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I played a little with GConf today. Here's some little introduction to it.

We'll be doing 3 very simple things today:

1. Read out GConf key values


2. Set key values


3. Read out values, and register to value changes

Reading out a string from the GConf tree

Reading out a value (in our case a string) is very simple: first of all you need to know which string you want to read. In this sample we'll try to get the value of the default browser. Then you create a GConfClient, a proxy to the GConf system, you query gconfd using the proxy, get the value and do something with it.

Here's the code:

/* GConf test reader
 * Compile using
 *      gcc `pkg-config --libs --cflags gconf-2.0` -o reader reader.c
 */

#include <glib.h>
#include <gconf/gconf-client.h>

/* Path to the key we'll be working with */
#define GCKEY "/desktop/gnome/applications/browser/exec"

gint main(gint argc, gchar *argv[]) {
        /* Our proxy */
        GConfClient *gclient = NULL;
        /* String to store the GCKEY's value in */
        gchar *val = NULL;

        /* Initialize the GConf subsystem */
        gconf_init(argc, argv, NULL);

        g_print("Working with key \"%s\"\n", "" GCKEY);
        
        /* Get the default GConf proxy */
        gclient = gconf_client_get_default();
        g_assert(gclient != NULL);

        /* Get the value of GCKEY */
        val = gconf_client_get_string(gclient, "" GCKEY, NULL);
        if(val == NULL) {
                /* Key was not set before */
                val = g_strdup("<unset>");
        }
        g_assert(val != NULL);

        g_print("Value: \"%s\"\n", val);

        g_free(val);

        return 0;
}

As you can see this is very straight-forward.
Now compile and run the code:

ikke@marslander ~/Projects/gconf $ gcc `pkg-config --libs --cflags gconf-2.0` -o reader reader.c
ikke@marslander ~/Projects/gconf $ ./reader
Working with key "/desktop/gnome/applications/browser/exec"
Value: "mozilla"

Setting a key value

To set a key, once more we just need a GConfClient proxy, and call a function to set the new key value:

/* GConf test writer
 * Compile using
 *      gcc `pkg-config --libs --cflags gconf-2.0` -o setkey setkey.c
 */

#include <glib.h>
#include <gconf/gconf-client.h>

/* Path to the key we'll be working with */
#define GCKEY "/extra/test/key"

gint main(gint argc, gchar *argv[]) {
        /* Our proxy */
        GConfClient *gclient = NULL;
        /* New value */
        gchar *val = NULL;

        /* Initialize the GConf subsystem */
        gconf_init(argc, argv, NULL);

        if(argc > 1) {
                val = g_strdup(argv[1]);
        }
        else {
                val = g_strdup("testval");
        }

        g_print("Working with key \"%s\"\n", "" GCKEY);
        
        /* Get the default GConf proxy */
        gclient = gconf_client_get_default();
        g_assert(gclient != NULL);

        g_assert(val != NULL);
        gconf_client_set_string(gclient, "" GCKEY, val, NULL);

        g_print("Value \"%s\" set\n", val);

        g_free(val);

        return 0;
}

Again, compile the code and play around with it:

ikke@marslander ~/Projects/gconf $ gcc `pkg-config --libs --cflags gconf-2.0` -o setkey setkey.c
ikke@marslander ~/Projects/gconf $ ./setkey
Working with key "/extra/test/key"
Value "testval" set
ikke@marslander ~/Projects/gconf $ ./setkey test2
Working with key "/extra/test/key"
Value "test2" set

Now you might want to alter reader.c and compile it again so it reads out this new key instead of the one we used before.

Using change notifications

At last we'll be using one of the more advanced features of GConf, change notifications. This means we can register a callback to a key change, so when the key's value is changed (in-process or by another process) we'll be notified of this.
One again this is very easy: get a GConfClient proxy, figure out to which key you want to subscribe, find out the container directory, tell gconfd you want to register to that "directory", add a key change event handler, and you're done. This might sound confusing, read the code sample to see how easy it is.

