Exceptions

Ada provides an exception mechanism. There are two types of exception: predefined exceptions and dedicated language exceptions. Predefined exceptions have clear execution-related semantics: Constraint_error (assignment of a type incompatible with the associated variable, overflow in array indices, etc.), Storage_Error which signals memory management problems (typically when memory runs out), Tasking_Error linked to task management problems, and finally Program_Error in other cases (for example, arriving at the end of a function without having encountered a return instruction).

Exceptions dedicated to a program are defined in a declarative part.

Predefined exceptions are generally raised "implicitly", i.e. by code automatically generated by the compiler. Exceptions defined by the programmer must be raised explicitly using the raise statement...