[Orbit-python-list] PyORBit

[James H. <ja...@da...>]

Christian told me that people had been asking about PyORBit here, so I 
thought I would explain some of the design decisions.

My main aim was to produce an ORBit2 binding for use with the GNOME 2.x 
python bindings.  This is the reason for the "Where it makes sense, this 
binding tries to stay compatible with the Python language mapping" 
language.  This does not mean that I am going to make it gratuitously 
incompatible (in some areas, PyORBit follows the standard more closely 
than o-p).

PyORBit makes use of new style types.  Since PyORBit was intended to be 
a binding for use by the GNOME bindings which already require Python >= 
2.2, I didn't consider this a problem.  IMHO, this has led to much 
simpler code.

PyORBit makes use of ORBit2 typelibs.  Typelib information is fairly 
central to the way ORBit2 works, so this made a lot of sense.  It 
allowed me to make use of the ORBit_small_invoke_stub() method, which 
speeds up in-process method invocations, as it skips marshalling to/from 
IIOP representation.

PyORBit supports invoking methods on in-process CORBA objects 
implemented in C.  It also allows C code to invoke methods on in-process 
CORBA objects implemented in Python (modulo Python interpreter lock 
issues that I haven't looked into much yet).

Compiling typelibs is not always necessary.  If the server is 
implemented with ORBit2, PyORBit can download the interface description 
from the server, so no typelib is necessary.  As for dynamic IDL 
loading, ORBit2 >= 2.5.0 has an extra libORBit-imodule library that can 
be used to parse IDL into interface descriptions.  I haven't wrapped 
this yet because I wanted to stay compatible with ORBit2 2.4.x, so that 
it would work in a GNOME 2.0 setup.  It will be added in a future 
release though.

I currently support marshalling and demarshalling of void, short, 
ushort, long, ulong, enum, float, double, boolean, char, octet, any, 
TypeCode, objref, exception, struct, union, string, sequence, array, 
longlong, ulonglong, wchar and wstring (as Python unicode strings) types.

Boolean types are converted to the Python True and False objects so with 
Python 2.3, they will print nicely.

Interface attributes are also exposed as object properties.  This was 
trivial to implement using new features found in Python 2.2.  It 
essentially does the equivalent of "foo = property(_get_foo, _set_foo)", 
without worrying about messy __getattr__/__setattr__ implementations.

Although PyORBit was designed for use with the gnome bindings, it should 
be generally useful.  I welcome bug reports, which can be sent to the 
pygtk list or me for now.  I should get around to adding a pyorbit 
product to bugzilla.gnome.org ...

The latest version of PyORBit can be found at:
    http://ftp.gnome.org/pub/GNOME/sources/pyorbit/1.99/

James.

-- 
Email: ja...@da...              | Linux.conf.au   http://linux.conf.au/
WWW:   http://www.daa.com.au/~james/ | Jan 22-25   Perth, Western Australia.