Re: Scripting in Gnome

On Thu, 2004-02-05 at 17:42, James Henstridge wrote:
> On 06/02/04 02:46, Bob Smith wrote:
> >Exactly. This was what I was talking about when I suggested making
> >GObject's self describing. a GObject could then be introspected by
> >CORBA, DBus, Python, Whatever to allow the scripting functionality
> >easily. I think GObject's properties are self describing currently but
> >methods are not. Anyone know what else would need to be described to
> >make this possible?
> >  
> >
> The ORBit2 IInterface IDL would be worth looking at for this kind of 
> thing.  You basically want:
>     * get the type of an object (we already have this with
>     * A way to find all base classes of a particular class (also already
>       available).
>     * A way to get a list of the methods of a class.
>     * For each method on the class:
>           o The return type
>           o List of argument names (you might consider this optional)
>           o List of argument types
>           o Whether each argument is in, out or inout.
>     * Require that all function arguments and return values can be
>       represented by the type system (this requires a fair bit of
>       work).  This might involve extending the type system.

Hmm... This would be a lot of work to program in all this information

I believe the GTK# project has a program that analyzes C files and
produces an XML description of the GObjects... If they do, maybe it
could be modified or an XSLT document be created to convert that
information to a form that can be automatically linked into a

>     * Some way to invoke a method on an instance programatically.
> The last one is probably most difficult.  The two ways to solve it are 
> to generate marshalling code (similar to what we do for signals), or use 
> something like libffi to construct the function calls (probably making 
> use of the interface information to help construct the call).

Yeah. Mono seems to be doing fairly well doing this sort of thing. Maybe
their team can provide a good solution to the problem.

> For GTK, we haven't really had to worry about this because C can already 
> call C functions quite easily :)  For CORBA, they needed to deal with 
> this from the start, since they needed to be able to convert invocations 
> from the network into function calls.
> Note that most of the language bindings for dynamic languages actually 
> implement most of this already.  Unfortunately, the format they expose 
> all the class information in is "Python classes" or "Perl classes", and 
> method calls are done using the "Python method call interface" or "Perl 
> method call interface" :)  This isn't very helpful if you are trying to 
> use the information from a language other than the one the binding is 
> for ...

Know how COM on Python works? Does it create proxy Python objects? We
could do the same thing...

> James.
Bob Smith <bob thestuff net>

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