
|
|
one thread and shrink it in another, etc. <strong>BUT</strong> what
|
|
if threads in libstdc++-v3 aren't set up properly?
|
|
<a href="../faq/index.html#5_6">That's been answered already</a>.
|
|
</p>
|
|
<p><strong>BUT</strong> what if you want to use your own allocator? What
|
|
if you plan on using a runtime-loadable version of malloc() which uses
|
|
shared telepathic anonymous mmap'd sections serializable over a
|
|
network, so that memory requests <em>should</em> go through malloc?
|
|
And what if you need to debug it?
|
|
</p>
|
|
<p>Well then:
|
|
</p>
|
|
<h3>Available allocators in namespace std</h3>
|
|
<p>First I'll describe the situation as it exists for the code which
|
|
was released in GCC 3.1 and 3.2. Then I'll describe the differences
|
|
for 3.0. The allocator classes also have source documentation,
|
|
which is described <a href="../documentation.html#4">here</a> (you
|
|
will need to retrieve the maintainer-level docs, as almost none of
|
|
these entities are in the ISO standard).
|
|
</p>
|
|
<p>As a general rule of thumb, users are not allowed to use names which
|
|
begin with an underscore. This means that to be portable between
|
|
compilers, none of the following may be used in your program directly.
|
|
(If you decide to be unportable, then you're free do do what you want,
|
|
but it's not our fault if stuff breaks.) They are presented here for
|
|
information for maintainers and contributors in addition to users.
|
|
</p>
|
|
<p>These classes are always available:
|
|
</p>
|
|
<ul>
|
|
<li><code>__new_alloc</code> simply wraps <code>::operator new</code>
|
|
and <code>::operator delete</code>.
|
|
</li>
|
|
<li><code>__malloc_alloc_template<int inst></code> simply wraps
|
|
<code>malloc</code> and <code>free</code>. There is also a hook
|
|
for an out-of-memory handler (for new/delete this is taken care of
|
|
elsewhere). The <code>inst</code> parameter is described below.
|
|
This class was called <code>malloc_alloc</code> in earlier versions.
|
|
</li>
|
|
<li><code>allocator<T></code> has already been described; it is
|
|
The Standard Allocator for instances of T. It uses the internal
|
|
<code>__alloc</code> typedef (see below) to satisy its requests.
|
|
</li>
|
|
<li><code>__simple_alloc<T,A></code> is a wrapper around another
|
|
allocator, A, which itself is an allocator for instances of T.
|
|
This is primarily used in an internal "allocator traits"
|
|
class which helps encapsulate the different styles of allocators.
|
|
</li>
|
|
<li><code>__debug_alloc<A></code> is also a wrapper around an
|
|
arbitrary allocator A. It passes on slightly increased size
|
|
requests to A, and uses the extra memory to store size information.
|
|
When a pointer is passed to <code>deallocate()</code>, the stored
|
|
size is checked, and assert() is used to guarantee they match.
|
|
</li>
|
|
<li><code>__allocator<T,A></code> is an adaptor. Many of these
|
|
allocator classes have a consistent yet non-standard interface.
|
|
Such classes can be changed to a conforming interface with this
|
|
wrapper: <code>__allocator<T, __alloc></code> is thus the
|
|
same as <code>allocator<T></code>.
|
|
</li>
|
|
</ul>
|
|
<p>Normally,
|
|
<code> __default_alloc_template<bool thr, int inst> </code>
|
|
is also available. This is the high-speed pool, called the default
|
|
node allocator. The reusable memory is shared among identical
|
|
instantiations of
|
|
this type. It calls through <code>__new_alloc</code> to obtain
|
|
new memory when its lists run out. If a client container requests a
|
|
block larger than a certain threshold size, then the pool is bypassed,
|
|
and the allocate/deallocate request is passed to
|
|
<code>__new_alloc</code> directly.
|
|
</p>
|
|
<p>Its <code>inst</code> parameter is described below. The
|
|
<code>thr</code> boolean determines whether the pool should be
|
|
manipulated atomically or not. Two typedefs are provided:
|
|
<code>__alloc</code> is defined as this node allocator with thr=true,
|
|
and therefore is threadsafe, while <code>__single_client_alloc</code>
|
|
defines thr=false, and is slightly faster but unsafe for multiple
|
|
threads.
