diff options
| -rw-r--r-- | include/qapi/error.h | 51 |
1 files changed, 36 insertions, 15 deletions
diff --git a/include/qapi/error.h b/include/qapi/error.h index e8960eaad5..6d079c58b7 100644 --- a/include/qapi/error.h +++ b/include/qapi/error.h @@ -15,6 +15,8 @@ /* * Error reporting system loosely patterned after Glib's GError. * + * = Creating errors = + * * Create an error: * error_setg(&err, "situation normal, all fouled up"); * @@ -27,6 +29,8 @@ * error_setg(&err, "invalid quark\n" // WRONG! * "Valid quarks are up, down, strange, charm, top, bottom."); * + * = Reporting and destroying errors = + * * Report an error to the current monitor if we have one, else stderr: * error_report_err(err); * This frees the error object. @@ -40,6 +44,30 @@ * error_free(err); * Note that this loses hints added with error_append_hint(). * + * Call a function ignoring errors: + * foo(arg, NULL); + * This is more concise than + * Error *err = NULL; + * foo(arg, &err); + * error_free(err); // don't do this + * + * Call a function aborting on errors: + * foo(arg, &error_abort); + * This is more concise and fails more nicely than + * Error *err = NULL; + * foo(arg, &err); + * assert(!err); // don't do this + * + * Call a function treating errors as fatal: + * foo(arg, &error_fatal); + * This is more concise than + * Error *err = NULL; + * foo(arg, &err); + * if (err) { // don't do this + * error_report_err(err); + * exit(1); + * } + * * Handle an error without reporting it (just for completeness): * error_free(err); * @@ -47,6 +75,11 @@ * reporting it (primarily useful in testsuites): * error_free_or_abort(&err); * + * = Passing errors around = + * + * Errors get passed to the caller through the conventional @errp + * parameter. + * * Pass an existing error to the caller: * error_propagate(errp, err); * where Error **errp is a parameter, by convention the last one. @@ -54,11 +87,10 @@ * Pass an existing error to the caller with the message modified: * error_propagate_prepend(errp, err, * "Could not frobnicate '%s': ", name); - * - * Avoid - * error_propagate(errp, err); + * This is more concise than + * error_propagate(errp, err); // don't do this * error_prepend(errp, "Could not frobnicate '%s': ", name); - * because this fails to prepend when @errp is &error_fatal. + * and works even when @errp is &error_fatal. * * Create a new error and pass it to the caller: * error_setg(errp, "situation normal, all fouled up"); @@ -70,15 +102,6 @@ * handle the error... * } * - * Call a function ignoring errors: - * foo(arg, NULL); - * - * Call a function aborting on errors: - * foo(arg, &error_abort); - * - * Call a function treating errors as fatal: - * foo(arg, &error_fatal); - * * Receive an error and pass it on to the caller: * Error *err = NULL; * foo(arg, &err); @@ -86,8 +109,6 @@ * handle the error... * error_propagate(errp, err); * } - * where Error **errp is a parameter, by convention the last one. - * * Do *not* "optimize" this to * foo(arg, errp); * if (*errp) { // WRONG! |