8.2 Scope of Declarations
For each declaration, the language rules define a
certain portion of the program text called the scope of the declaration.
The scope of a declaration is also called the scope of any view or entity
declared by the declaration. Within the scope of an entity, and only
there, there are places where it is legal to refer to the declared entity.
These places are defined by the rules of visibility and overloading.
Static Semantics
The
immediate scope of a declaration is a portion of the declarative
region immediately enclosing the declaration. The immediate scope starts
at the beginning of the declaration, except in the case of an overloadable
declaration, in which case the immediate scope starts just after the
place where the profile of the callable entity is determined (which is
at the end of the
_specification for the callable
entity, or at the end of the
generic_instantiation
if an instance). The immediate scope extends to the end of the declarative
region, with the following exceptions:
The immediate scope of a
library_item
includes only its semantic dependents.
The immediate scope of a declaration in the private
part of a library unit does not include the visible part of any public
descendant of that library unit.
The
visible part of (a
view of) an entity is a portion of the text of its declaration containing
declarations that are visible from outside.
The
private
part of (a view of) an entity that has a visible part contains all
declarations within the declaration of (the view of) the entity, except
those in the visible part; these are not visible from outside. Visible
and private parts are defined only for these kinds of entities: callable
entities, other program units, and composite types.
The visible part of a view
of a callable entity is its profile.
The visible part of a composite
type other than a task or protected type consists of the declarations
of all components declared (explicitly or implicitly) within the
type_declaration.
The visible part of a package, task unit, or protected
unit consists of declarations in the program unit's declaration other
than those following the reserved word
private, if any; see
7.1
and
12.7 for packages,
9.1
for task units, and
9.4 for protected units.
The scope of a declaration always
contains the immediate scope of the declaration. In addition, for a given
declaration that occurs immediately within the visible part of an outer
declaration, or is a public child of an outer declaration, the scope
of the given declaration extends to the end of the scope of the outer
declaration, except that the scope of a
library_item
includes only its semantic dependents.
The immediate scope of a declaration
is also the immediate scope of the entity or view declared by the declaration.
Similarly, the scope of a declaration is also the
scope of the entity or view declared by the declaration.
4 There are notations for denoting visible
declarations that are not directly visible. For example,
parameter_specifications
are in the visible part of a
subprogram_declaration
so that they can be used in named-notation calls appearing outside the
called subprogram. For another example, declarations of the visible part
of a package can be denoted by expanded names appearing outside the package,
and can be made directly visible by a
use_clause.
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