1.3.1 Types, Objects, and their Properties
tagged type intended for use as an ancestor of
other types, but which is not allowed to have objects of its own
type that has values that designate aliased objects
Note: Access types correspond
to “pointer types” or “reference types” in some
other languages.
representation of the lifetime of an entity in
terms of the level of dynamic nesting within which the entity is known
to exist
view of an object that can be designated by an
access value
Note: Objects allocated
by allocators are aliased. Objects can also be explicitly declared as
aliased with the reserved word aliased. The Access attribute can be used
to create an access value designating an aliased object.
type itself or, in the case of a type derived from
other types, its parent type or one of its progenitor types or one of
their ancestors
Note: Ancestor and descendant
are inverse relationships.
composite type whose components are all of the
same type
specifiable property of an entity
Note: An aspect can be
specified by an aspect_specification
on the declaration of the entity. Some aspects can be queried via attributes.
characteristic or property of an entity that can
be queried, and in some cases specified
set of types with one or more common properties,
such as primitive operations
Note: A category of types
that is closed under derivation is also known as a class.
enumeration type whose values include characters
set of types that is closed
under derivation, which means that if a given type is in the class, then
all types derived from that type are also in the class
Note: The set of types
of a class share common properties, such as their primitive operations.
type with components, such as an array or record
type that supports user-defined assignment and
finalization
Note: Objects are always
finalized before being destroyed.
default
initial condition
property that holds for every default-initialized
object of a given type
type defined in terms of a parent type and zero
or more progenitor types given in a derived type definition
Note 1: A derived type
inherits properties such as components and primitive operations from
its parent and progenitors.
Note 2: A type together
with the types derived from it (directly or indirectly) form a derivation
class.
type itself or a type derived (directly or indirectly)
from it
Note: Descendant and ancestor
are inverse relationships.
type that is either an integer type or an enumeration
type
parameter for a composite type, which can control,
for example, the bounds of a component that is an array
Note: A discriminant for
a task type can be used to pass data to a task of the type upon its creation.
type that does not have components
type defined by an enumeration of its values, which
can be denoted by identifiers or character literals
type that defines a full view
view of a type that reveals all of its properties
Note: There can be other
views of the type that reveal fewer properties.
type that defines an incomplete view
Note: Incomplete types
can be used for defining recursive data structures.
view of a type that reveals minimal properties
Note: The remaining properties
are defined by the full view given elsewhere.
type that has user-defined behavior for indexing,
via the Constant_Indexing or Variable_Indexing aspects
type that represents signed or modular integers
Note: A signed integer
type has a base range that includes both positive and negative numbers,
and has operations that can raise an exception when the result is outside
the base range. A modular type has a base range whose lower bound is
zero, and has operations with “wraparound” semantics. Modular
types subsume what are called “unsigned types” in some other
languages.
abstract tagged type that has no components or
concrete operations except possibly null procedures
Note: Interface types
are used for composing other interfaces and tagged types and thereby
provide multiple inheritance. Only an interface type can be used as a
progenitor of another type.
assertion that is expected to be True for all objects
of a given private type when viewed from outside the defining package
type that has user-defined behavior for iteration,
via the Default_Iterator and Iterator_Element aspects
type for which copying (such as in an assignment_statement)
is not allowed
Note: All types are either
limited types or nonlimited types.
component of a record type or record extension
that is required to have its value specified within a given aggregate
subtype specified when a view of an object is defined
type for which copying is allowed
entity that contains a value, and is either a constant
or a variable
Note: An object is created
by an object_declaration
or by an allocator.
A formal parameter is (a view of) an object. A subcomponent of an object
is an object.
aspect that indicates a logical property of an
entity, such as the precondition of a subprogram, or the procedure used
to write a given type of object to a stream
first ancestor type given in the definition of
the derived type
Note: The parent can be
almost any kind of type, including an interface type.
view of a type that reveals only some of its properties
Note: The remaining properties
are defined by the full view given elsewhere.
primitive
operations of a type
operations (such as subprograms) declared together
with the type declarations
Note: Primitive operations
are inherited by other types in the same derivation class of types.
type that extends another type, with the additional
properties hidden from its clients
type that defines a partial view
Note: Private types can
be used for defining abstractions that hide unnecessary details from
their clients.
type given in the interface list, if any, of an
interface, task, protected, or derived type definition
Note: A progenitor is
always an interface type.
composite type whose components are accessible
only through one of its protected operations, which synchronize concurrent
access by multiple tasks
type that has values that are approximations of
the real numbers
Note: Floating point and
fixed point types are real types.
type that extends another type optionally with
additional components
composite type consisting of zero or more named
components, possibly of different types
type that has user-defined behavior for “.all”,
defined by the Implicit_Dereference aspect
aspect that indicates how an entity is mapped onto
the underlying hardware, for example the size or alignment of an object
either a discrete type or a real type
characteristic associated with objects of a given
type that is preserved by many of the primitive operations of the type
object associated with one or more access types
from which the storage for objects created by allocators of the access
type(s) is obtained
Note: Some storage pools
can be partitioned into subpools in order to support finer-grained storage
management.
sequence of elements that can be used, along with
the stream-oriented attributes, to support marshalling and unmarshalling
of values of most types
type together with optional constraints, null exclusions,
and predicates, which constrain the values of the type to the subset
that satisfies the implied conditions
can be safely operated on by multiple tasks concurrently
Note: Synchronized is
used to qualify entities, as in a synchronized interface.
type whose objects each have a run-time type tag,
which indicates the specific type for which the object was originally
created
Note: Tagged types can
be extended with additional components.
composite type used to represent active entities
which execute concurrently and that can communicate via queued task entries
Note: The top-level task
of a partition is called the environment task.
defining characteristic of each object and expression
of the language, with an associated set of values, and a set of primitive
operations that implement the fundamental aspects of its semantics
Note: Types are grouped
into categories. Most language-defined categories of types are also classes
of types.
representation of an entity that reveals some or
all of the properties of the entity
Note: A single entity
can have multiple views.
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