GConfValue, GConfEntry, GConfMetaInfo

GConfValue, GConfEntry, GConfMetaInfo — A GConfValue stores a dynamically-typed value. A GConfEntry stores a key-value pair. A GConfMetaInfo stores metainformation about a key.

Synopsis

enum                GConfValueType;
                    GConfValue;
#define             GCONF_VALUE_TYPE_VALID              (x)
const char*         gconf_value_get_string              (const GConfValue *value);
int                 gconf_value_get_int                 (const GConfValue *value);
double              gconf_value_get_float               (const GConfValue *value);
GConfValueType      gconf_value_get_list_type           (const GConfValue *value);
GSList*             gconf_value_get_list                (const GConfValue *value);
GConfValue*         gconf_value_get_car                 (const GConfValue *value);
GConfValue*         gconf_value_get_cdr                 (const GConfValue *value);
gboolean            gconf_value_get_bool                (const GConfValue *value);
GConfSchema*        gconf_value_get_schema              (const GConfValue *value);
GConfValue*         gconf_value_new                     (GConfValueType type);
GConfValue*         gconf_value_new_from_string         (GConfValueType type,
                                                         const gchar *str,
                                                         GError **err);
GConfValue*         gconf_value_copy                    (const GConfValue *src);
void                gconf_value_free                    (GConfValue *value);
void                gconf_value_set_int                 (GConfValue *value,
                                                         gint the_int);
void                gconf_value_set_string              (GConfValue *value,
                                                         const gchar *the_str);
void                gconf_value_set_float               (GConfValue *value,
                                                         gdouble the_float);
void                gconf_value_set_bool                (GConfValue *value,
                                                         gboolean the_bool);
void                gconf_value_set_schema              (GConfValue *value,
                                                         const GConfSchema *sc);
void                gconf_value_set_schema_nocopy       (GConfValue *value,
                                                         GConfSchema *sc);
void                gconf_value_set_car                 (GConfValue *value,
                                                         const GConfValue *car);
void                gconf_value_set_car_nocopy          (GConfValue *value,
                                                         GConfValue *car);
void                gconf_value_set_cdr                 (GConfValue *value,
                                                         const GConfValue *cdr);
void                gconf_value_set_cdr_nocopy          (GConfValue *value,
                                                         GConfValue *cdr);
void                gconf_value_set_list_type           (GConfValue *value,
                                                         GConfValueType type);
void                gconf_value_set_list_nocopy         (GConfValue *value,
                                                         GSList *list);
void                gconf_value_set_list                (GConfValue *value,
                                                         GSList *list);
gchar*              gconf_value_to_string               (const GConfValue *value);
                    GConfMetaInfo;
GConfMetaInfo*      gconf_meta_info_new                 (void);
void                gconf_meta_info_free                (GConfMetaInfo *gcmi);
const char*         gconf_meta_info_get_schema          (GConfMetaInfo *gcmi);
const char*         gconf_meta_info_get_mod_user        (GConfMetaInfo *gcmi);
GTime               gconf_meta_info_mod_time            (GConfMetaInfo *gcmi);
void                gconf_meta_info_set_schema          (GConfMetaInfo *gcmi,
                                                         const gchar *schema_name);
void                gconf_meta_info_set_mod_user        (GConfMetaInfo *gcmi,
                                                         const gchar *mod_user);
void                gconf_meta_info_set_mod_time        (GConfMetaInfo *gcmi,
                                                         GTime mod_time);
                    GConfEntry;
const char*         gconf_entry_get_key                 (const GConfEntry *entry);
GConfValue*         gconf_entry_get_value               (const GConfEntry *entry);
const char*         gconf_entry_get_schema_name         (const GConfEntry *entry);
gboolean            gconf_entry_get_is_default          (const GConfEntry *entry);
gboolean            gconf_entry_get_is_writable         (const GConfEntry *entry);
GConfEntry*         gconf_entry_new                     (const gchar *key,
                                                         const GConfValue *val);
GConfEntry*         gconf_entry_new_nocopy              (gchar *key,
                                                         GConfValue *val);
GConfEntry*         gconf_entry_copy                    (const GConfEntry *src);
void                gconf_entry_free                    (GConfEntry *entry);
void                gconf_entry_ref                     (GConfEntry *entry);
void                gconf_entry_unref                   (GConfEntry *entry);
GConfValue*         gconf_entry_steal_value             (GConfEntry *entry);
void                gconf_entry_set_value               (GConfEntry *entry,
                                                         const GConfValue *val);
void                gconf_entry_set_value_nocopy        (GConfEntry *entry,
                                                         GConfValue *val);
void                gconf_entry_set_schema_name         (GConfEntry *entry,
                                                         const gchar *name);
void                gconf_entry_set_is_default          (GConfEntry *entry,
                                                         gboolean is_default);
void                gconf_entry_set_is_writable         (GConfEntry *entry,
                                                         gboolean is_writable);

