Section 11: Exceptions
[This section defines the facilities for dealing
with errors or other exceptional situations that arise during program
represents a kind of exceptional situation; an occurrence
of such a situation (at run time) is called an exception occurrence
an exception is to abandon normal
program execution so as to draw attention to the fact that the corresponding
situation has arisen.
Performing some actions in
response to the arising of an exception is called handling
To be honest:
handling the exception occurrence.
Ramification: For example, an exception
End_Error might represent error situations in which an attempt is made
to read beyond end-of-file. During the execution of a partition, there
might be numerous occurrences of this exception.
To be honest:
the meaning is clear from the context, we sometimes use “occurrence
as a short-hand for “exception occurrence.”
Wording Changes from Ada 83
We are more explicit about the difference between
an exception and an occurrence of an exception. This is necessary because
we now have a type (Exception_Occurrence) that represents exception occurrences,
so the program can manipulate them. Furthermore, we say that when an
exception is propagated, it is the same occurrence that is being propagated
(as opposed to a new occurrence of the same exception). The same issue
applies to a re-raise statement. In order to understand these semantics,
we have to make this distinction.
Wording Changes from Ada 2005
Correction: Generalized the introductory
description of how an exception can be raised so that it does not appear
to cover all of the cases.
Ada 2005 and 2012 Editions sponsored in part by Ada-Europe