1.3 Terms and Definitions

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Terms are defined throughout this document, indicated by italic type. Terms explicitly defined in this document are not to be presumed to refer implicitly to similar terms defined elsewhere. Mathematical terms not defined in this document are to be interpreted according to the CRC Concise Encyclopedia of Mathematics, Second Edition. Other terms not defined in this document are to be interpreted according to the Webster's Third New International Dictionary of the English Language. Informal descriptions of some terms are also given below .

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discussion

The index contains an entry for every defined term.

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The contents of the CRC Concise Encyclopedia of Mathematics, Second Edition can be accessed on http://www.mathworld.com. The ISBN number of the book is ISBN 1584883472.

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The definitions found in this subclause are short, descriptive definitions. These are most useful for comprehension when an exact meaning is not needed. More formal, detailed definitions are found in the body of the Reference Manual; these are needed to determine the exact application of rules to constructs and entities.

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To see the difference, consider “aliased view”. The descriptive definition is “a view of an object that can be designated by an access value”. The formal definition is a lengthy paragraph in 3.10 that defines 10 separate constructs as aliased views. In order to reason about a language rule that requires an aliased view in a particular context, one needs to look at the list of constructs in order to determine if the object in hand is actually an aliased view. The descriptive definition is no help in this case.

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Term entry: Each term defined in this subclause is marked like this in the body of the AARM near its detailed formal definition.

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discussion

Here are some AARM-only definitions: The Ada Rapporteur Group (ARG) interprets the Ada Reference Manual. An Ada Issue (AI) is a numbered ruling from the ARG. Ada Issues created for Ada 83 are denoted as "AI83", while Ada Issues created for Ada 95 are denoted as "AI95" in this document. Similarly, Ada Issues created for Ada 2005 are denoted as "AI05", Ada Issues created for Ada 2012 are denoted as "AI12", and Ada Issues created for Ada 2022 are denoted as "AI22". The Ada Commentary Integration Document (ACID) is an edition of the Ada 83 RM in which clearly marked insertions and deletions indicate the effect of integrating the approved AIs. The Uniformity Rapporteur Group (URG) issued recommendations intended to increase uniformity across Ada implementations. The functions of the URG have been assumed by the ARG. A Uniformity Issue (UI) was a numbered recommendation from the URG. A Defect Report and Response is an official query to WG9 about an error in the standard. Defect Reports are processed by the ARG, and are referenced here by their ISO numbers: 8652/nnnn. Most changes to the Ada 95 standard include reference(s) to the Defect Report(s) that prompted the change. The Ada Conformity Assessment Test Suite (ACATS) is a set of tests intended to check the conformity of Ada implementations to this standard. This set of tests was previously known as the Ada Compiler Validation Capability (ACVC).

1.3.1 Types, Objects, and their Properties

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abstract type

tagged type intended for use as an ancestor of other types, but which is not allowed to have objects of its own
access type: type that has values that designate aliased objects

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accessibility level

representation of the lifetime of an entity in terms of the level of dynamic nesting within which the entity is known to exist
aliased view: view of an object that can be designated by an access value

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ancestor of a type

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

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array type

composite type whose components are all of the same type
aspect: specifiable property of an entity

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aspect_specification on the declaration of the entity. Some aspects can be queried via attributes.

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attribute

characteristic or property of an entity that can be queried, and in some cases specified
category of types: set of types with one or more common properties, such as primitive operations

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character type

enumeration type whose values include characters
class of types: 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

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composite type

type with components, such as an array or record
controlled type: type that supports user-defined assignment and finalization

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default initial condition

property that holds for every default-initialized object of a given type
derived type: type defined in terms of a parent type and zero or more progenitor types given in a derived type definition

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Note 1: A derived type inherits properties such as components and primitive operations from its parent and progenitors.

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Note 2: A type together with the types derived from it (directly or indirectly) form a derivation class.

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descendant of a type

type itself or a type derived (directly or indirectly) from it

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discrete type

type that is either an integer type or an enumeration type
discriminant: parameter for a composite type, which can control, for example, the bounds of a component that is an array

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elementary type

type that does not have components
enumeration type: type defined by an enumeration of its values, which can be denoted by identifiers or character literals
full type: type that defines a full view
full view: view of a type that reveals all of its properties

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incomplete type

type that defines an incomplete view

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incomplete view

view of a type that reveals minimal properties

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indexable container type

type that has user-defined behavior for indexing, via the Constant_Indexing or Variable_Indexing aspects
integer type: type that represents signed or modular integers

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interface type

abstract tagged type that has no components or concrete operations except possibly null procedures

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invariant

assertion that is expected to be True for all objects of a given private type when viewed from outside the defining package
iterable container type: type that has user-defined behavior for iteration, via the Default_Iterator and Iterator_Element aspects
limited type: type for which copying (such as in an assignment_statement) is not allowed

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needed component

component of a record type or record extension that is required to have its value specified within a given aggregate
nominal subtype: subtype specified when a view of an object is defined
nonlimited type: type for which copying is allowed
object: entity that contains a value, and is either a constant or a variable

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object_declaration or by an allocator. A formal parameter is (a view of) an object. A subcomponent of an object is an object.

