Ada Reference Manual (Ada 2022)

11.1 Exception Declarations

An exception_declaration declares a name for an exception.

Syntax

exception_declaration ::= defining_identifier_list : exception
[aspect_specification];

Static Semantics

Each single exception_declaration declares a name for a different exception. If a generic unit includes an exception_declaration, the exception_declarations implicitly generated by different instantiations of the generic unit refer to distinct exceptions (but all have the same defining_identifier). The particular exception denoted by an exception name is determined at compilation time and is the same regardless of how many times the exception_declaration is elaborated.

The predefined exceptions are the ones declared in the declaration of package Standard: Constraint_Error, Program_Error, Storage_Error, and Tasking_Error; one of them is raised when a language-defined check fails.

Dynamic Semantics

The elaboration of an exception_declaration has no effect.

The execution of any construct raises Storage_Error if there is insufficient storage for that execution. The amount of storage necessary for the execution of constructs is unspecified.

Examples

Examples of user-defined exception declarations:

Singular : exception;
Error : exception;
Overflow, Underflow : exception;