Description

GConfValue stores one of the value types GConf understands; GConf uses GConfValue to pass values around because it doesn't know the type of its values at compile time.

A GConfEntry pairs a relative key name with a value, for example if the value "10" is stored at the key "/foo/bar/baz", the GConfEntry will store "baz" and "10".

A GConfMetaInfo object holds metainformation about a key, such as its last modification time and the name of the schema associated with it. You should rarely if ever need to use GConfMetaInfo. (In fact you can't get the metainfo for a key using the current API.)

Details

enum GConfValueType

typedef enum {
  GCONF_VALUE_INVALID,
  GCONF_VALUE_STRING,
  GCONF_VALUE_INT,
  GCONF_VALUE_FLOAT,
  GCONF_VALUE_BOOL,
  GCONF_VALUE_SCHEMA,

  /* unfortunately these aren't really types; we want list_of_string,
     list_of_int, etc.  but it's just too complicated to implement.
     instead we'll complain in various places if you do something
     moronic like mix types in a list or treat pair<string,int> and
     pair<float,bool> as the same type. */
  GCONF_VALUE_LIST,
  GCONF_VALUE_PAIR
  
} GConfValueType;

Used to indicate the type of a GConfValue.

GCONF_VALUE_INVALID Never the type of a GConfValue obtained from GConf functions; used to indicate errors and the like.
GCONF_VALUE_STRING String value (gchar*).
GCONF_VALUE_INT Integer value (gint).
GCONF_VALUE_FLOAT Floating point value (gdouble).
GCONF_VALUE_BOOL Boolean value (gboolean).
GCONF_VALUE_SCHEMA Schema value (GConfSchema).
GCONF_VALUE_LIST List of GConfValue; GConfValue elements must have a primitive type (i.e. they may not be lists or pairs), and all elements of a list must have the same type.
GCONF_VALUE_PAIR Pair of GConfValue; the first field (car) and the second field (cdr) may have different types. The two elements of a pair must be primitive types, not lists or pairs.

GConfValue

typedef struct {
  GConfValueType type;
} GConfValue;

Represents a dynamically-typed value. The type field tells you the type of the value; the other fields should be accessed with the accessor functions and macros.

A GConfValue should always be initialized before use. That is, you should not use a GConfValue unless you have called one of the functions beginning with "gconf_value_set_".. For lists, initialization has two steps: first you must set the list element type, then you must set the list value.

GConfValueType type; The GConfValueType of this GConfValue. The only field of GConfValue you should access directly.

GCONF_VALUE_TYPE_VALID()

#define GCONF_VALUE_TYPE_VALID(x) (((x) > GCONF_VALUE_INVALID) && ((x) <= GCONF_VALUE_PAIR))

x :

gconf_value_get_string ()

const char*         gconf_value_get_string              (const GConfValue *value);

Returns a const gchar* for a GConfValue with type GCONF_VALUE_STRING. The returned string is not a copy, don't try to free it. It is "owned" by the GConfValue and will be destroyed when the GConfValue is destroyed.

If the GConfValue is not initialized (i.e. no one has called gconf_value_set_string()) then the string may be NULL, but of course you should not try to use an uninitialized GConfValue.

value : a GConfValue.
Returns : a const char*.

gconf_value_get_int ()

int                 gconf_value_get_int                 (const GConfValue *value);

Returns a gint for a GConfValue with type GCONF_VALUE_INT.

value : a GConfValue.
Returns : a gint.

gconf_value_get_float ()

double              gconf_value_get_float               (const GConfValue *value);

Returns a gdouble for a GConfValue with type GCONF_VALUE_FLOAT.

value : a GConfValue.
Returns : a gdouble.

gconf_value_get_list_type ()