/* GConf test listener
 * Compile using
 *      gcc `pkg-config --libs --cflags gconf-2.0` -o listener listener.c
 */

#include <glib.h>
#include <gconf/gconf-client.h>

/* The GConf PATH we'll want to monitor */
#define GCPATH "/extra/test"
/* Path to the key we'll be working with */
#define GCKEY "/extra/test/key"

/* This is the callback function for GCKEY changes */
void key_changed_cb(GConfClient* client, guint cnxn_id, GConfEntry *entry, gpointer user_data) {
        /* Store the new key value */
        gchar *val = NULL;
        /* A local GConfValue */
        GConfValue *value = NULL;

        /* Get the value from the provided entry */
        value = gconf_entry_get_value(entry);
        
        /* This should not happen, but one never knows */
        if(value == NULL) {
                val = g_strdup("<unset>");
        }
        else {
                /* Check value type, we want a string */
                if(value->type == GCONF_VALUE_STRING) {
                        /* Get the key value
                         * We use g_strdup because we'll g_free(val) later */
                        val = g_strdup(gconf_value_get_string(value));
                }
                else {
                        val = g_strdup("<wrong type>");
                }
        }
        g_assert(val != NULL);

        g_print("Value changed: \"%s\"\n", val);

        g_free(val);
}

gint main(gint argc, gchar *argv[]) {
        /* Our proxy */
        GConfClient *gclient = NULL;
        /* String to store the GCKEY's value in */
        gchar *val = NULL;
        /* A simple mainloop */
        GMainLoop *loop = NULL;

        /* Initialize the GConf subsystem */
        gconf_init(argc, argv, NULL);

        g_print("Working with key \"%s\"\n", "" GCKEY);
        
        /* Get the default GConf proxy */
        gclient = gconf_client_get_default();
        g_assert(gclient != NULL);

        /* Get the value of GCKEY */
        val = gconf_client_get_string(gclient, "" GCKEY, NULL);
        if(val == NULL) {
                /* Key was not set before */
                val = g_strdup("<unset>");
        }
        g_assert(val != NULL);

        g_print("Initial value: \"%s\"\n", val);

        g_free(val);

        /* Watch GCPATH */
        gconf_client_add_dir(gclient, "" GCPATH, GCONF_CLIENT_PRELOAD_NONE, NULL);
        /* And specify a callback function for GCKEY changes */
        gconf_client_notify_add(gclient, "" GCKEY, key_changed_cb, NULL, NULL, NULL);

        /* Create a mainloop and run it */
        loop = g_main_loop_new(NULL, FALSE);
        g_assert(loop != NULL);
        g_main_loop_run(loop);

        return 0;
}

50% of this code is equal to "reader.c". The only "special" things is adding a callback notifier in main(), and the callback function itself.
You should notice GConfValues got a type: in this sample we check whether the key's type equals to "GCONF_VALUE_STRING", otherwise we don't "process" the value.

Once more, compile and run this code:

ikke@marslander ~/Projects/gconf $ gcc `pkg-config --libs --cflags gconf-2.0` -o listener listener.c
ikke@marslander ~/Projects/gconf $ ./listener
Working with key "/extra/test/key"
Initial value: "test2"

At this point, the program just hangs due to our GMainLoop. The key value is the one last set with ./setkey

Now open a new console, go to the directory where setkey is located, and execute it giving some new value. Then watch what's going on at the terminal where "listener" is running:

ikke@marslander ~/Projects/gconf $ ./setkey "a longer test key"
Working with key "/extra/test/key"
Value "a longer test key" set

In the "listener" console, we see this:

Value changed: "a longer test key"

Jay, change notifications working fine :-)

In this sample we only worked with string values, GConf also supports floats, integers, booleans, lists and even more. Check out the API docs for more information.
If you want to read more about GConf, e.g. its internals, you might want to check this tutorial by the GConf author, Havoc Pennington. Notice this is an old document, so the code samples in there won't work anymore, the GConf API has changed quite a lot since then. The ideas explained in the article are still relevant though, so it's worth reading.

