|  |  |  | GConf Reference Manual |  | 
|---|---|---|---|---|
enum GConfError; GError* gconf_error_new (GConfError en, const gchar *format, ...); GQuark gconf_error_quark (void); void gconf_set_error (GError **err, GConfError en, const gchar *format, ...); GError* gconf_compose_errors (GError *err1, GError *err2);
The GError object is used to report errors that occur in GConf library routines. All functions that report errors work the same way:
The last argument to the function is a GError**, a pointer to a location where a GError* can be placed.
This last argument may be NULL, in which case no error will be returned.
If non-NULL, the argument should be the address of a GError* variable, which should be initialized to NULL.
If an error occurs, a GError will be allocated and placed in the
return location; the caller must free the GError with
g_error_free(). If no error occurs, the return location will be
left untouched. That is, the test error != NULL 
should always be a reliable indicator of whether the operation failed.
It's also common that the return value of a function indicates whether or not an error occurred. Typically, TRUE is returned on success. In some cases, a NULL return value indicates failure. Either way, if the return value indicates failure and you passed a non-NULL value for the last argument to the function, a GError will be returned. If the return value indicates success, then a GError will never be returned. These relationships are guaranteed; that is, you can reliably use the return value to decide whether a GError was placed in the return location. If a function does not indicate success/failure by return value, you must check whether the GError is NULL to detect errors.
Here's a short error handling example:
  GError* err = NULL;
  if (!gconf_init(&err))
    {
      fprintf(stderr, _("Failed to init GConf: s\n"), err->message);
      g_error_free(err); 
      err = NULL;
    }
typedef enum {
  GCONF_ERROR_SUCCESS = 0,
  GCONF_ERROR_FAILED = 1,        /* Something didn't work, don't know why, probably unrecoverable
                                    so there's no point having a more specific errno */
  GCONF_ERROR_NO_SERVER = 2,     /* Server can't be launched/contacted */
  GCONF_ERROR_NO_PERMISSION = 3, /* don't have permission for that */
  GCONF_ERROR_BAD_ADDRESS = 4,   /* Address couldn't be resolved */
  GCONF_ERROR_BAD_KEY = 5,       /* directory or key isn't valid (contains bad
                                    characters, or malformed slash arrangement) */
  GCONF_ERROR_PARSE_ERROR = 6,   /* Syntax error when parsing */
  GCONF_ERROR_CORRUPT = 7,       /* Fatal error parsing/loading information inside the backend */
  GCONF_ERROR_TYPE_MISMATCH = 8, /* Type requested doesn't match type found */
  GCONF_ERROR_IS_DIR = 9,        /* Requested key operation on a dir */
  GCONF_ERROR_IS_KEY = 10,       /* Requested dir operation on a key */
  GCONF_ERROR_OVERRIDDEN = 11,   /* Read-only source at front of path has set the value */
  GCONF_ERROR_OAF_ERROR = 12,    /* liboaf error */
  GCONF_ERROR_LOCAL_ENGINE = 13, /* Tried to use remote operations on a local engine */
  GCONF_ERROR_LOCK_FAILED = 14,  /* Failed to get a lockfile */
  GCONF_ERROR_NO_WRITABLE_DATABASE = 15, /* nowhere to write a value */
  GCONF_ERROR_IN_SHUTDOWN = 16   /* server is shutting down */
} GConfError;
The GConfError enumeration allows client applications to differentiate between different kinds of error. You may wish to take specific actions depending on the error type.
| GCONF_ERROR_SUCCESS | indicates that no error occurred, won't be returned in a GError. | 
| GCONF_ERROR_FAILED | indicates failure, but no more specific GConfError applied. | 
| GCONF_ERROR_NO_SERVER | indicates that the GConf server couldn't be contacted, probably a CORBA problem. | 
| GCONF_ERROR_NO_PERMISSION | indicates that permission to access some resource was denied. | 
| GCONF_ERROR_BAD_ADDRESS | indicates that a configuration source address was syntactically invalid or impossible to resolve. | 
| GCONF_ERROR_BAD_KEY | indicates that a key was malformed. | 
| GCONF_ERROR_PARSE_ERROR | indicates that some parsing was done (perhaps in a backend) and it failed. | 
| GCONF_ERROR_CORRUPT | indicates that some part of the database is corrupt. | 
| GCONF_ERROR_TYPE_MISMATCH | indicates that a specific type was required, and another type was found. | 
| GCONF_ERROR_IS_DIR | indicates that an operation only applicable to keys was performed on a directory. | 
| GCONF_ERROR_IS_KEY | indicates that an operation only applicable to directories was performed on a key. | 
| GCONF_ERROR_OVERRIDDEN | indicates that the administrator has imposed a mandatory value, and it could not be changed. | 
| GCONF_ERROR_OAF_ERROR | |
| GCONF_ERROR_LOCAL_ENGINE | |
| GCONF_ERROR_LOCK_FAILED | |
| GCONF_ERROR_NO_WRITABLE_DATABASE | |
| GCONF_ERROR_IN_SHUTDOWN | 
GError* gconf_error_new (GConfError en, const gchar *format, ...);
Creates a new error. Normally the GConf library does this, but you
might find a reason to do it as well. en is the error number, format
is a printf()-style format for the error message, and the variable
argument list is the same as in printf(). 
| en: | the error number. | 
| format: | printf()-style format for error description. | 
| ...: | arguments required by the format. | 
| Returns : | newly-allocated GError. | 
GQuark gconf_error_quark (void);
Converts the string 'gconf-error-quark' to a GQuark and returns the value.
| Returns : | the GQuark representing the string. | 
void gconf_set_error (GError **err, GConfError en, const gchar *format, ...);
Internal function.
| err: | |
| en: | |
| format: | |
| ...: |