Copyright 2002 Herb Sutter
These are heady times for C++. Active standardization was put
on hold after the C++ Standard was published in 1998, to give us
time to fix bugs and let compilers and libraries catch up. Now
things are "hot" again, and a lot of exciting stuff is
happening.
This new column is about precisely that "exciting stuff."
Titled "The New C++," it focuses on the active work now under way
to extend the C++ language (not much) and library (very much) now
and in the next few years as we progress toward "version 2.0" of
the C++ Standard.
There's a lot to cover, and this is where you'll find the most
up-to-date coverage. Some of us have already written a bit about
the new C++ in other fora: for more overview information about
where we're at and what (and why) exciting things are now
happening, see the two complementary columns by me and Matt
Austern in the January 2002 issue of CUJ [1,
2].
They contain some basic information about what's going on, who's
going on about it, and — perhaps most importantly of all — how
you can participate and how it affects your work
today and in the short term, not just years down the road.
A Roadmap
In this, the first installment of "The New C++," I am going to
start with a complementary bird's-eye roadmap of where we've been
and where we're going, and then I'm going to devote most of this
introductory column to just that — introductions, of people and
groups and terms, a "who's who" and "glossary" to the C++
standardization process. In future columns, I'll describe in more
technical detail some of the key facilities being considered, how
they work, and what issues come up as they're debated in committee
and between meetings on the committee email reflectors.
Figure 1 shows the major pieces influencing the
development of the C++ Standard, both in leading up to C++98's publication
in 1998 and C++0x's publication at some future time. This picture should
give you a useful roadmap of how various items work and connect, and what
leads to what else at about what time. The rest of this column defines the
terms used in Figure 1. And for now, I won't say
much more than that, but I do hasten to point out one thing in particular:
Boost is by no means the only, or even necessarily the major, outside contribution
to the Library TR (Technical Report); it just happens to be the most visible
single group at this time.
Dramatis Personae
Here is a brief summary of the individuals and organizations
who are the major players in the past and future C++ development
process.
ANSI: The American National Standards Institute. At ANSI
meetings, the rule is "one company (or individual representing
themselves), one vote." Within ISO meetings, ANSI's delegation is
the delegation for the United States and thus receives one vote,
just as the delegations for other countries represented at the
meeting each get one ISO vote. Still, because of the United
States' predominant role in the software industry in general and
in C and C++ in particular, ANSI is something of a "first among
equals" in practice at WG14 and WG21 meetings.
ANSI J11: The ANSI C committee.
ANSI J16: The ANSI C++ committee. J16 always meets
together simultaneously with ISO WG21 (this being one expression
of its "first among equals" status). For the past two years it has
also met at the same location, and in an adjacent week, as J11 so
as to promote cross-committee communication.
AT&T: AT&T Bell Labs (now AT&T Research) is
where C++ began life in the early 1980s, the brainchild of Bjarne
Stroustrup. AT&T offered C++ for standardization and WG21/J16
work began in 1989/1990.
Boost: The "C+ Boost" effort was originated just after
the C++98 Standard was passed in order to start working on
developing "existing practice" for the next round of active
standardization. Initially predominantly composed of standards
committee members, the current membership has grown much wider.
See <www.boost.org>.
CWG (Core Working Group): The "subcommittee" within
WG21/J16 that focuses on core language issues, such as namespaces,
templates, and so forth.
HP: Hewlett-Packard, where Alex Stepanov and Meng Lee
invented the revolutionary STL (Standard Template Library), much
of which was incorporated into the draft C++ Standard in 1995 and
subsequently refined within WG21/J16.
EWG (Evolution Working Group): The newest "subcommittee"
within WG21/J16, which first met in October 2001, that focuses
specifically on directions for C++0x.
ISO: The International Organization for Standardization.
ISO is not an acronym, however; it comes from the Latin word for
"the same." At ISO meetings, the rule is "one country, one vote."
(There is some discussion going on lately about changing this, but
for now that's still the rule.)
ISO WG14: ISO C committee. Within the ISO organization,
the technical working group responsible for C is JTC1/SC22/WG14,
usually shortened to WG14.
ISO WG21: ISO C++ committee [3].
Within the ISO organization, the technical working group
responsible for C++ is JTC1/SC22/WG21, usually shortened to WG21.
WG21 always meets together simultaneously with ANSI J16. For the
past two years it has also met at the same location, and in an
adjacent week, as WG14 so as to promote cross-committee
communication.
