My problem with AppleScript is its patchy documentation and the needless complexity of its syntax. I am also crippled by my two decades’ experience of using more consistently designed programming languages.
So, for example, when faced with the task of writing a program that writes a few hundred lines to a file, my first idea would be to open the file, write each line one at a time, then close the file. This way the operating system takes care of buffering the data in an efficient manner.
The first hurdle is how to
get the file name!
I wanted a way to find the user’s home directory, so that
I might place the output file there.
AppleScript has some things (properties? functions?) starting
with path to that supply the file names of
folders. I know this from one of their sample scripts, which
uses path to temporary items folder as string.
It is not described in the reference manual or any other
documentation I have found.
After some guesswork I hit upon path to desktop
folder. Not quite what I wanted, but close enough.
The problem is, when I try to assign file (path to desktop
folder as string) & "xyzzy.xml" to a variable (which I
will then use to open a file), I get the inscrutable error
message ‘Cannot get Macintosh
Disk:Users:pdc:Desktop:xyzzy.xml’. In the end I worked
out that my mistake was in trying to convert the name of a
non-existing file to a file name; the construct
‘file fileName’ is only
permitted if (A) the file already exists, or (B) the
command the expression is used in will create the file itself.
Or this is my deduction after an exasperating waste of time.
At this point I just had to give up on trying to work with AppleScript in the way I normally do programming, which is to work out what I want to do and then use the documentation to discover how to do it. Instead I have resorted to voodoo programming: slavishly copying snippets of sample code and resisting the urge to modify, tweak or improve anything for fear of breaking the spell. The only documentation for writing to files I have found on Apple’s web site is a subroutine for writing a whole file at once. I attempted to apply logic, reason and cunning to extrapolate from this a way to write the file piece by piece, but in the end the meaningless error messages mean this effort is futile. Accumulating the data in memory is much less efficient, but at least I might be able to make it work.
So, in the end, I have managed to extract information from iPhoto in to an XML file, and as a result am in a position to do the rest of the work I want in the Python language. For which I am very grateful!
Update: I spoke too soon. The script now silently fails to write the data to the file. Everything works as before, except the output file is empty. How fucking pathetic is that?!