1996-03-18 13:38:52 +00:00
|
|
|
<HTML><HEAD><TITLE>Using Open Scripting Extension from Python</TITLE></HEAD>
|
|
|
|
|
<BODY>
|
|
|
|
|
<H1>Using Open Scripting Extension from Python</H1>
|
|
|
|
|
<HR>
|
|
|
|
|
|
|
|
|
|
OSA support in Python is still far from complete, and what
|
|
|
|
|
support there is is likely to change in the forseeable future. Still,
|
|
|
|
|
there is already enough in place to allow you to do some nifty things
|
|
|
|
|
to other programs from your python program. <P>
|
|
|
|
|
|
|
|
|
|
<CITE>
|
|
|
|
|
Actually, when we say "AppleScript" in this document we actually mean
|
|
|
|
|
"the Open Scripting Architecture", there is nothing
|
|
|
|
|
AppleScript-specific in the Python implementation. <p>
|
|
|
|
|
</CITE>
|
|
|
|
|
|
|
|
|
|
In this example, we will look at a scriptable application, extract its
|
|
|
|
|
"AppleScript Dictionary" and generate a Python interface module from
|
|
|
|
|
that and use that module to control the application. Because we want
|
|
|
|
|
to concentrate on the OSA details we don't bother with a real
|
|
|
|
|
user-interface for our application. <p>
|
|
|
|
|
|
|
|
|
|
The application we are going to script is Eudora Light, a free mail
|
|
|
|
|
program from <A HREF="http://www.qualcomm.com">QualComm</A>. This is a
|
|
|
|
|
very versatile mail-reader, and QualComm has an accompanying
|
|
|
|
|
commercial version once your needs outgrow Eudora Light. Our program
|
|
|
|
|
will tell Eudora to send queued mail, retrieve mail or quit. <p>
|
|
|
|
|
|
|
|
|
|
<H2>Creating the Python interface module</H2>
|
|
|
|
|
|
|
|
|
|
There is a tool in the standard distribution that looks through a file
|
|
|
|
|
for an 'AETE' or 'AEUT' resource, the internal representation of the
|
|
|
|
|
AppleScript dictionary. This tool is called
|
1997-08-19 14:00:56 +00:00
|
|
|
<CODE>gensuitemodule.py</CODE>, and lives in <CODE>Mac:scripts</CODE>.
|
|
|
|
|
When we start it, it asks us for an input file and we point it to the
|
|
|
|
|
Eudora Light executable. It starts parsing the AETE resource, and for
|
|
|
|
|
each AppleEvent suite it finds it prompts us for the filename of the
|
|
|
|
|
resulting python module. Remember to change folders for the first
|
|
|
|
|
module, you don't want to clutter up the Eudora folder with your python
|
|
|
|
|
interfaces. If you want to skip a suite you press cancel and the process
|
|
|
|
|
continues with the next suite. In the case of Eudora, you do
|
|
|
|
|
<EM>not</EM> want to generate the Required and Standard suites, because
|
|
|
|
|
they are identical to the standard ones which are pregenerated (and
|
|
|
|
|
empty in the eudora binary). AppleScript understands that an empty suite
|
|
|
|
|
means "incorporate the whole standard suite by this name",
|
1996-03-18 13:38:52 +00:00
|
|
|
gensuitemodule does not currently understand this. Creating the empty
|
|
|
|
|
<CODE>Required_Suite.py</CODE> would hide the correct module of that
|
|
|
|
|
name from our application. <p>
|
|
|
|
|
|
1997-08-19 14:00:56 +00:00
|
|
|
Gensuitemodule may ask you questions like "Where is enum 'xyz ' declared?".
|
|
|
|
|
For the first time, cancel out of this dialog after taking down the
|
|
|
|
|
enum (or class or prop) name. After you've created all the suites look
|
|
|
|
|
for these codes, in the suites generated here and in the standard suites.
