!standard 0.3   (3)                                 05-05-23  AI95-00387/04
!standard 0.3   (5)
!standard 0.3   (6)
!standard 0.3   (32)
!standard 0.3   (34)
!standard 0.3   (38)
!standard 0.3   (41)
!standard 0.3   (42)
!standard 0.3   (44)
!standard 0.3   (45)
!standard 0.3   (46)
!standard 0.3   (47)
!standard 0.3   (48)
!standard 0.3   (49)
!standard 0.3   (50)
!standard 0.3   (51)
!standard 0.3   (57)
!class amendment 04-10-30
!status Amendment 200Y 04-12-01
!status ARG Approved 10-0-0  04-11-20
!status work item 04-10-30
!status received 04-10-30
!priority High
!difficulty Easy
!subject Introduction to Amendment

!summary

This revises the introduction to the International Standard in order to
reflect the changes made by the Amendment.

!problem

We need a new Introduction.

!proposal

Old John was volunteered to write it.

!wording

Replace 0(3) by

   * Ada 95 Rationale. This gives an introduction to the new features of
     Ada incorporated in the 1995 edition of this Standard, and explains
     the rationale behind them. Programmers unfamiliar with Ada 95 should
     read this first.

   * Ada 2006 Rationale. This gives an introduction to the changes and new
     features in Ada 2006 (compared with the 1995 edition), and explains
     the rationale behind them. Programmers should read this rationale
     before reading this Standard in depth.

Curiously the old version refers to "Rationale for the Ada Programming
Language - 1995 edition". It was never called that to my mind. That was
sort of the title for the Ada 83 rationale.

Modify 0(5) thus

   ...all of the text in [the RM95]{this International Standard} ...


Modify 0(6) thus

   ...[This revision]{The 1995 revision} to the language was designed ...,
   and efficiency. {This amended version provides further flexibility and
   adds more standardized packages within the framework provided by the 1995
   revision.}

Modify 0(32) thus

   ...The enumeration types Boolean, Character,[and] Wide_Character{, and
   Wide_Wide_Character} are predefined.

Modify 0(34) thus

   ...The array types String,[and] Wide_String{, and Wide_Wide_String} are
   predefined.

Add after 0(38)

   Interface types provide abstract models from which other interfaces and
   types may be composed and derived. This provides a reliable form of multiple
   inheritance. Interface types may also be implemented by synchronized types
   (task types and protected types) thereby enabling concurrent programming and
   inheritance to be merged.

Modify 0(41)

   [Representation]{Aspect} clauses ...

Modify 0(42)

   ...and other capabilities[(such as string manipulation and random number
   generation)] by means ...[Other standard library packages are defined in
   annexes of the standard to support systems with specialized requirements.]

Add after 0(42)

   The predefined standard library packages provide facilities such as string
   manipulation, containers of various kinds (vectors, lists, maps etc.),
   mathematical functions, random number generation, and access to the
   execution environment.

   The specialized annexes define further predefined library packages and
   facilities with emphasis on areas such as real-time scheduling,
   interrupt handling, distributed systems, numerical computation, and
   high-integrity systems.

Replace 0(44-51)

   This amended International Standard updates the edition of 1995 which
   replaced the first edition of 1987. In the 1995 edition, the following
   major language changes were incorporated:

(The original list was a bit inconsistent. It started with noun clauses and
then switched to sentences. And it needed changing to the past tense.)

   * Support for standard 8-bit and 16-bit characters was added. See
     clauses 2.1, 3.5.2, 3.6.3, A.1, A.3, and A.4.

   * The type model was extended to include facilities for object-oriented
     programming with dynamic polymorphism. See the discussions of classes,
     derived types, tagged types, record extensions, and private extensions in
     clauses 3.4, 3.9, and 7.3. Additional forms of generic formal parameters
     were allowed as described in clauses 12.5.1 and 12.7.

   * Access types were extended to allow an access value to designate a
     subprogram or an object declared by an object declaration as opposed to
     just an object allocated on a heap. See clause 3.10.

   * Efficient data-oriented synchronization was provided by the introduction
     of protected types. See clause 9.4.

   * The library structure was extended to allow library units to be
     organized into a hierarchy of parent and child units. See clause 10.1.

   * Additional support was added for interfacing to other languages. See
     Annex B.

   * The Specialized Needs Annexes were added to provide specific support
     for certain application areas:

Replace 0(57)

     * Annex H, "High Integrity Systems" (originally "Safety and Security")

Add after 0(57)

   Amendment 1 modifies the 1995 International Standard by making changes and
   additions that improve the capability of the language and the reliability of
   programs written in the language. In particular the changes were designed to
   improve the portability of programs, interfacing to other languages, and
   both the object-oriented and real-time capabilities.

   The following significant changes with respect to the 1995 edition are
   incorporated:

   * Support for program text is extended to cover the entire ISO/IEC
     10646:2003 repertoire. Execution support now includes the 32-bit character
     set. See clauses 2.1, 3.5.2, 3.6.3, A.1, A.3, and A.4.

