7.3.3 Default Initial Conditions
For a private type
or private extension (including a generic formal type), the following
language-defined aspect may be specified with an
aspect_specification
(see
13.1.1):
Default_Initial_Condition
This aspect shall be specified by an
expression,
called a
default initial condition expression. Default_Initial_Condition
may be specified on a
private_type_declaration,
a
private_extension_declaration,
a
formal_private_type_definition,
or a
formal_derived_type_definition.
Name Resolution Rules
The expected type for a default initial condition
expression is any boolean type.
Legality Rules
The Default_Initial_Condition aspect shall not be
specified for a type whose partial view has unknown discriminants, whether
explicitly declared or inherited.
Static Semantics
If the Default_Initial_Condition aspect is specified
for a type T, then the default initial condition expression applies to
T and to all descendants of T.
Dynamic Semantics
If one or more default initial condition expressions
apply to a type T, then a default initial condition check is performed
after successful initialization of an object of type T by default (see
3.3.1). In the case of a controlled type,
the check is performed after the call to the type's Initialize procedure
(see
7.6).
If performing checks is required by the Default_Initial_Condition
assertion policy (see
11.4.2) in effect
at the point of the corresponding
aspect_specification
applicable to a given type, then the respective default initial condition
expression is considered enabled.
The default initial condition check consists of the
evaluation of each enabled default initial condition expression that
applies to T. These evaluations, if there are more than one, are performed
in an arbitrary order. If any of these evaluate to False, Assertions.Assertion_Error
is raised at the point of the object initialization.
For a generic formal type T, default initial condition
checks performed are as determined by the actual type, along with any
default initial condition of the formal type itself.
Implementation Permissions
Implementations may extend the syntax or semantics
of the Default_Initial_Condition aspect in an implementation-defined
manner.
14 For an example of the use of this aspect,
see the Vector container definition in
A.18.2.
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