|
|
</p>
|
|
<p>(Note that the GCC thread abstraction layer allows us to provide safe
|
|
zero-overhead stubs for the threading routines, if threads were
|
|
disabled at configuration time. In this situation,
|
|
<code>__alloc</code> should not be noticably slower than
|
|
<code>__single_client_alloc</code>.)
|
|
</p>
|
|
<p>[Another threadsafe allocator where each thread keeps its own free
|
|
list, so that no locking is needed, might be described here.]
|
|
</p>
|
|
<h3>A cannon to swat a fly:<code> __USE_MALLOC</code></h3>
|
|
<p>If you've already read <a href="../23_containers/howto.html#3">this
|
|
advice</a> but still think you remember how to use this macro from
|
|
SGI STL days. We have removed it in gcc 3.3. See next section
|
|
for the new way to get the same effect.
|
|
</p>
|
|
<h3>Globally disabling memory caching:<code> GLIBCPP_FORCE_NEW</code></h3>
|
|
<p>Starting with gcc 3.3, if you want to globally disable memory
|
|
caching within the library for the default allocator (i.e.
|
|
the one you get for all library objects when you do not specify
|
|
which one to use), merely set GLIBCPP_FORCE_NEW (at this time,
|
|
with any value) into your environment before running the
|
|
program. You will obtain a similar effect without having to
|
|
recompile your entire program and the entire library (the new
|
|
operator in gcc is a light wrapper around malloc). If your
|
|
program crashes with GLIBCPP_FORCE_NEW in the environment,
|
|
it likely means that you linked against objects built against
|
|
the older library. Code to support this extension is fully
|
|
compatible with 3.2 code if GLIBCPP_FORCE_NEW is not in the
|
|
environment.
|
|
</p>
|
|
<h3>Writing your own allocators</h3>
|
|
<p>Depending on your application (a specific program, a generic library,
|
|
etc), allocator classes tend to be one of two styles: "SGI"
|
|
or "standard". See the comments in stl_alloc.h for more
|
|
information on this crucial difference.
|
|
</p>
|
|
<p>At the bottom of that header is a helper type,
|
|
<code>_Alloc_traits</code>, and various specializations of it. This
|
|
allows the container classes to make possible compile-time
|
|
optimizations based on features of the allocator. You should provide
|
|
a specialization of this type for your allocator (doing so takes only
|
|
two or three statements).
|
|
</p>
|
|
<h3>Using non-default allocators</h3>
|
|
<p>You can specify different memory management schemes on a per-container
|
|
basis, by overriding the default <code>Allocator</code> template
|
|
parameter. For example, an easy
|
|
(but nonportable)
|
|
method of specifying that only malloc/free should be used instead of
|
|
the default node allocator is:
|
|
</p>
|
|
<pre>
|
|
std::list <my_type, std::__malloc_alloc_template<0> > my_malloc_based_list;</pre>
|
|
Likewise, a debugging form of whichever allocator is currently in use:
|
|
<pre>
|
|
std::deque <my_type, std::__debug_alloc<std::__alloc> > debug_deque;</pre>
|
|
<h3><code>inst</code></h3>
|
|
<p>The <code>__malloc_alloc_template</code> and
|
|
<code>__default_alloc_template</code> classes take an integer parameter,
|
|
called inst here. This number is completely unused.
|
|
</p>
|
|
<p>The point of the number is to allow multiple instantiations of the
|
|
classes without changing the semantics at all. All three of
|
|
</p>
|
|
<pre>
|
|
typedef __default_alloc_template<true,0> normal;
|
|
typedef __default_alloc_template<true,1> private;
|
|
typedef __default_alloc_template<true,42> also_private;</pre>
|
|
<p>behave exactly the same way. However, the memory pool for each type
|
|
(and remember that different instantiations result in different types)
|
|
remains separate.
