According to Hoyle...
Mac OS X
10.6 Snow Leopard Preview
by Jonathan Hoyle
Last month we reviewed this year's Worldwide Developer Conference, the all-important Apple conference for
programmers, engineers and and other technically inclined Mac person. Although much of the media blitz was
over the new iPhone, most conference attendees found the information
about the new upcoming Mac
OS X 10.6 Snow Leopard release
to be of greater importance.
Much of what is discussed at WWDC is covered under Apple's
Non-Disclosure Agreement. Now,
admittedly, it doesn't take a great deal to get into the "secret
circle"...essentially, you must simply sign up for a free Apple Developer
Connection membership, electronically check the confidentiality clause, and boom all of Apple's free
online information is there for your perusal. However, since this article is outside this arena, I will
being covering only those areas available to the general public, and I'll make
suggestions as to where to look for those who do have memberships and wish to
What is not hidden behind the shroud of Apple secrecy? One thing which is you can usually
count on is that the Steve Jobs keynote address is freely accessible, as Steve
likes to use this pulpit to preach to the unconverted. Unfortunately, this year's sermon did
not cover the Macintosh at all but rather the iPhone. This is very annoying to be sure, but fortunately, Apple has
released a lot of public information about Snow Leopard through other avenues,
such as press releases, web pages and information posted about WWDC itself.
For a high level overview on what Mac OS X 10.6 Snow Leopard has to offer, visit Apple's web page on it.
One of the biggest rumors spreading about was that Snow Leopard would be Intel-only. This is hardly much of a surprise, given that Apple
announced its Intel products over three years ago, and stopped selling
PowerPC-based Macs as of two years ago.
Many developers were expecting this for some time now, so it would have
been more surprising if it were not true.
Just days before WWDC, however, Gizmodo.com predicted just the opposite: that PowerPC
was going to be a supported platform for Snow
Leopard. Unfortunately, Gizmodo's reasoning was
faulty: it assumed that the existence of PowerPC-based drivers in the OS
implied that the OS will target PPC.
An Intel-only version of Mac OS X would still require PowerPC-based
drivers simply because Rosetta emulated applications will need them. Since Rosetta will be around for at
least until 10.7 or 10.8, we can expect to see PowerPC-built drivers (at least
the 32-bit versions) around for a while.
As you are probably already aware by now, the original prediction
was correct: Snow Leopard is indeed Intel-only. Although I cannot find any Apple-authorized statement to
this affect, but Snow
Leopard's actual system
requirements have already been released through dozens of web sites, including MacUser, Ars Technica, MacNN, Softpedia, Apple Gazette, OS News, the Unofficial Apple
Weblog, and many, many others. I can
only assume that Apple verbally confirmed this to the news outlets, as I do not
find any publicly released statement to that affect on Apple's web site. In any case, the cat is out of the bag,
so I guess there is no harm in confirming that this is indeed true, as I can
attest: having a Snow
Leopard Prerelease DVD of my
A Thinner Fat
Of course, what this means is that for those compiling applications
to run on Snow Leopard only, you need to compile only for two way Fat: Intel
32-bit and Intel-64-bit. Indeed,
one could change that and to an or and make it one-way Fat: as most Intels out
there today support 64-bit. For
DLL and plugin developers, you will want to compile your programs as three way
Fat: Intel-32, Intel-64 and PowerPC-32.
Why is that? Well, simply a
DLL or plugin must match the architecture of the host application, which loads
it, and these are the only three types of applications that will run on Snow Leopard.
(Recall that the PowerPC emulation provided by Rosetta is 32-bit only). Even for those wishing to support both 10.5 Leopard and 10.6
Snow Leopard in their builds,
there is a very strong argument for dropping PowerPC 64-bit support: namely
that PPC-64 lived and died in 10.5
Leopard, and only the highest
end G5 machines would even be able to run such applications. Furthermore, some of the technological
advances in compiler options do not even bother to support PPC-64 (see
below). Those developing in Java
have already seen this limitation: 64-bit Java has always been Intel only.
Xcode Marks the Spot
Whether Apple actually intended to publicly release information
about Xcode 3.1 I do not know, but publicly released they
did. On the non-member version of their WWDC web site (which is indeed
public), they give the following description about Session #907: New Compiler Technology and Future
Xcode 3.1 introduces two new compilers for Mac OS X: GCC 4.2 and
LLVM-GCC. Learn how the new security and performance improvements in GCC 4.2
can help you produce better applications. Understand the innovations in
LLVM-GCC, and find out how you can use it in your own testing and development.
Finally, get a preview of future compiler developments.
This of course announces a couple of things: that the next version of Xcode is called 3.1, it will be able to use gcc 4.2 (a vastly improved version of gcc, which has remained stagnant at 4.0.1 for about three years now),
and Xcode 3.1 will be able to opt for the newest and most
powerful technology LLVM.