LWG (Library Working Group): The "subcommittee" within
WG21/J16 that focuses on standard library issues, such as
containers, algorithms, streams, and so forth.
PWG (Performance Working Group): The "subcommittee"
within WG21/J16 that focuses on the Performance Technical Report,
which is not shown further here as it's not as directly concerned
with C++ language and library features as experienced by users
(compared to, say, Defect Reports and corrections in the TCs, and
new features in C++0x).
Bjarne Stroustrup: The creator of C++ and author of its
first compiler, Cfront. Stroustrup continues to be active in C++
standardization and currently chairs the fledgling C++0x EWG at
WG21/J16 meetings.
Alex Stepanov: The principal creator of the STL adopted
as a large part of the standard C++ library.
Further Glossary
Besides the above persons and organizations, there are some
other common names that deserve definition. They'll be bandied
about regularly in this column:
ARM C++: C++ as of 1990. "The ARM" is an acronym for the
book titled The Annotated C++ Reference Manual [4].
The ARM was used as the base document to begin the C++
standardization effort.
C++98: The first official ISO/ANSI C++ Standard,
published in 1998. Officially known as ISO/IEC IS
14882:1998(E).
C++0x: The second official ISO/ANSI C++ Standard, which
is getting under way now and will be published in coming years (no
date yet).
C99: The second official ISO/ANSI C Standard, published
in 1999. This standard contains much that the C++ committee can be
expected to adopt wholesale, or with minor modifications, as part
of C++0x. After all, it's clear that the C++ committee values C
compatibility, and the C committee has helped us by likewise
valuing C++ compatibility, which has made some of C99's features
easier to integrate into C++0x than they might otherwise have
been. There are still some C99 features, however, that C++0x
cannot easily adopt in their C99 form, because conflicting
facilities already exist in C++98 (for example, complex is
a class template in C++98 and a keyword in C99).
Library Extensions TR (Technical Report): Starting in
2001, WG21/J16 began actively soliciting and evaluating proposals
for extensions to the C++98 Standard library. These are being
collected for later publication in the form of a "Library
Extensions" TR, which is officially non-normative, but don't kid
yourself — as with the draft standard of C++ in the early and
mid-1990s, vendors will be tracking this closely and implementing
facilities as quickly as they can. Why? Because this TR, although
non-normative in itself, is specifically intended to be added
wholesale and verbatim into the coming-and-will-be-very-normative
C++0x Standard.
STL: The groundbreaking STL developed by Alex Stepanov
and Meng Lee at Hewlett-Packard Labs in the early 1990s. Most of
the HP STL was adopted in 1995 and then refined to become the
"containers, iterators, and algorithms" portion of the C++98
Standard library.
TCI (Technical Corrigendum 1): Completed in 2001, the
first "mid-course correction" (a.k.a. "patch," a.k.a. "service
pack," a.k.a. "maintenance release") to the C++98 Standard.
Contains the resolutions to Defect Reports submitted by the global
C++ community.
TC2 (Technical Corrigendum 2): As we continue working on
the Library TR and C++0x, there will no doubt continue to be
resolutions to still-pending and not-yet-received Defect Reports.
Depending on the timing of C++0x, these may be issued in the form
of a second TC.
Next Time
Because of publishing lead times, even on the Web, I expect to
finish writing two more installments of this column before the
next C++ standards meeting in April 2002. Next time: a survey of
the first batch of suggested library extensions considered at the
October 2001 WG21/J16 meeting in Redmond, Washington, USA. The
next time after that: a closer look at one of the proposed
facilities. Stay tuned.
References
[1] Herb Sutter. "Sutter's Mill: Toward a
Standard C++0x Library, Part 1," C/C++ Users Journal,
January 2002.
[2] Matt Austern. "The Standard Librarian: And
Now for Something Completely Different," C/C++ Users
Journal, January 2002, <www.cuj.com/experts/2001/austern.htm>.
[3] The official WG21 website is at <http://std.dkuug.dk/jtc1/sc22/wg21/>.
[4] Margaret Ellis and Bjarne Stroustrup. The
Annotated C++ Reference Manual (Addison-Wesley, 1989).
Herb Sutter is an independent consultant and secretary
of the ISO/ANSI C++ standards committee. He is also one of the
instructors of The C++ Seminar (<www.gotw.ca/cpp_seminar>).
Herb can be reached at hsutter@acm.org.
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