|
|
</p>
|
|
<p>The library uses <strong>0</strong> in all its instantiations. If you
|
|
wish to keep separate free lists for a particular purpose, use a
|
|
different number.
|
|
</p>
|
|
<h3>3.0.x</h3>
|
|
<p>For 3.0.x, many of the names were incorrectly <em>not</em> prefixed
|
|
with underscores. So symbols such as "std::single_client_alloc"
|
|
are present. Be very careful to not depend on these names any more
|
|
than you would depend on implementation-only names.
|
|
</p>
|
|
<p>Certain macros like <code>_NOTHREADS</code> and <code>__STL_THREADS</code>
|
|
can affect the 3.0.x allocators. Do not use them. Those macros have
|
|
been completely removed for 3.1.
|
|
</p>
|
|
<p>Return <a href="#top">to top of page</a> or
|
|
<a href="../faq/index.html">to the FAQ</a>.
|
|
</p>
|
|
|
|
<hr />
|
|
<h2><a name="6">Allocators (version 3.4)</a></h2>
|
|
<p>Changes are coming...
|
|
</p>
|
|
<p>If you plan on writing your own allocators,
|
|
<a href="../documentation.html#4">source documentation</a> is
|
|
available. You'll need to get the "maintainers" collection
|
|
in order to see the helper classes and extra notes.
|
|
</p>
|
|
<p>Return <a href="#top">to top of page</a> or
|
|
<a href="../faq/index.html">to the FAQ</a>.
|
|
</p>
|
|
|
|
<hr />
|
|
<h2><a name="4">Compile-time checks</a></h2>
|
|
<p>Currently libstdc++-v3 uses the concept checkers from the Boost
|
|
library to perform <a href="../19_diagnostics/howto.html#3">optional
|
|
compile-time checking</a> of template instantiations of the standard
|
|
containers. They are described in the linked-to page.
|
|
</p>
|
|
<p>Return <a href="#top">to top of page</a> or
|
|
<a href="../faq/index.html">to the FAQ</a>.
|
|
</p>
|
|
|
|
<hr />
|
|
<h2><a name="5">LWG Issues</a></h2>
|
|
<p>Everybody's got issues. Even the C++ Standard Library.
|
|
</p>
|
|
<p>The Library Working Group, or LWG, is the ISO subcommittee responsible
|
|
for making changes to the library. They periodically publish an
|
|
Issues List containing problems and possible solutions. As they reach
|
|
a consensus on proposed solutions, we often incorporate the solution
|
|
into libstdc++-v3.
|
|
</p>
|
|
<p>Here are the issues which have resulted in code changes to the library.
|
|
The links are to the specific defect reports from a <strong>partial
|
|
copy</strong> of the Issues List. You can read the full version online
|
|
at the <a href="http://www.dkuug.dk/jtc1/sc22/wg21/">ISO C++
|
|
Committee homepage</a>, linked to on the
|
|
<a href="http://gcc.gnu.org/readings.html">GCC "Readings"
|
|
page</a>. If
|
|
you spend a lot of time reading the issues, we recommend downloading
|
|
the ZIP file and reading them locally.
|
|
</p>
|
|
<p>(NB: <strong>partial copy</strong> means that not all links within
|
|
the lwg-*.html pages will work.
|
|
Specifically, links to defect reports that have not been accorded full
|
|
DR status will probably break. Rather than trying to mirror the
|
|
entire issues list on our overworked web server, we recommend you go
|
|
to the LWG homepage instead.)
|
|
</p>
|
|
<p>
|
|
If a DR is not listed here, we may simply not have gotten to it yet;
|
|
feel free to submit a patch. Search the include/bits and src
|
|
directories for appearances of _GLIBCPP_RESOLVE_LIB_DEFECTS for
|
|
examples of style. Note that we usually do not make changes to the code
|
|
until an issue has reached <a href="lwg-active.html#DR">DR</a> status.
|
|
</p>
|
|
<dl>
|
|
<dt><a href="lwg-defects.html#5">5</a>:
|
|
<em>string::compare specification questionable</em>
|
|
</dt>
|
|
<dd>This should be two overloaded functions rather than a single function.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#17">17</a>:
|
|
<em>Bad bool parsing</em>
|
|
</dt>
|
|
<dd>Apparently extracting Boolean values was messed up...