GConfValueType      gconf_value_get_list_type           (const GConfValue *value);

Returns the type of the list elements in a GConfValue with type GCONF_VALUE_LIST.

value : a GConfValue.
Returns : the type of the list elements (a primitive type).

gconf_value_get_list ()

GSList*             gconf_value_get_list                (const GConfValue *value);

Returns a GSList containing GConfValue objects. Each GConfValue in the returned list will have the type returned by gconf_value_get_list_type(). Remember that the empty GSList is equal to NULL. The list is not a copy; it is "owned" by the GConfValue and will be destroyed when the GConfValue is destroyed.

value : a GConfValue.
Returns : a GList.

gconf_value_get_car ()

GConfValue*         gconf_value_get_car                 (const GConfValue *value);

Returns the first member (car) of a GConfValue with type GCONF_VALUE_PAIR. The car is another GConfValue, with a primitive type (bool, int, float, string, schema).

The returned value is not a copy; it is "owned" by the pair and will be destroyed when the pair is destroyed.

value : a GConfValue.
Returns : the first member of a pair, a primitive type.

gconf_value_get_cdr ()

GConfValue*         gconf_value_get_cdr                 (const GConfValue *value);

Returns the second member (cdr) of a GConfValue with type GCONF_VALUE_PAIR. The cdr is another GConfValue, with a primitive type (bool, int, float, string, schema).

The returned value is not a copy; it is "owned" by the pair and will be destroyed when the pair is destroyed.

value : a GConfValue.
Returns : the second member of a pair, a primitive type.

gconf_value_get_bool ()

gboolean            gconf_value_get_bool                (const GConfValue *value);

Returns a gboolean for a GConfValue with type GCONF_VALUE_BOOL.

value : a GConfValue.
Returns : a gboolean value.

gconf_value_get_schema ()

GConfSchema*        gconf_value_get_schema              (const GConfValue *value);

Returns a GConfSchema for a GConfValue with type GCONF_VALUE_SCHEMA. If the GConfValue is uninitialized, it may return NULL; but of course you should have initialized the GConfValue. The GConf library will not return values with a NULL schema.

The returned value is not a copy; it is "owned" by the GConfValue and will be destroyed when the GConfValue is destroyed.

value : a GConfValue.
Returns : a GConfSchema.

gconf_value_new ()

GConfValue*         gconf_value_new                     (GConfValueType type);

Creates a new GConfValue with type type. The type is immutable after creation; values have a fixed type. You must initialize the GConfValue after creation; that is, you must set its value with one of the "setter" functions.

type : type of the new GConfValue.
Returns : newly-allocated GConfValue.

gconf_value_new_from_string ()

GConfValue*         gconf_value_new_from_string         (GConfValueType type,
                                                         const gchar *str,
                                                         GError **err);

Creates a new GConfValue with type type and value set to the string passed. Based on the value of type, this function does the appropriate conversion of the string passed to the type, does error checks to ensure the value is valid, and then calls the appropriate gconf_set function depending on the type to set the value.

type : type of the new GConfValue.
str : the return location for an allocated GError, or NULL to ignore errors.
err : the value to be set.
Returns : the value to be set.

gconf_value_copy ()

GConfValue*         gconf_value_copy                    (const GConfValue *src);

Copies a GConfValue. The copy is a deep copy, that is, any allocated memory inside the GConfValue will also be copied.

src : a GConfValue to copy.
Returns : a newly-allocated GConfValue identical to src.

gconf_value_free ()

void                gconf_value_free                    (GConfValue *value);

Deallocates a GConfValue. Also deallocates any allocated memory inside the GConfValue (such as lists, pair members, strings, and schemas).

value : a GConfValue to destroy.

gconf_value_set_int ()

void                gconf_value_set_int                 (GConfValue *value,
                                                         gint the_int);

Sets the value of a GConfValue with type GCONF_VALUE_INT.

value : a GConfValue of type GCONF_VALUE_INT.
the_int : the integer.

gconf_value_set_string ()

void                gconf_value_set_string              (GConfValue *value,
                                                         const gchar *the_str);

Sets the value of a GConfValue with type GCONF_VALUE_STRING. the_str is copied.

value : a GConfValue of type GCONF_VALUE_STRING.
the_str : the string.

gconf_value_set_float ()

void                gconf_value_set_float               (GConfValue *value,
                                                         gdouble the_float);

