11.4 Exception Handling
When an exception occurrence is raised, normal program
execution is abandoned and control is transferred to an applicable
exception_handler,
if any.
To
handle an exception occurrence
is to respond to the exceptional event.
To
propagate
an exception occurrence is to raise it again in another context; that
is, to fail to respond to the exceptional event in the present context.
Dynamic Semantics
Within a
given task, if the execution of construct
a is defined by this
International Standard to consist (in part) of the execution of construct
b, then while
b is executing, the execution of
a
is said to
dynamically enclose the execution of
b.
The
innermost dynamically enclosing execution of a given execution
is the dynamically enclosing execution that started most recently.
When
an exception occurrence is raised by the execution of a given construct,
the rest of the execution of that construct is
abandoned; that
is, any portions of the execution that have not yet taken place are not
performed. The construct is first completed, and then left, as explained
in
7.6.1. Then:
If the construct is a
task_body,
the exception does not propagate further;
Otherwise, the occurrence is
propagated to the innermost dynamically enclosing execution, which
means that the occurrence is raised again in that context.
Ada 2005 and 2012 Editions sponsored in part by Ada-Europe