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#19">19</a>:
|
|
<em>"Noconv" definition too vague</em>
|
|
</dt>
|
|
<dd>If <code>codecvt::do_in</code> returns <code>noconv</code> there are
|
|
no changes to the values in <code>[to, to_limit)</code>.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#22">22</a>:
|
|
<em>Member open vs flags</em>
|
|
</dt>
|
|
<dd>Re-opening a file stream does <em>not</em> clear the state flags.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#25">25</a>:
|
|
<em>String operator<< uses width() value wrong</em>
|
|
</dt>
|
|
<dd>Padding issues.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#48">48</a>:
|
|
<em>Use of non-existent exception constructor</em>
|
|
</dt>
|
|
<dd>An instance of <code>ios_base::failure</code> is constructed instead.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#49">49</a>:
|
|
<em>Underspecification of ios_base::sync_with_stdio</em>
|
|
</dt>
|
|
<dd>The return type is the <em>previous</em> state of synchronization.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#50">50</a>:
|
|
<em>Copy constructor and assignment operator of ios_base</em>
|
|
</dt>
|
|
<dd>These members functions are declared <code>private</code> and are
|
|
thus inaccessible. Specifying the correct semantics of
|
|
"copying stream state" was deemed too complicated.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#60">60</a>:
|
|
<em>What is a formatted input function?</em>
|
|
</dt>
|
|
<dd>This DR made many widespread changes to <code>basic_istream</code>,
|
|
not all of which have been implemented.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#68">68</a>:
|
|
<em>Extractors for char* should store null at end</em>
|
|
</dt>
|
|
<dd>And they do now. An editing glitch in the last item in the list of
|
|
[27.6.1.2.3]/7.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#74">74</a>:
|
|
<em>Garbled text for codecvt::do_max_length</em>
|
|
</dt>
|
|
<dd>The text of the standard was gibberish. Typos gone rampant.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#83">83</a>:
|
|
<em>string::npos vs. string::max_size()</em>
|
|
</dt>
|
|
<dd>Safety checks on the size of the string should test against
|
|
<code>max_size()</code> rather than <code>npos</code>.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#90">90</a>:
|
|
<em>Incorrect description of operator>> for strings</em>
|
|
</dt>
|
|
<dd>The effect contain <code>isspace(c,getloc())</code> which must be
|
|
replaced by <code>isspace(c,is.getloc())</code>.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#109">109</a>:
|
|
<em>Missing binders for non-const sequence elements</em>
|
|
</dt>
|
|
<dd>The <code>binder1st</code> and <code>binder2nd</code> didn't have an
|
|
<code>operator()</code> taking a non-const parameter.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#110">110</a>:
|
|
<em>istreambuf_iterator::equal not const</em>
|
|
</dt>
|
|
<dd>This was not a const member function. Note that the DR says to
|
|
replace the function with a const one; we have instead provided an
|
|
overloaded version with identical contents.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#117">117</a>:
|
|
<em>basic_ostream uses nonexistent num_put member functions</em>
|
|
</dt>
|
|
<dd><code>num_put::put()</code> was overloaded on the wrong types.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#118">118</a>:
|
|
<em>basic_istream uses nonexistent num_get member functions</em>
|
|
</dt>
|
|
<dd>Same as 117, but for <code>num_get::get()</code>.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#129">129</a>:
|
|
<em>Need error indication from seekp() and seekg()</em>
|
|
</dt>
|
|
<dd>These functions set <code>failbit</code> on error now.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#136">136</a>:
|
|
<em>seekp, seekg setting wrong streams?</em>
|
|
</dt>
|
|
<dd><code>seekp</code> should only set the output stream, and
|
|
<code>seekg</code> should only set the input stream.
|
|
</dd>
|
|
|
|
<!--<dt><a href="lwg-defects.html#159">159</a>:
|
|
<em>Strange use of underflow()</em>
|
|
</dt>
|
|
<dd>In fstream.tcc, the basic_filebuf<>::showmanyc() function
|
|
should probably not be calling <code>underflow()</code>.
|
|
</dd> -->
|
|
|
|
<dt><a href="lwg-active.html#167">167</a>:
|
|
<em>Improper use of traits_type::length()</em>
|
|
</dt>
|
|
<dd><code>op<<</code> with a <code>const char*</code> was
|
|
calculating an incorrect number of characters to write.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#171">171</a>:
|
|
<em>Strange seekpos() semantics due to joint position</em>
|
|
</dt>
|
|
<dd>Quite complex to summarize...