Sets the value of a GConfValue with type GCONF_VALUE_FLOAT.

value : a GConfValue of type GCONF_VALUE_FLOAT.
the_float : the floating point number.

gconf_value_set_bool ()

void                gconf_value_set_bool                (GConfValue *value,
                                                         gboolean the_bool);

Sets the value of a GConfValue with type GCONF_VALUE_BOOL.

value : a GConfValue of type GCONF_VALUE_BOOL.
the_bool : a boolean value (TRUE or FALSE).

gconf_value_set_schema ()

void                gconf_value_set_schema              (GConfValue *value,
                                                         const GConfSchema *sc);

Sets the value of a GConfValue with type GCONF_VALUE_SCHEMA. The GConfSchema is copied. Alternatively you can use gconf_value_set_schema_nocopy().

value : a GConfValue with type GCONF_VALUE_SCHEMA.
sc : the GConfSchema.

gconf_value_set_schema_nocopy ()

void                gconf_value_set_schema_nocopy       (GConfValue *value,
                                                         GConfSchema *sc);

Sets the value of a GConfValue with type GCONF_VALUE_SCHEMA. The GConfSchema is not copied; the GConfValue takes ownership of it, and it should only be accessed via the gconf_value_get_schema() macro. This function is provided as a more efficient version of gconf_value_set_schema().

value : a GConfValue with type GCONF_VALUE_SCHEMA.
sc : the GConfSchema.

gconf_value_set_car ()

void                gconf_value_set_car                 (GConfValue *value,
                                                         const GConfValue *car);

Sets the value of the first field (car) of a GConfValue with type GCONF_VALUE_PAIR. The GConfValue is copied. Alternatively, use gconf_value_set_car_nocopy().

value : a GConfValue with type GCONF_VALUE_PAIR.
car : the GConfValue to set as the car of the pair.

gconf_value_set_car_nocopy ()

void                gconf_value_set_car_nocopy          (GConfValue *value,
                                                         GConfValue *car);

Sets the value of the first field (car) of a GConfValue with type GCONF_VALUE_PAIR. The GConfValue is not copied; the GConfValue takes ownership of it. Alternatively, use gconf_value_set_car().

value : a GConfValue with type GCONF_VALUE_PAIR.
car : the GConfValue to set as the car of the pair.

gconf_value_set_cdr ()

void                gconf_value_set_cdr                 (GConfValue *value,
                                                         const GConfValue *cdr);

Sets the value of the second field (cdr) of a GConfValue with type GCONF_VALUE_PAIR. The GConfValue is copied. Alternatively, use gconf_value_set_cdr_nocopy().

value : a GConfValue with type GCONF_VALUE_PAIR.
cdr : the GConfValue to set as the cdr of the pair.

gconf_value_set_cdr_nocopy ()

void                gconf_value_set_cdr_nocopy          (GConfValue *value,
                                                         GConfValue *cdr);

Sets the value of the second field (cdr) of a GConfValue with type GCONF_VALUE_PAIR. The GConfValue is not copied; the GConfValue takes ownership of it. Alternatively, use gconf_value_set_cdr().

value : a GConfValue with type GCONF_VALUE_PAIR.
cdr : the GConfValue to set as the cdr of the pair.

gconf_value_set_list_type ()

void                gconf_value_set_list_type           (GConfValue *value,
                                                         GConfValueType type);

Sets the type of the elements in a GConfValue of type GCONF_VALUE_LIST. All the elements in the list must have the same type. You must set the list type before you can set the list value.

value : a GConfValue with type GCONF_VALUE_LIST.
type : the type of elements in this list.

gconf_value_set_list_nocopy ()

void                gconf_value_set_list_nocopy         (GConfValue *value,
                                                         GSList *list);

Sets the value of a GConfValue with type GCONF_VALUE_LIST. The list argument should be a GSList of GConfValue. Each GConfValue in the list must have the same type, and this type must be specified in advance with gconf_value_set_list_type(). This function does not copy the list; the GConfValue will take ownership of the list and its contents, and they will be destroyed when the GConfValue is destroyed. Alternatively, use gconf_value_set_list() to make a copy.

value : a GConfValue with type GCONF_VALUE_LIST.
list : the GSList of GConfValue to set as the list value.