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operational aspect

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
parent of a derived type: first ancestor type given in the definition of the derived type

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partial view

view of a type that reveals only some of its properties

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primitive operations of a type

operations (such as subprograms) declared together with the type declarations

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private extension

type that extends another type, with the additional properties hidden from its clients
private type: type that defines a partial view

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progenitor

type given in the interface list, if any, of an interface, task, protected, or derived type definition

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protected type

composite type whose components are accessible only through one of its protected operations, which synchronize concurrent access by multiple tasks
real type: type that has values that are approximations of the real numbers

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record extension

type that extends another type optionally with additional components
record type: composite type consisting of zero or more named components, possibly of different types
reference type: type that has user-defined behavior for “.all”, defined by the Implicit_Dereference aspect
representation aspect: aspect that indicates how an entity is mapped onto the underlying hardware, for example the size or alignment of an object
scalar type: either a discrete type or a real type
stable property: characteristic associated with objects of a given type that is preserved by many of the primitive operations of the type
storage pool object: object associated with one or more access types from which the storage for objects created by allocators of the access type(s) is obtained

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stream

sequence of elements that can be used, along with the stream-oriented attributes, to support marshalling and unmarshalling of values of most types
subtype: type together with optional constraints, null exclusions, and predicates, which constrain the values of the type to the subset that satisfies the implied conditions
synchronized: can be safely operated on by multiple tasks concurrently

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tagged type

type whose objects each have a run-time type tag, which indicates the specific type for which the object was originally created

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task type

composite type used to represent active entities which execute concurrently and that can communicate via queued task entries

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type

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

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view of an entity

representation of an entity that reveals some or all of the properties of the entity

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1.3.2 Subprograms and their Properties

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function

form of subprogram that returns a result and can be called as part of an expression
overriding operation: operation that replaces an inherited primitive operation

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postcondition

assertion that is expected to be True when a given subprogram returns normally
precondition: assertion that is expected to be True when a given subprogram is called
procedure: form of subprogram that does not return a result and can only be invoked by a statement
subprogram: unit of a program that can be brought into execution in various contexts, with the invocation being a subprogram call that can parameterize the effect of the subprogram through the passing of operands

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1.3.3 Other Syntactic Constructs

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aggregate

construct used to define a value of a composite type by specifying the values of the components of the type
compilation unit: program unit that is separately compiled

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compilation_unit contains either the declaration, the body, or a renaming of a program unit.

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construct

piece of text (explicit or implicit) that is an instance of a syntactic category defined under Syntax
container: structured object that represents a collection of elements all of the same (potentially class-wide) type, such as a vector or a tree

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container aggregate

construct used to define a value of a type that represents a collection of elements, by explicitly specifying the elements in the collection
core language: clause or annex in which are defined language constructs or capabilities that are provided by all conforming implementations

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declaration

language construct that associates a name with (a view of) an entity

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generic instance

nongeneric unit created by the instantiation of a generic unit
generic unit: template for a (nongeneric) program unit

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Note 1: The template can be parameterized by objects, types, subprograms, and packages.

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Note 2: Generic units can be used to perform the role that macros sometimes play in other languages.

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iterator

construct that is used to loop over the elements of an array or container

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iterator filter

construct that is used to restrict the elements produced by an iteration to those for which a boolean condition evaluates to True
library unit: separately compiled program unit, which is a package, a subprogram, or a generic unit

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master construct

one of certain executable constructs for which there can be objects or tasks whose lifetime ends when the construct completes

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needed compilation unit

compilation unit that is necessary to produce an executable partition, because some entity declared or defined within the unit is used elsewhere in the partition
package: program unit that defines the interface to a group of logically related entities, along with their implementation

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parallel construct

executable construct that defines multiple activities of a single task that can proceed in parallel, via the execution of multiple logical threads of control
partition: part of a program, which consists of a set of interdependent library units

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pragma

compiler directive to provide control over and above that provided by the other syntactic constructs of the language

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program

set of partitions, each of which can execute in a separate address space, possibly on a separate computer
program unit: language construct that is a package, a task unit, a protected unit, a protected entry, a generic unit, or an explicitly declared subprogram other than an enumeration literal

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reduction expression

expression that defines how to map or transform a collection of values into a new set of values, and then summarize the values by applying an operation to reduce the set to a single value
renaming: declaration that does not define a new entity, but instead defines a new view of an existing entity
specialized needs annex: annex in which are defined language constructs or capabilities that are not necessarily provided by all conforming implementations
subunit: body of a program unit that can be compiled separately from its enclosing program unit

1.3.4 Runtime Actions

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assertion

boolean expression that is expected to be True at run time at certain specified places

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elaboration

process by which a declaration achieves its run-time effect

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evaluation

process by which an expression achieves its run-time effect

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execution

process by which a construct achieves its run-time effect

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logical thread of control

activity within the execution of a program that can proceed in parallel with other activities of the same task, or of separate tasks
master: execution of a master construct

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1.3.5 Exceptional Situations

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check

test made during execution to determine whether a language rule has been violated
exception: kind of exceptional situation
exception occurrence: run-time occurrence of an exceptional situation
handle an exception: perform some actions in response to the arising of an exception
raise an exception: abandon normal program execution so as to draw attention to the fact that the corresponding situation has arisen
suppress a check: assert that the check cannot fail, and request that the compiler optimize by disabling the check

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1.3 Terms and Definitions

1.3.1 Types, Objects, and their Properties​

1.3.2 Subprograms and their Properties​

1.3.3 Other Syntactic Constructs​

1.3.4 Runtime Actions​

1.3.5 Exceptional Situations​

1.3.1 Types, Objects, and their Properties

1.3.2 Subprograms and their Properties

1.3.3 Other Syntactic Constructs

1.3.4 Runtime Actions

1.3.5 Exceptional Situations