(destructuring-bind (a b (c d)) '(1 (2 3) (4 (5 6)))
    "Should be 1 (2 3) 4 (5 6)"
    (list a b c d))

The Property List Editor (plist editor for Mac) is at

/Developer/Applications/Utilities/Property List Editor.app

You get it when you install Xcode.

Mac environment variables are set by adding them to

  ~/.MacOSX/environment.plist.

Don't add an entry for $PATH there, though. I'm still reeling from that.

To convert to/from hexidecimal in emacs, it's advised to use M-x calculator instead of M-x calc. The single-quote key (M-x calculator-rotate-displayer) will eventually get you to the point that you're outputting with the correct formatter (instead of scientific notation). Then:

• H to switch to hex i/o
  
• C-y to yank a hex number in
  
• D to switch to decimal
  
• M-x calculator-copy to copy the number
  
• backspace to clear the number from calculator
  

Then it's just on the killring and you can C-x o over and yank it.

Reverse the lines in a pipe with

( cat -n | sort -nr | cut -f 2- )

I hear there's something called 'tac' to do this, but I don't have it on my Mac (and can't find it in ports).

The gcc argument to print out all the preprocessor macros and their
definitions is -E -dD. (The -E is 'preprocess only and output to
stdout', the -dD is 'dump definitions'.) Make sure that
-fmessage-length is not set to 0 and probably you don't want -quiet
either if you're doing this inside Xcode.

On MacOS / iPhone OS, NSNotificationCenter is the implementation of
signals/slots, like Boost.Signals.