Mac Forum / Programming / Perl / March 2008

On Dec 8, 2007, at 7:06 PM, Celeste Suliin Burris <csburris@earthlink.net

Not quite. I forget the details at the moment, but Finder aliases are  
kind of like "firm links": while hardlinks point to inodes, and  
softlinks point to file pathnames, aliases point to the logical file  
in a more robust way than symlinks. For example, if the reverent file  
moves, symlinks break, but aliases shouldn't.

If you really want aliases, I think the CPAN modules of Dan Kogai and  
Chris Nandor are the place to start. I forget who wrote what, but  
modules like (I think) MacOS::File and Mac::Glue can either make the  
right calls directly, or leverage Applescript / OSAscript to do this  
for you.

Or if symlinks/softlinks are enough, just use the traditional Perl /  
Unix methods to make those.

If you're not into the O-O stuff involved with the AppleScript modules, and you're not in a hurry, it's possible to invoke the osascript tool from within perl using backticks. You can create a string of AppleScript commands to pass to it with simple perl concatenations like ".=" or you can use a << "here" document with perl's here or with shell's here depending on how you set the backticks.

Test your AppleScript code with Script Editor first.

Using Finder is pretty much required because Finder "owns" the specification for an alias file. I have never seen a formal description of that or, for that matter, an alias resource. They are based on the file-id number which never repeats as files are created on a partition but there is more to it because that doesn't always work. Aliases do survive a file name change by the user and they use volume names so that Finder can request a floppy by name if an old alias pops up. What can cause an alias to fail is an editor that always writes the changed file to a newly created copy and then changes the names around so the original becomes the backup. The alias will point to the original while a symbolic link will point to the new.

Also, you can do:

  use Mac::Glue ':all';
  my $finder = new Mac::Glue 'Finder';
  print $finder->make(
     new => 'alias',
     at  => $finder->prop('desktop'),
     to  => $finder->obj(file => "/Users/peter/thefile.cpp")
   # or:
   # to  => $finder->obj(alias => "Harddisk:Users:peter:thefile.cpp")
  );