4 Comments

1. has
   Posted July 7, 2007 at 5:11 am | Permalink

   Regarding using ObjC in place of AppleScript, check out objc-appscript if you haven’t already done so:

   http://appscript.sourceforge.net/objc-appscript.html
   

   However, don’t expect a straight translation from AS to ObjC to automatically provide vast performance improvements. While the AppleScript language certainly has its share of performance problems, Apple event IPC has various bottlenecks of its own which you need to be aware of.

   Basically, there are two problems dealing with large data sets in AppleScript:

   1. The first is that iterating over AS lists normally has O(n*n) efficiency, although there are known kludges you can use to get it down to O(n).

   Alternatively, switching to another language (Python, Ruby, ObjC, etc.) lets you avoid that problem entirely.

   1. The second is the overheads associated with Apple event IPC. While sending interprocess events is much more efficient than in pre-OS X days, it’s still slow compared to local procedure calls. It can also take a non-trivial amount of time for the target process to resolve object specifiers and perform commands.

   Switching languages won’t help you here; your only option is to minimise the number of events you send wherever possible, e.g. sending a few more complex events:

   tracks_ref = app('iTunes').playlists[1].tracks
   names = tracks_ref.name.get
   artists = tracks_ref.artist.get
   albums = tracks_ref.album.get
   names.zip(artists, albums).each do |name, artist, album| 
       # do stuff here
   end
   

   is far, far more efficient than sending many simpler ones:

   track_list = app('iTunes').playlists[1].tracks.get
   track_list.each do |track|
       name = track.name.get
       artist = track.artist.get
       album = track.album.get
       # do stuff here
   end
   

   There are some notes about performance optimisation in the appscript documentation, and I think Matt Neuburg also discusses these issues in his AppleScript book.

   HTH

   has

   http://appscript.sourceforge.net http://rb-appscript.rubyforge.org

   Reply
2. Mike
   Posted July 7, 2007 at 7:49 am | Permalink

   Thanks for the great tips! I’ll check those things out – it’d be nice to reduce the bottleneck that is AS as much as possible.

   Reply
3. Mike
   Posted July 7, 2007 at 9:14 am | Permalink

   This is great – Appscript is going to save so much time. I’m glad you mentioned it!

   Reply
4. Bjorn
   Posted August 22, 2007 at 6:09 pm | Permalink

   Great stuff! I say thnx and looking forward of the next release.

   Reply