GNOME library.

Gnome Developers' Information
Prev		Next

Chapter 5. GNOME library.

This chapter is intended to be a reference to the libgnome.

5.1. gnome-config

5.1.1. Author(s)

Miguel de Icaza <miguel@nuclecu.unam.mx>

5.1.2. Description

A set of routines for manipulating the database of configuration information.

5.1.3. Glossary

"config path" - a string that specifies which item to retrieve from the configuration database. For example, a config path of "/myapp/display_toolbox" could be used to retrieve the setting for whether 'myapp' should display its toolbox.
"default" - when retrieving a config item, specifies the value to be used if the item is not found.
"private configuration data" - Normally, config item data is located in files under the ~user/.gnome directory in a .ini-like format. These files are world-readable. Items that have security or privacy implications are stored and retrieved using the "private" versions of the gnome-config routines, and the data for these items is stored in files under the ~user/.gnome_private directory, which is not accessable by anyone except that user and the system administrator.
"translated" strings - GNOME's multilingual support means that multiple languages must be supported for configuration items. The gnome_config_*get_translated_string() and gnome_config_*set_translated_string() routines allow you to specify which language a string item should be accessed for.
"section" - a group of config items and other config sections

5.1.4. gnome_config_get_ - routines to retrieve information for a specified config path.

type
gnome_config_get_typename

(const char *path);

5.1.4.1. Description

Routine to retrieve a config item. 'typename' would be one of string, translated_string, int, bool, float, or vector. In the case of the gnome_config_get_string(), gnome_config_get_translated_string(), and gnome_config_get_vector(), ownership of the memory used by the returned value is given over to the application. When the application is done with it, it should be freed using g_free() or g_string_array_free() as appropriate.

Combinations of "private" and "with_default" versions of these routines exist. For example, there are gnome_config_get_string(), gnome_config_get_string_with_default() gnome_config_private_get_string(), and gnome_config_private_get_string_with_default() routines.

5.1.4.2. Usage

char *myitem;
gboolean is_default;

myitem =
gnome_config_get_string_with_default("/foo/blah=DefaultValue", &is_default);

5.1.4.3. Parameters

const char *path
The config path to the config item being accessed.
gboolean *def (gnome_config_get_*_with_default() routines only)
Address of a gboolean variable. Used to return an indication to the caller as to whether the return value is a default value or was retrieved from the config database for the specified 'path'.

5.1.5. gnome_config_set_* - routines to store information for a specified config path.

void
gnome_config_set_typename

(const char *path, type value);

5.1.5.1. Description>

Stores the specified value into the configuration database at the specified config path.

Note that there are "private" variations on all the regular routines, e.g. gnome_config_set_string() and gnome_config_private_set_string().

5.1.5.2. Usage

char *values[] = {"A one", "a two", "a three"};

gnome_config_set_vector("/foo/bar/baz", 3, values);

5.1.6. gnome_config_has_section - Checks whether a config section exists

gboolean
gnome_config_has_section

(const char *path);

5.1.6.1. Description

This routine returns TRUE if the specified section/item exists, xor FALSE if it does not.

A parallel gnome_config_private_has_section() routine also is available.

5.1.6.2. Usage

if(gnome_config_has_section("/foo/bar/baz")) {
        g_print("You have saved preferences.\n");
} else {
        g_print("You haven't saved preferences yet.\n");
}

5.1.6.3. Parameters

const char *path
Config path of the item/section of interest

5.1.7. gnome_config_init_iterator - Setup an iterator to get a listing of items in a specified config section.

 void
*gnome_config_init_iterator

(const char *path);

5.1.8. gnome_config_init_iterator - Setup an iterator to get a listing of sections in a specified config section.

 void
*gnome_config_init_iterator_sections

(const char *path);

5.1.8.1. Description

This routine is used to begin a loop over all the items in a config section. gnome_config_iterator_next() is used to advance to the next item.