gconf_value_set_list ()

void                gconf_value_set_list                (GConfValue *value,
                                                         GSList *list);

Sets the value of a GConfValue with type GCONF_VALUE_LIST. The list argument should be a GSList of GConfValue. Each GConfValue in the list must have the same type, and this type must be specified in advance with gconf_value_set_list_type(). This function copies the list; it will not modify the list argument.

value : a GConfValue with type GCONF_VALUE_LIST.
list : the GSList of GConfValue to set as the list value.

gconf_value_to_string ()

gchar*              gconf_value_to_string               (const GConfValue *value);

Creates a human-readable string representation of a GConfValue. This is intended for debugging and the like; the string representation is not suitable for reliable machine parsing (that is, you shouldn't use this function to save a value to a file or anything like that). The exact nature of the string representation may change in future versions. The returned string is newly-allocated and must be freed with g_free().

value : a GConfValue.
Returns : a newly-allocated string representing the GConfValue.

GConfMetaInfo

typedef struct {
  gchar* schema;
  gchar* mod_user; /* user owning the daemon that made the last modification */
  GTime  mod_time; /* time of the modification */
} GConfMetaInfo;


gconf_meta_info_new ()

GConfMetaInfo*      gconf_meta_info_new                 (void);

Creates a new GConfMetaInfo structure and returns the newly allocated GConfMetaInfo.

Returns : the newly allocated GConfMetainfo.

gconf_meta_info_free ()

void                gconf_meta_info_free                (GConfMetaInfo *gcmi);

Frees the GConfMetaInfo.

gcmi : the GConfMetaInfo to be freed.

gconf_meta_info_get_schema ()

const char*         gconf_meta_info_get_schema          (GConfMetaInfo *gcmi);

Returns the schema field of the GConfMetaInfo.

gcmi : a GConfMetaInfo.
Returns : the schema field, a char* value.

gconf_meta_info_get_mod_user ()

const char*         gconf_meta_info_get_mod_user        (GConfMetaInfo *gcmi);

Returns the user owning the daemon that made the last modification of the key.

gcmi : a GConfMetaInfo.
Returns : mod_user, a char* value.

gconf_meta_info_mod_time ()

GTime               gconf_meta_info_mod_time            (GConfMetaInfo *gcmi);

Returns the last modification time of the key.

gcmi : a GConfMetaInfo.
Returns : the mod_time, a GTime value.

gconf_meta_info_set_schema ()

void                gconf_meta_info_set_schema          (GConfMetaInfo *gcmi,
                                                         const gchar *schema_name);

Sets the schema_name field of the GConfMetaInfo to the name passed.

gcmi : a GConfMetaInfo.
schema_name : the name to be set for the schema, a gchar* value.

gconf_meta_info_set_mod_user ()

void                gconf_meta_info_set_mod_user        (GConfMetaInfo *gcmi,
                                                         const gchar *mod_user);

Sets the mod_user field of the GConfMetaInfo to the user name passed.

gcmi : a GConfMetaInfo.
mod_user : the value to be set, a char*.

gconf_meta_info_set_mod_time ()

void                gconf_meta_info_set_mod_time        (GConfMetaInfo *gcmi,
                                                         GTime mod_time);

Sets the mod_last field of the GConfMetaInfo to the mod_time passed.

gcmi : a GConfMetaInfo.
mod_time : a GTime.

GConfEntry

typedef struct {
  char *key;
  GConfValue *value;
} GConfEntry;

Stores an entry from a GConf "directory," including a key-value pair, the name of the schema applicable to this entry, whether the value is a default value, and whether GConf can write a new value at this key. key should be an absolute key, not a relative key. (Note that internally GConf breaks this rule sometimes; but in the public interface, key is always an absolute key.) To access the key and value, use gconf_entry_get_key() and gconf_entry_get_value().