The Quartier Latin is an area in the Ville-Marie borough of Montreal, surrounding UQAM and lower Saint-Denis Street, between downtown and the Village gai. It is known for its theatres, artistic atmosphere, cafés, and boutiques.

It owes its name, a reference to the Quartier Latin in Paris, to the presence of the nascent Université de Montréal in the 1920s. In the 1940s the university moved out and headed for a new campus on the north slopes of Mount Royal, far from the downtown borough. In the late 1960s UQAM was born and established itself in the Ville-Marie borough, giving a modern underpinning to the name. A large junior college, the CEGEP du Vieux-Montreal also moved in at about the same period.

The Grande Bibliothèque du Québec joined these educational institutions in 2005.

Arcosanti is an experimental town that is being built in central Arizona, 70 miles (110 km) outside of Phoenix. Paolo Soleri, using a concept he calls arcology (architecture + ecology), designed the town to demonstrate ways urban conditions could be improved while minimizing the destructive impact on the earth.

Arcosanti is being built on only 25 acres (0.1 km²) of a 4060 acre (16 km²) land preserve, keeping its inhabitants near the natural countryside. The Arcosanti web site describes how an arcology functions in Arcosanti: "The built and the living interact as organs would in a highly evolved being. Many systems work together, with efficient circulation of people and resources, multi-use buildings, and solar orientation for lighting, heating and cooling."

As of 2005 Arcosanti stands some fraction of 1% complete. Existing structures include a three-story visitors' center / cafe / gift shop, the bronze-casting apse (half-dome) carefully situated to accept maximal winter sun and minimal summer sun, two large barrel vaults, a ring of apartment residences around an outdoor amphitheatre, a community swimming pool, and Soleri's suite. A two-bedroom 'Sky Suite' occupies the highest point in the complex and is available for overnight guests.

In Arcosanti, apartments, businesses, production, technology, open space, studios, and educational and cultural events are all accessible, while privacy is paramount in the overall design. Solar greenhouses are planned to provide gardening space for public and private use, and act as solar collectors for winter heat.

The city serves as an educational complex where workshops and classes are offered. Students from around the world are constructing Arcosanti. In addition, about 50,000 tourists visit Arcosanti each year.

Funds to build Arcosanti are raised through the sale of art objects, the most famous being cast wind chimes. More funds are raised from workshop tuitions, which people ("workshoppers") pay for a five week hands-on experience. The workshops are the principal means by which Arcosanti is constructed.

External links

• The Arcosanti Web Site
• The Arcosanti Work Song (c)1972
• Sky Suite guest review

Ik ben kapot XX(

De voorbije twee nachten maar een paar uurtjes geslapen. Ik moet er echt veel te vroeg uit, om 6u, maar kan echt niet in slaap geraken zo vroeg, ook al ben ik doodmoe, ik word gewoonweg terug wakker en actief 's avonds. Vannacht bijna helemaal niet geslapen: veel te laat gegeten door omstandigheden (en dan nog wel frieten met mosselen, uitermate zwaar), veel te warm en irritante muggen. Ik moest er toch weer om 6u uit en ben vandaag maar om 21u terug thuisgekomen: heel de dag gewerkt (en vooral gewacht) in de Thalys. Gelukkig moet ik morgen maar om 9u45 in Brussel-Zuid zijn, kan ik toch weer wat langer slapen: ongeveer een half uurtje treinen van hieruit in plaats van de normale 1u30 naar Wolfstee.

Deep End was a short-lived supergroup founded by guitarist Pete Townshend of The Who and featuring David Gilmour of Pink Floyd. The group also included bassist Chucho Merchan, percussionist Jody Linscott, keyboardist John 'Rabbit' Bundrick, backing vocalists Billy Nicholls, Cleveland Watkiss, and Chyna, and a five-piece brass ensemble called The Kickhorns. The group performed two 1995 charity concerts at London's Brixton Academy (a third was cancelled due to poor ticket sales), which were later released as the album Deep End Live!; a concert at the MIDEM trade fair in France, and appeared on The Tube.

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