Note that a gnome_config_private_init_iterator_sections() variant exists.

5.1.8.2. Usage

See the gnome_config_iterator_next() usage example

5.1.8.3. Parameters

const char *path
Config section to list the sub-sections of.

5.1.9. gnome_config_iterator_next - get the next item from an iterator

void
*gnome_config_iterator_next

(void *s, char **key, char **value);

5.1.9.1. Description

This function normally serves as the loop update for a config item or section iterator. The return value is an opaque pointer needed by gnome_config_iterator_next, or NULL if there are no more available data in the iterator.

5.1.9.2. Usage

char *section_name, *key, *value;
void *section_iter, *item_iter;
GString *tmpstr;
tmpstr = g_string_new(NULL);
for(section_iter = gnome_config_init_iterator_sections("/foo");
    section_iter != NULL;
    section_iter = gnome_config_iterator_next(section_iter, NULL, &section_name)) {
    
    g_string_sprintf(tmpstr, "/foo/%s", section_name);
    
    for(item_iter = gnome_config_init_iterator(tmpstr->str);
        item_iter;
        item_iter = gnome_config_iterator_next(item_iter, &key, &value)) {
        g_print("Got key %s -> value %s in section %s of /foo\n",
                key, value, section_name);

        g_free(key); g_free(value);
    }

    g_free(section_name);
}
g_string_free(tmpstr);

5.1.9.3. Parameters

void *s
A value returned by either gnome_config_*_init_iterator_*() or gnome_config_iterator_next().
char **key
The address of a char * variable. Used to return a pointer to the key for item iterators. For section iterators, this should be NULL.
char **value
The address of a char * variable. Used to return a pointer to the value for item iterators, or to the section name for section iterators.

5.1.10. gnome_config_drop_all - drops all the cached config data from the in-memory cache

void gnome_config_drop_all(void);

5.1.10.1. Description

The gnome_config routines cache the configuration entries in memory to increase speed. Calling gnome_config_drop_all() causes the cache to be cleared.

5.1.11. gnome_config_sync - writes all unwritten config entries to the config database

void gnome_config_sync(void);

5.1.11.1. Description

As previously stated, the gnome_config routines cache configuration entries in memory to increase speed. This routine flushes the cache to disk - you would ordinarily use it after a number of gnome_config_set_* operations.

5.1.12. gnome_config_clean_ - routines for removing a configuration database entry or subtree altogether

void gnome_config_clean_file(const char *path);

void gnome_config_private_clean_file(const char *path);

void gnome_config_clean_section(const char *path);

void gnome_config_private_clean_section(const char *path);

void gnome_config_clean_key(const char *path);

void gnome_config_private_clean_key(const char *path);

5.1.12.1. Description

These routines delete all the configuration entries associated with the specified entity (either a file, section, or key).

5.1.12.2. Usage

char *val1, *val2;

gnome_config_set_string("/foo/bar", "baz");
val1 = gnome_config_get_string("/foo/bar");
gnome_config_clean_section("/foo");
val2 = gnome_config_get_string("/foo/bar");
if(val1 && val2 && !strcmp(val1, val2)) {
    g_error("The values match! gnome_config_clean_section is broken!");
} else {
    g_message("gnome_config_clean_section worked.");
}

5.1.12.3. Parameters

const char *path
The config path to the config item which is to be removed.

5.1.13. gnome_config_*get_real_path

char *gnome_config_get_real_path(const char *path);

char *gnome_config_private_get_real_path(const char *path);

5.1.13.1. Description

Occasionally an application writer may want to get the local filename where a config item is stored. When passed a config path, these routines (currently implemented as macros) return that filename.

5.1.13.2. Usage

char *filename = gnome_config_get_real_path("/foo/bar");
FILE *filehandle = fopen(filename, "w");
/* do devious things with the file */

5.1.13.3. Parameters

const char *path
The config path to the config item being accessed.

Prev	Home	Next
Architecture notes.		gnome-defs