|
|
|
|
|
If you've found them all run gensuitemodule again and point it to the right
|
|
|
|
|
file for each declaration. Gensuitemodule will generate the imports to make the
|
|
|
|
|
reference work. <p>
|
|
|
|
|
|
1996-04-19 15:56:08 +00:00
|
|
|
<BLOCKQUOTE>
|
1996-03-18 13:38:52 +00:00
|
|
|
Time for a sidebar. If you want to re-create
|
|
|
|
|
<CODE>Required_Suite.py</CODE> or one of the other standard modules
|
|
|
|
|
you should look in <CODE>System Folder:Extensions:Scripting
|
|
|
|
|
Additions:Dialects:English Dialect</CODE>, that is where the core
|
|
|
|
|
AppleEvent dictionaries live. Also, if you are looking for the
|
|
|
|
|
<CODE>Finder_Suite</CODE> interface: don't look in the finder (it has
|
|
|
|
|
an old System 7.0 scripting suite), look at the extension <CODE>Finder
|
|
|
|
|
Scripting Extension</CODE>. <p>
|
1996-04-19 15:56:08 +00:00
|
|
|
</BLOCKQUOTE>
|
1996-03-18 13:38:52 +00:00
|
|
|
|
|
|
|
|
Let's glance at the <A
|
|
|
|
|
HREF="scripting/Eudora_Suite.py">Eudora_Suite.py</A> just created. You
|
|
|
|
|
may want to open Script Editor alongside, and have a look at how it
|
|
|
|
|
interprets the dictionary. EudoraSuite.py starts with some
|
1997-08-19 14:00:56 +00:00
|
|
|
boilerplate, then a big class definition with methods for each
|
|
|
|
|
AppleScript Verb, then some small class definitions and then some dictionary
|
|
|
|
|
initializations. <p>
|
1996-03-18 13:38:52 +00:00
|
|
|
|
|
|
|
|
The <CODE>Eudora_Suite</CODE> class is the bulk of the code
|
|
|
|
|
generated. For each verb it contains a method. Each method knows what
|
|
|
|
|
arguments the verb expects, and it makes handy use of the keyword
|
|
|
|
|
argument scheme introduced in Python 1.3 to present a palatable
|
|
|
|
|
interface to the python programmer. You will see that each method
|
|
|
|
|
calls some routines from <CODE>aetools</CODE>, an auxiliary module
|
1996-04-19 15:56:08 +00:00
|
|
|
living in <CODE>Lib:toolbox</CODE> which contains some other nifty
|
1996-03-18 13:38:52 +00:00
|
|
|
AppleEvent tools as well. Have a look at it sometime, there is (of
|
|
|
|
|
course) no documentation yet. <p>
|
|
|
|
|
|
|
|
|
|
The other thing you notice is that each method calls
|
|
|
|
|
<CODE>self.send</CODE>, but no such method is defined. You will have
|
|
|
|
|
to provide it by subclassing or multiple inheritance, as we shall see
|
|
|
|
|
later. <p>
|
|
|
|
|
|
1997-08-19 14:00:56 +00:00
|
|
|
After the big class we get a number of little class declarations. These
|
|
|
|
|
declarations are for the (appleevent) classes and properties in the suite.
|
|
|
|
|
They allow you to create object IDs, which can then be passed to the verbs.
|
|
|
|
|
For instance, to get the name of the sender of the first message in mailbox
|
|
|
|
|
inbox you would use <code>mailbox("inbox").message(1).sender</code>. It is
|
|
|
|
|
also possible to specify this as <code>sender(message(1, mailbox("inbox")))</code>,
|
|
|
|
|
which is sometimes needed because these classes don't inherit correctly
|
|
|
|
|
from baseclasses, so you may have to use a class or property from another suite. <p>
|
|
|
|
|
|
|
|
|
|
<blockquote>
|
|
|
|
|
There are also some older object specifiers for standard objects in aetools.