Since both gcc
are open source projects, you can see what these new compilers have to offer
without having to limbo under Apple's NDA pole. I will go into further detail on these compilers in a future
article, but I can assure you that this is great news for Mac developers.
For those who have not already done so, it's simply time to say goodbye to the old gcc 3.3 world.
gcc 4.2 is binary compatible with gcc 4.0, so you can mix and match these. But gcc 3.3 is
dead (and should have been made so before now).
Sadly, I do not
see many article written about the new Xcode, despite the fact that so much of it is public domain
When is an Upgrade not an Upgrade?
One of the announcements about Snow Leopard which has caused a great
deal of confusion has to do with its feature set; or better stated: its lack
thereof. Without the whiz-bang
features found in the previous releases of Mac OS X,
many people are mistakenly viewing 10.6 as merely a bug fix release, more aptly
named 10.5.5. This is far from the
truth. Although there are
virtually no user-level features, the infrastructural changes abound,
making them all worthwhile. You
may recall that the 10.1 release of Mac OS X was essentially the same
thing. And frankly, it's high time
Apple did it again. With all of
the new widgets and features added to 10.4
Tiger, followed by the dump
truck pouring of features in 10.5
Leopard, performance tuning and
framework updates are a welcome substitute to yet more features. With the dropping of the PowerPC
platform, Apple has a great opportunity now to truly concentrate on these kinds
of improvements. Will it be worth the
$129 they'll likely be asking for it?
You're damn right it will.
One essential and powerful new addition to Snow Leopard is the ease with which developers can finally
take advantage of all those extra cores in the computer. Until now it was exceedingly difficult
for a developer to create multithreaded code. The overhead and headaches involved with pthread's and
mutexes can be enormous (as I know, having to deal with them day to day). How many cores are on the machine? How many are actually available. I might take a great deal of time to
implement a threaded design to improve performance on one machine, just to find
it hinders performance on another.
Yuck. This is why so many
programs are single threaded and waste all of that extra processing power your
Mac has to offer.
Leopard, all of that
changes. Now it becomes very easy
for the developer to write his code in such a way that it will dynamically take
advantage of extra cores (if they exist) and to skip it otherwise. In this day where processor speeds are
beginning to plateau but processor and core numbers are increasing, this is the
best path forward for application design.
There are several technologies available to the Mac developer to
choose from. The Cocoa developer will like find Grand Central, an Objective-C
based approach which will make multithreaded development a breeze. This is a great improvement over the
creaky NSOperation class formerly available. For graphics and mathematical developers, the new OpenCL API
takes great advantage of the hardware's power and speed, particularly for the
GPU. The C++ developer will likely
find gcc 4.2's OpenMP protocol (a cross-platform API) to be just what
the doctor ordered. And unlike the
other options I just mentioned, this is open source so is publicly available
now. I gave a brief code example of its use an article last year.
Carbon Dating Yourself
For those who have not gotten the message yet, a look at this past
WWDC schedule would see now Carbon session, only two labs (and both of these as
transitions to Cocoa). I too am
finding it a bit painful to kick the Carbon habit, as it has been my fluency
back to the original Toolbox days of the mid 1980's. Unfortunately, Steve Jobs has spoken, and he has dealt a
death blow to Carbon. We may
mourn, but we also must move on.
The Cocoa framework itself seems interesting enough, but it's simply
getting past that damn fugly Objective-C syntax which is the hard part. When your eyes wince at reading such
code, it is not a very attractive proposition. Luckily, you have Uncle Jonathan here willing to take one
for the team for you. Next month,
I will spend an entire column devoted to C/C++ programmers and how to minimize
the pain of Objective-C and exactly what all those damn brackets really mean.
Watch Your Language
If after all the brainwashing and Kool Aid you still don't like
Objective-C, fear not. With the
latest versions of Xcode, you will be able to develop first class applications
using alternative languages such as Ruby, Python and even AppleScript. Start with Interface Builder to create
your GUI, but simply use your language of choice for coding. Although Onjective-C remains the
favorite son (getting all the cool new features first), there is no reason you
should ignore these alternatives if they suit your needs. I will spend time in a future article
on this particular feature.
A Kernel of Truth
At WWD 2007, Steve Jobs claimed that Mac
OS X 10.5 Leopard was 64-Bit
"Top to Bottom". Well,
sadly, this was simply untrue.
Despite the claims, the OS kernel in Leopard
remained 32-bit. As of Snow Leopard though, the 64-bit kernel will arrive and save
Steve from his departures from reality.
For most developers, this change will be transparent, as 32- and 64-bit
apps will continue to run side-by-side.
However, those writing kernel extensions will have to change their
compiler options from two-way Fat to three-way Fat. (No PPC-64 kernel ever existed, so this architecture can be
ignored). More on this also in a
Coming Up Next Month: Too
embarrassed to ask what all that Objective-C grunge means? Don't Panic, I will hold your hand
through to get you to understand what Objective C is all about. See you in 30!
To see a list of all the According to Hoyle columns,