fibre~thread

Cappuccino Machine

paul — Wed, 12 May 2010 03:00:43 +0000

I would call this post: “In a realm of all things cool Cappucino starts to rule”. I’ve noticed the framework a while ago but never quite had the time to sit down and start writing the “Hello World”. In my (graphics developer) vernacular that would be an animated ‘dot’ running around in circles. Here it goes… a bit slow, but does the job. I imagine it easy enough to improve the speed the animation by layer-backing the ‘dot’. Enjoy..

A subtlety of object identity in Obj-C

paul — Fri, 26 Feb 2010 19:02:31 +0000

A problem: given an object a of class A that aggregates a publicly accessible instance of class B determine if an instance changed by polling periodically. This comes up often in concurrent systems where an object change warrants a response while KVO is undesirable. The first thought that comes to mind is to a cache the instance of B during each cycle of polling after the comparison of the cached instance to the present value.

Our code might look like this

if (cachedB != [a valueOfB]) { triggerEvent(...); }
cachedB = [a valueOfB];

Unfortunately this fails miserable due to the fact that a newly allocated instance of B may occupy the same memory location as the previous one (assuming, of course, that we never retain the cached value). This is a low probability failure and is extremely hard to debug. This bug is solved by storing a timestamp upon change of instance of B inside a, and cacheing it instead of the memory address.

Joy

paul — Wed, 24 Feb 2010 21:49:15 +0000

Authentic joy is everlasting
A thing that freely permeates
As born in hearts of lovers lusting
So nascent is when we create

It hides itself in child’s smile
In ray-ing clouds of sunrise
It so resides in every shining
Of every memorable time

@rpath

paul — Wed, 10 Feb 2010 02:36:19 +0000

Leopard and (Sno) have a new way of specifying deployment location of a dynamic lib. Follow this link for an in depth explanation.

Command line is your friend :)

paul — Wed, 10 Feb 2010 00:44:14 +0000

A nifty command python -m SimpleHTTPServer will start serving the current directory on port 8000. Seems like a cute alternative to broken iChat transfers… found it here among other cute Linux miscellanea.

When in doubt about missing symbols during linking nm can be an invaluable asset. When struggling with questions about architectures of a binary otool -vf is the there to help.

Examining view hierarchy at runtime

paul — Tue, 01 Sep 2009 07:08:47 +0000

If ever in need to examine a view hierarchy at runtime HTViewHierarchy is your friend. It is a superb reverse engineering tool. F-Script can be used to this end to a degree, but sometimes one just needs a hierarchy browser.

Modifying dynamic linker paths

paul — Wed, 20 May 2009 18:03:05 +0000

There times when standard locations for libraries and frameworks just don’t cut it. For such times a lineup of environment variables can be used to guide the linker. Typing

man dyld

in the terminal tells the story. Also

otool -L <executable-name>

lists library locations for a given executable.

Building CGAL 3.3.1 on (10.5) Leopard

paul — Wed, 29 Apr 2009 20:01:12 +0000

Not an exercise for the faint of heart. In fact this applies to using it in your programs as well. While I managed to build the libs, I never managed to build the demos that rely on Qt.

Download the mac distribution from CGAL portal.

Prior to installing CGAL you need to have a few prerequisites on your system: boost, GMP, MPFR, Qt (3 didn’t manage to get it working with 4)

It is easiest to use macports to get these. After downloading and installing macports install the libraries as follows

sudo port install boost
sudo port install GMP
sudo port install MPFR
sudo port install qt3-mac

You may also wish to install qt4 by invoking

sudo port install qt4-mac-devel

Open your terminal window and cd to CGAL home directory

Copy (rename) boost program_options library file so the installer picks it up by going into /opt/local/lib and type

cp libboost_program_options-mt.a libboost_program_options.a

Invoke ./instal_cgal -i to enter interactive mode of their installer

Provide the paths the installer cannot find automatically (they are all in /opt/local/include and /opt/local/lib)

Before building examples (from examples directory invoke make) don’t forget to set an environment varible

export CGAL_MAKEFILE=<path_to_CGAL-3.3.1>/make/makefile_i386_Darwin-9.6_g++-4.0.1

Backported LogKit to Tiger

paul — Tue, 14 Apr 2009 04:19:34 +0000

Backporting LogKit to Tiger proved to be a pain in the neck. Crossdevelopment is tedious and the macros-riddled code looks ugly. On the upside I fixed a few bugs and reorganized the projects. The current release SymbicLogKit 0.92 is tested under both Tiger (10.4.11) and Leopard and includes source for both the framework and examples.

To include SymbicLogKit in your own projects follow these steps:

Add SymbicLogKit as a dependent project to your project.
SymbicLogKit is built as a private framework so you will need to add a “Copy” stage to your target to place SymbicLogKit into a Frameworks subdirectory of your build product.
Make your target dependent on the principal target of SymbicLogKit project.
Now we need to tell the compiler where to look for the SymbicLogKit.framework since it isn’t available for inclusion in the project (it doesn’t exist yet). Modify Framework Search Paths setting in your build settings per configuration to point to the appropriate directory relative, for instance, to your project location e.g. $(PROJECT_DIR)/../SymbicLogKit/build/Release.
Since the framework isn’t available for inclusion in our host project we will be weak-linking to it. Locate Other Linker Flags in you build settings and set it or augment it to include -weak_framework SymbicLogKit -framework SymbicLogKit
You may want to uncheck Build Active Architecture Only build setting.

A cute way to log in as root

paul — Wed, 08 Apr 2009 00:20:26 +0000

In Leopard one can obtain the a terminal without enabling the root account. Just type “sudo su” and provide your user password. Seems like a cleaner way to operate as root.