|
|
|
|
|
You use these in the form <CODE>aetools.Word(10,
|
1996-03-18 13:38:52 +00:00
|
|
|
aetools.Document(1))</CODE> where the corresponding AppleScript
|
|
|
|
|
terminology would be <CODE>word 10 of the first
|
|
|
|
|
document</CODE>. Examine the two modules mentioned above along with
|
|
|
|
|
the comments at the end of your suite module if you need to create
|
1997-08-19 14:00:56 +00:00
|
|
|
more than the standard object specifiers.
|
|
|
|
|
</blockquote>
|
|
|
|
|
|
|
|
|
|
Next we get the enumeration dictionaries, which allow you to pass
|
|
|
|
|
english names as arguments to verbs, so you don't have to bother with the 4-letter
|
|
|
|
|
type code. So, you can say
|
|
|
|
|
<CODE><PRE>
|
|
|
|
|
eudora.notice(occurrence="mail_arrives")
|
|
|
|
|
</PRE></CODE>
|
|
|
|
|
instead of the rather more cryptic
|
|
|
|
|
<CODE><PRE>
|
|
|
|
|
eudora.notice(occurrence="wArv")
|
|
|
|
|
</PRE></CODE><p>
|
|
|
|
|
|
|
|
|
|
Finally, we get the "table of contents" of the module, listing all classes and such
|
|
|
|
|
by code, which is used by gensuitemodule. <p>
|
1996-03-18 13:38:52 +00:00
|
|
|
|
|
|
|
|
<H2>Using a Python suite module</H2>
|
|
|
|
|
|
|
|
|
|
Now that we have created the suite module we can use it in an
|
|
|
|
|
application. We do this by creating a class that inherits
|
|
|
|
|
<CODE>Eudora_Suite</CODE> and the <CODE>TalkTo</CODE> class from
|
|
|
|
|
<CODE>aetools</CODE>. The <CODE>TalkTo</CODE> class is basically a
|
|
|
|
|
container for the <CODE>send</CODE> method used by the methods from
|
|
|
|
|
the suite classes. <p>
|
|
|
|
|
|
|
|
|
|
Actually, our class will also inherit <CODE>Required_Suite</CODE>,
|
|
|
|
|
because we also need functionality from that suite: the quit
|
|
|
|
|
command. Gensuitemodule could have created this completely derived
|
|
|
|
|
class for us, since it has access to all information needed to build
|
|
|
|
|
the class but unfortunately it does not do so at the moment. All in
|
|
|
|
|
all, the heart of our program looks like this:
|
|
|
|
|
<CODE><PRE>
|
|
|
|
|
import Eudora_Suite, Required_Suite, aetools
|
|
|
|
|
|
1997-08-19 14:00:56 +00:00
|
|
|
class Eudora(Eudora_Suite.Eudora_Suite, Required_Suite.Required_Suite, \
|
|
|
|
|
aetools.TalkTo):
|
1996-03-18 13:38:52 +00:00
|
|
|
pass
|
|
|
|
|
</PRE></CODE>
|
|
|
|
|
|
|
|
|
|
Yes, our class body is <CODE>pass</CODE>, all functionality is already
|
|
|
|
|
provided by the base classes, the only thing we have to do is glue it
|
|
|
|
|
together in the right way. <p>
|
|
|
|
|
|
|
|
|
|
Looking at the sourcefile <A
|
|
|
|
|
HREF="scripting/testeudora.py">testeudora.py</A> we see that it starts
|
1996-04-19 15:56:08 +00:00
|
|
|
with some imports. Then we get the class definition
|
1996-03-18 13:38:52 +00:00
|
|
|
for our main object and a constant giving the signature of Eudora. <p>
|
|
|
|
|
|
|
|
|
|
This, again, needs a little explanation. There are various ways to
|
|
|
|
|
describe to AppleScript which program we want to talk to, but the
|
|
|
|
|
easiest one to use (from Python, at least) is creator
|
|
|
|
|
signature. Application name would be much nicer, but Python currently
|
|
|
|
|
does not have a module that interfaces to the Finder database (which