Warning

Value can be NULL, indicating that the value is not set.

char *key; an absolute key name.
GConfValue *value; the value.

gconf_entry_get_key ()

const char*         gconf_entry_get_key                 (const GConfEntry *entry);

Accesses the key field of a GConfEntry. The returned key is not a copy, and should not be freed or modified.

entry : a GConfEntry.
Returns : the key , a char*.

gconf_entry_get_value ()

GConfValue*         gconf_entry_get_value               (const GConfEntry *entry);

Accesses the value field of a GConfEntry. The returned value is not a copy, and should not be freed or modified. If you have called gconf_entry_steal_value(), the returned value will be NULL.

entry : a GConfEntry.
Returns : a GConfValue.

gconf_entry_get_schema_name ()

const char*         gconf_entry_get_schema_name         (const GConfEntry *entry);

Returns the schema_name field of the GConfEntry.

entry : a GConfEntry.
Returns : the schema_name , a char* value.

gconf_entry_get_is_default ()

gboolean            gconf_entry_get_is_default          (const GConfEntry *entry);

Returns the is_default field of the GConfEntry , a gboolean value.

entry : a GConfEntry.
Returns : a gboolean value.

gconf_entry_get_is_writable ()

gboolean            gconf_entry_get_is_writable         (const GConfEntry *entry);

Returns the is_writable field of the GConfEntry, a gboolean value.

entry : a GConfEntry.
Returns : a gboolean value.

gconf_entry_new ()

GConfEntry*         gconf_entry_new                     (const gchar *key,
                                                         const GConfValue *val);

Creates a new GConfEntry with key key and value val calling gconf_entry_new_nocopy().

key : the key name.
val : the value.
Returns : a new GConfEntry.

gconf_entry_new_nocopy ()

GConfEntry*         gconf_entry_new_nocopy              (gchar *key,
                                                         GConfValue *val);

Creates a new GConfEntry with key key and value val. key should be a full path to the key, starting with '/'. Neither the key nor the value is copied; both are freed when the GConfEntry is freed. The string will be freed with g_free() so should be allocated with a GLib function, not malloc().

key : the key name.
val : the value.
Returns : a new GConfEntry.

gconf_entry_copy ()

GConfEntry*         gconf_entry_copy                    (const GConfEntry *src);

Copies the fields of an existing GConfEntry and returns the new GConfEntry.

src : the GConfEntry to be copied.
Returns : the new GConfEntry.

gconf_entry_free ()

void                gconf_entry_free                    (GConfEntry *entry);

Warning

gconf_entry_free is deprecated and should not be used in newly-written code.

Destroys a GConfEntry, freeing the key, the value, and the entry itself.

entry : a GConfEntry to free.

gconf_entry_ref ()

void                gconf_entry_ref                     (GConfEntry *entry);

Increases the refcount of a GConfEntry by one.

entry : a GConfEntry.

gconf_entry_unref ()

void                gconf_entry_unref                   (GConfEntry *entry);

Decreases the refcount of a GConfEntry by one and frees the GConfEntry when the refcount becomes zero.

entry : a GConfEntry.

gconf_entry_steal_value ()

GConfValue*         gconf_entry_steal_value             (GConfEntry *entry);

Extracts the value from a GConfEntry, leaving the value field in GConfEntry set to NULL. Destroying the GConfEntry will not destroy the value; the caller of gconf_entry_steal_value() assumes ownership of it.

entry : a GConfEntry.
Returns : a GConfValue that the caller must free.

gconf_entry_set_value ()

void                gconf_entry_set_value               (GConfEntry *entry,
                                                         const GConfValue *val);

Sets the value field of the GConfEntry to the GConfValue passed.

entry : a GConfEntry.
val : a GConfValue.

gconf_entry_set_value_nocopy ()

void                gconf_entry_set_value_nocopy        (GConfEntry *entry,
                                                         GConfValue *val);

Sets the value field to val after freeing the already existing value.

entry : a GConfEntry.
val : the GConfValue to be set.

gconf_entry_set_schema_name ()

void                gconf_entry_set_schema_name         (GConfEntry *entry,
                                                         const gchar *name);

Sets the schema_name field of the GConfEntry to the name passed after freeing the already existing name.

entry : a GConfEntry.
name : the name to be set for the schema, a gchar* value.

gconf_entry_set_is_default ()

void                gconf_entry_set_is_default          (GConfEntry *entry,
                                                         gboolean is_default);

Sets the is_default field of the GConfEntry to the boolean value passed.

entry : a GConfEntry.
is_default : the boolean value to be set.

gconf_entry_set_is_writable ()

void                gconf_entry_set_is_writable         (GConfEntry *entry,
                                                         gboolean is_writable);

Sets the is_writable field of the GConfEntry to the boolean value passed.

entry : a GConfEntry.
is_writable : a boolean value.