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#181">181</a>:
|
|
<em>make_pair() unintended behavior</em>
|
|
</dt>
|
|
<dd>This function used to take its arguments as reference-to-const, now
|
|
it copies them (pass by value).
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#195">195</a>:
|
|
<em>Should basic_istream::sentry's constructor ever set eofbit?</em>
|
|
</dt>
|
|
<dd>Yes, it can, specifically if EOF is reached while skipping whitespace.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#211">211</a>:
|
|
<em>operator>>(istream&, string&) doesn't set failbit</em>
|
|
</dt>
|
|
<dd>If nothing is extracted into the string, <code>op>></code> now
|
|
sets <code>failbit</code> (which can cause an exception, etc, etc).
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#214">214</a>:
|
|
<em>set::find() missing const overload</em>
|
|
</dt>
|
|
<dd>Both <code>set</code> and <code>multiset</code> were missing
|
|
overloaded find, lower_bound, upper_bound, and equal_range functions
|
|
for const instances.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-active.html#231">231</a>:
|
|
<em>Precision in iostream?</em>
|
|
</dt>
|
|
<dd>For conversion from a floating-point type, <code>str.precision()</code>
|
|
is specified in the conversion specification.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#235">235</a>:
|
|
<em>No specification of default ctor for reverse_iterator</em>
|
|
</dt>
|
|
<dd>The declaration of <code>reverse_iterator</code> lists a default constructor.
|
|
However, no specification is given what this constructor should do.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#251">251</a>:
|
|
<em>basic_stringbuf missing allocator_type</em>
|
|
</dt>
|
|
<dd>This nested typdef was originally not specified.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#265">265</a>:
|
|
<em>std::pair::pair() effects overly restrictive</em>
|
|
</dt>
|
|
<dd>The default ctor would build its members from copies of temporaries;
|
|
now it simply uses their respective default ctors.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#266">266</a>:
|
|
<em>bad_exception::~bad_exception() missing Effects clause</em>
|
|
</dt>
|
|
<dd>The <code>bad_</code>* classes no longer have destructors (they
|
|
are trivial), since no description of them was ever given.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#271">271</a>:
|
|
<em>basic_iostream missing typedefs</em>
|
|
</dt>
|
|
<dd>The typedefs it inherits from its base classes can't be used, since
|
|
(for example) <code>basic_iostream<T>::traits_type</code> is ambiguous.
|
|
</dd>
|
|
|
|
<dt><a href="lwg-defects.html#275">275</a>:
|
|
<em>Wrong type in num_get::get() overloads</em>
|
|
</dt>
|
|
<dd>Similar to 118.
|
|
</dd>
|
|
|
|
<!--
|
|
<dt><a href="lwg-defects.html#"></a>:
|
|
<em></em>
|
|
</dt>
|
|
<dd>
|
|
</dd>
|
|
|
|
-->
|
|
</dl>
|
|
<p>Return <a href="#top">to top of page</a> or
|
|
<a href="../faq/index.html">to the FAQ</a>.
|
|
</p>
|
|
|
|
|
|
<!-- ####################################################### -->
|
|
|
|
<hr />
|
|
<p class="fineprint"><em>
|
|
See <a href="../17_intro/license.html">license.html</a> for copying conditions.
|
|
Comments and suggestions are welcome, and may be sent to
|
|
<a href="mailto:libstdc++@gcc.gnu.org">the libstdc++ mailing list</a>.
|
|
</em></p>
|
|
|
|
|
|
</body>
|
|
</html>
|