|
|
|
|
|
would allow us to map names to signatures). The other alternative,
|
|
|
|
|
<CODE>ChooseApplication</CODE> from the program-to-program toolbox, is
|
|
|
|
|
also not available from Python at the moment. <p>
|
|
|
|
|
|
1996-09-20 15:22:47 +00:00
|
|
|
If you specify the application by creator you can specify an optional
|
|
|
|
|
<CODE>start</CODE> parameter, which will cause the application to be
|
|
|
|
|
started if it is not running. <P>
|
|
|
|
|
|
1996-03-18 13:38:52 +00:00
|
|
|
The main program itself is a wonder of simplicity. We create the
|
|
|
|
|
object that talks to Eudora (passing the signature as argument), ask
|
|
|
|
|
the user what she wants and call the appropriate method of the talker
|
|
|
|
|
object. The use of keyword arguments with the same names as used by
|
|
|
|
|
AppleScript make passing the parameters a breeze. <p>
|
|
|
|
|
|
|
|
|
|
The exception handling does need a few comments, though. Since
|
|
|
|
|
AppleScript is basically a connectionless RPC protocol nothing happens
|
|
|
|
|
when we create to talker object. Hence, if the destination application
|
|
|
|
|
is not running we will not notice until we send our first
|
|
|
|
|
command. There is another thing to note about errors returned by
|
1996-11-20 15:13:24 +00:00
|
|
|
AppleScript calls: <CODE>MacOS.Error</CODE> is raised for
|
|
|
|
|
all of the errors that are known to be <CODE>OSErr</CODE>-type errors,
|
|
|
|
|
server generated errors raise <CODE>aetools.Error</CODE>. <p>
|
1996-03-18 13:38:52 +00:00
|
|
|
|
1996-12-23 17:28:53 +00:00
|
|
|
<H2>Scripting Additions</H2>
|
|
|
|
|
|
|
|
|
|
If you want to use any of the scripting additions (or OSAXen, in
|
|
|
|
|
everyday speech) from a Python program you can use the same method
|
|
|
|
|
as for applications, i.e. run <CODE>gensuitemodule</CODE> on the
|
|
|
|
|
OSAX (commonly found in <CODE>System Folder:Extensions:Scripting Additions</CODE>
|
|
|
|
|
or something similar), define a class which inherits the generated
|
|
|
|
|
class and <CODE>aetools.TalkTo</CODE> and instantiate it. The application
|
|
|
|
|
signature to use is <CODE>'MACS'</CODE>. <P>
|
|
|
|
|
|
|
|
|
|
There are two minor points to watch out for when using gensuitemodule
|
|
|
|
|
on OSAXen: they appear all to define the class <CODE>System_Object_Suite</CODE>,
|
|
|
|
|
and a lot of them have the command set in multiple dialects. You have to
|
|
|
|
|
watch out for name conflicts, so, and make sure you select a reasonable dialect
|
|
|
|
|
(some of the non-english dialects cause gensuitemodule to generate incorrect
|
|
|
|
|
Python code). <P>
|
|
|
|
|
|
1996-03-18 13:38:52 +00:00
|
|
|
That concludes our simple example. Again, let me emphasize that
|
|
|
|
|
scripting support in Python is not very complete at the moment, and
|
|
|
|
|
the details of how to use AppleEvents will definitely change in the
|
|
|
|
|
near future. This will not only fix all the ideosyncracies noted in
|
|
|
|
|
this document but also break existing programs, since the current
|
|
|
|
|
suite organization will have to change to fix some of the problems.
|
|
|
|
|
Still, if you want to experiment with AppleEvents right now: go ahead!
|
|
|
|
|
<p>
|
