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6 GError

error reporting.

6.1 Overview

The <g-error> 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 <g-error>**, a pointer to a location where a <g-error>* can be placed.

This last argument may be , in which case no error will be returned.

If non-, the argument should be the address of a <g-error>* variable, which should be initialized to .

If an error occurs, a <g-error> will be allocated and placed in the return location; the caller must free the <g-error> 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, is returned on success. In some cases, a return value indicates failure. Either way, if the return value indicates failure and you passed a non- value for the last argument to the function, a <g-error> will be returned. If the return value indicates success, then a <g-error> will never be returned. These relationships are guaranteed; that is, you can reliably use the return value to decide whether a <g-error> was placed in the return location. If a function does not indicate success/failure by return value, you must check whether the <g-error> is 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);
           err = NULL;

6.2 Usage