RE: [gtk-list] Re: glib datalists question

["Verwerft, Marc" <MVerwerft nedcar nl>]

	On Tue, 9 Nov,  Havoc Pennington wrote:
	>On Tue, 9 Nov 1999, Marc Verwerft wrote:
	>> I have a question about glib datalists :
	>>     Why does 'g_datalist_id_set_data_full'  not accept items when
the
	>> datavalue is NULL or zero ?
	>> 
	>> I thought datalists had the same function as name/value pairs in
CORBA.
	>> Am I wrong ? Am I trying to 'abuse' datalists or is there another
	>> explanation ?
	>> 
	>
	>It looks to me like it will take a NULL value for the data as long
as your
	>destroy notify function is NULL. The reason is that "NULL value"
and
	>"unset" are equivalent (to set something to NULL, datalist just
deletes it
	>from the list; if you set something to NULL, it's the same as
removing
	>it). So you can't have a destroy func for something that's not in
the
	>datalist.
	>
	>Havoc

	No, it will never take a NULL value, not even when the destroy
notify function is NULL.
	I've made a small, but otherwise useless ;-}, program that shows the
behaviour.

	Is there another way to save a set of name/value pairs with NULL
values using glib ?


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/* * Testing of datalists */
#include <stdio.h>
#include <stdlib.h>
#include <glib.h>

struct _prop_st {
    char *id;
    gpointer val;
};

typedef struct _prop_st prop_st;

prop_st props[] = { {"first", (gpointer) 1},
                    {"second", (gpointer) 0},
                    {"third", (gpointer) 2},
                    {"fourth", (gpointer) 1000 },
                    {"fifth", (gpointer) 2000 },
                    {NULL, NULL}};

void print_vals(GQuark id, gpointer data, gpointer user_Data)
{
    printf("%s : %d\n", g_quark_to_string(id), (int) data);
}

int main(int argc, char *argv[])
{
    GData *dl;
    int i, j;
    g_datalist_init(&dl);
    for (i=0; props[i].id != NULL; i++) {
        quarks[i] = g_quark_from_string(props[i].id);
        g_datalist_id_set_data_full(&dl, quarks[i], props[i].val, NULL);
    }

    printf("---- 'foreach' iteration ----\n");
    g_datalist_foreach(&dl, print_vals, NULL);
    exit(0);
}      
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