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Volume 7A: XView Programming Manual
book

Volume 7A: XView Programming Manual

by Dan Heller
October 1994
Intermediate to advanced content levelIntermediate to advanced
770 pages
22h 58m
English
O'Reilly Media, Inc.
Content preview from Volume 7A: XView Programming Manual
NULL);
break;
/* ... */
}
As you can see, unless you are implementing the internals of an XView package,
xv_error() may be of limited use. However, this example demonstrates how
xv_error() can be called internally by XView.
24.4.1.1 Error severity
In the above example, the reason to call xv_error() is not a serious one, at least not one
that should terminate the program. By default, calling xv_error() is a recoverable error,
so in order to specify a non-recoverable error, the call to xv_error() should pass the attri-
bute, ERROR_SEVERITY, and the value ERROR_NON_RECOVERABLE. Unrecoverable errors
generally terminate using exit() with a non-zero exit status. However, abort() may be
used instead to generate a core image used for debugging.
In any event, if the error handler is called, it should print a warning message and either con-
tinue or exit accordingly. If you install your own error routine, the choice is yours. Example
24-1 in the next section, shows how the error severity can be evaluated and acted upon
accordingly.
24.4.2 Revisiting the Error Handler
Advanced usage of the ERROR package provides us with the ability to scan the attribute list in
search of the causes of the error. With this information, you can print out more useful error
messages or display them in a manner other than printing to stderr.
Recall that there are two parameters passed to the function:
error_proc(object, avlist)
Xv_object object;
Attr_avlist avlist;
object is the object in which the xv_* call failed to operate. You
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Publisher Resources

ISBN: 9780937175873