Many thanks! Fwd: Re: Request for pointers/hints for processing container arguments ...

[rony]

Hi there,

sorry for not noticing that the reply-to would not direct my thanks via
the dbus-list, which I would like very much, giving the great help Mike
Gorse has given! Kudos to Mike!

---rony


-------- Original Message --------
Subject: 	Re: Request for pointers/hints for processing container
arguments ...
Date: 	Tue, 21 Jun 2011 21:52:07 +0200
From: 	rony <rony at wu.ac.at>
Organization: 	WU Wien
To: 	Mike Gorse <mgorse at novell.com>



Mike:

super, thank you *very, very* much for your kind explanations, they
really help a *lot* !

This is more than enough "food for thoughts" helping really a lot to go
more systematically over the documentation once more!
(Your DBUS_TYPE_DICT example is really just extremely instructional!)

Best regards,

---rony



On 21.06.2011 20:42, Mike Gorse wrote:
> Hi Rony,
>
> Basically you can use dbus_message_iter_open_container and
> dbus_message_iter_close_container to write structs/dicts/arrays and
> dbus_message_iter_recurse to read them.  Dictionaries have a
> DBUS_TYPE_DICT (which wants a type that should look something like
> {ss}) containing entries (which want a type of NULL).  To write a
> struct, you can use something like
>
> dbus_message_iter_open_container (&iter, DBUS_TYPE_STRUCT, NULL,
> &iter_struct);
> // use dbus_message_iter_append_basic on iter_struct to write your data
> dbus_message_iter_close_container (&iter, &iter_struct);
>
> where "iter" is a DBusMessageIter that you've initialized.  For a
> dictionary with strings for the key and value, you'd have something like
>
> dbus_message_iter_open_container (&iter, DBUS_TYPE_DICT< "{ss}",
> &iter_dict);
> while (more_entries_to_write) {
>   dbus_message_iter_open_container (&iter_dict, DBUS_TYPE_DICT_ENTRY,
> NULL, &iter_dict_entry);
>   dbus_message_iter_append_basic (&iter_dict_entry, DBUS_TYPE_STRING,
> &key);
>   dbus_message_iter_append_basic (&iter_dict_entry, DBUS_TYPE_STRING,
> &val);
>   dbus_message_iter_close_container (&iter_dict, &iter_dict_entry);
> }
> dbus_message_iter_close_container (&iter, &iter_dict);
>
> Arrays can be handled similarly and want a type argument (ie, "i" for
> integers), but they can also be handled with the functions you
> mentioned. Variants are similar and also want the type to be specified
> when opening the container.
>
> Also, these functions have return values to return errors if they run
> out of memory.
>
> Hth,
> -Mike
>
> On Tue, 21 Jun 2011, rony wrote:
>
>> Hi there,
>>
>> my name is Rony and I have started to write a language binding for a
>> scripting language named ooRexx (http://www.ooRexx.org). Hence, despite
>> all well-meant warnings, I have to delve into the C bindings in order to
>> successfully create the binding (starting out for Linux, but aiming also
>> on porting later to MacOSX and Windows).
>>
>> In the process of doing so I have studied the specs, tutorials and
>> Matthew Johnsons's *great tutorail* (however, the link on
>> <http://www.freedesktop.org/wiki/Software/dbus> to his tutorial at
>> <http://dbus.freedesktop.org/doc/dbus/libdbus-tutorial.html> is dead,
>> but I managed to get a version on his web site), which has helped me
>> a lot.
>>
>> Currently I am involved in writng the code for processing the ooRexx
>> arguments for DBus which now work for all simple types (using
>> dbus_message_iter_append_basic(...)).
>>
>> The next step is to deal with the container types variant, arrays,
>> structs and dicts. While studying the specification and the methods in
>> DBusMessage (like dbus_message_iter_get_array_len(*iter) or
>> dbus_message_iter_get_fixed_array(*iter, void *value, int *n_elements),
>> but also dbus_message_iter_append_fixed_array(*iter, int element_type,
>> const void *value, int n_elements) etc.) it is the case that I still am
>> not able to understand how exactly these types have to be processed.
>>
>> Any little program/snippet or pseudo code would help me a lot and hence
>> turning to this list of experts to ask for help!
>>
>> If you have pointers to any plain C code (glib's binding won't help me
>> unfortunately) or would be kind enough to simply sketch in scarce
>> pseudocode how to create those container values for message arguments, I
>> would *really* appreciate it a lot!
>>
>> TIA,
>>
>> ---rony
>>
>> P.S.: If anyone has anything comparable to Matthew Johnson's tutorial,
>> but demoing how to process container values, that would be a boon!
>>
>>
>> _______________________________________________
>> dbus mailing list
>> dbus at lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/dbus
>>


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