   * The object-oriented model has been improved by the addition of an
     interface facility which provides multiple inheritance and additional
     flexibility for type extensions. See clauses 3.4, 3.9, and 7.3. An
     alternative notation for calling operations more akin to that used in
     other languages has also been added. See clause 4.1.3.

   * Access types have been further extended to unify properties such as
     the ability to access constants and to exclude null values. See clause
     3.10. Anonymous access types are now permitted more freely and anonymous
     access-to-subprogram types are introduced. See clauses 3.3, 3.6, 3.10, and
     8.5.1.

   * The control of structure and visibility has been enhanced to
     permit mutually dependent references between units and finer control
     over access from the private part of a package. See clauses 3.10.1 and
     10.1.2. In addition, limited types have been made more useful by the
     provision of aggregates, constants, and constructor functions. See clauses
     4.3, 6.5, and 7.5.

   * The predefined environment has been extended to include additional time
     and calendar operations, improved string handling, a comprehensive
     container library, file and directory management, and access to
     environment variables. See clauses 9.6.1, A.4, A.16, A.17, and A.18.

   * Two of the Specialized Needs Annexes have been considerably enhanced:

     * The Real-Time Systems Annex now includes the Ravenscar profile for
       high-integrity systems, further dispatching policies such as Round Robin
       and Earliest Deadline First, support for timing events, and support for
       control of CPU time utilization. See clauses D.2, D.13, D.14,
       and D.15.

     * The Numerics Annex now includes support for real and complex vectors
       and matrices as previously defined in ISO/IEC 13813:1997 plus further
       basic operations for linear algebra. See clause G.3.

   * The overall reliability of the language has been enhanced by
     a number of improvements. These include new syntax which detects
     accidental overloading, as well as pragmas for making assertions and
     giving better control over the suppression of checks. See clauses 6.1,
     11.4.2, and 11.5.


!discussion

The overall description has not been changed very much (this reflects the
fact that this amendment is really a super polish to Ada 95 rather than a
rebuild). Apart from minor changes to the opening remarks, the changes are:

   The mention of wide-wide characters and strings. This is perhaps
unnecessary but the existing paragraphs lead one into doing that.

   A paragraph on interfaces was added. This is an important addition and
merits mention at this high level.

   The existing one paragraph on the predefined environment has been
extended to three paragraphs. Much of the additional capability is provided
through library packages and the existing description was probably too weak
anyway.

The list of changes from Ada 83/87 to Ada 95 has been retained but placed
in the past tense; a further list of major changes from Ada 95 to Ada 2006
has been added.

!example

Not applicable

!corrigendum 0.3(3)

@drepl
@xbullet<Rationale for the Ada Programming Language -- 1995 edition, which
gives an introduction to the new features of Ada, and explains the rationale
behind them. Programmers should read this first.>
@dby
@xbullet<Ada 95 Rationale. This gives an introduction to the new features of
Ada incorporated in the 1995 edition of this Standard, and explains
the rationale behind them. Programmers unfamiliar with Ada 95 should
read this first.>

@xbullet<Ada 2006 Rationale. This gives an introduction to the changes and new
features in Ada 2006 (compared with the 1995 edition), and explains
the rationale behind them. Programmers should read this rationale
before reading this Standard in depth.>

!corrigendum 0.3(5)

@drepl
@xbullet<The Annotated Ada Reference Manual (AARM). The AARM contains all of
the text in the RM95, plus various annotations. It is intended primarily for
compiler writers, validation test writers, and others who wish to study the
fine details. The annotations include detailed rationale for individual rules
and explanations of some of the more arcane interactions among the rules.>
@dby
@xbullet<The Annotated Ada Reference Manual (AARM). The AARM contains all of
the text in the consolidated Ada Reference Manual, plus various annotations. It
is intended primarily for compiler writers, validation test writers, and others
who wish to study the fine details. The annotations include detailed rationale
for individual rules and explanations of some of the more arcane interactions
among the rules.>

!corrigendum 0.3(6)

@drepl
Ada was originally designed with three overriding concerns: program reliability
and maintenance, programming as a human activity, and efficiency. This revision
to the language was designed to provide greater flexibility and extensibility,
additional control over storage management and synchronization, and
standardized packages oriented toward supporting important application areas,
while at the same time retaining the original emphasis on reliability,
maintainability, and efficiency.
@dby
Ada was originally designed with three overriding concerns: program reliability
and maintenance, programming as a human activity, and efficiency. The 1995
revision to the language was designed to provide greater flexibility and
extensibility, additional control over storage management and synchronization,
and standardized packages oriented toward supporting important application
areas, while at the same time retaining the original emphasis on reliability,
maintainability, and efficiency. This amended version provides further
flexibility and adds more standardized packages within the framework provided
by the 1995 revision.

!corrigendum 0.3(32)

@drepl
An enumeration type defines an ordered set of distinct enumeration literals,
for example a list of states or an alphabet of characters. The enumeration
types Boolean, Character, and Wide_Character are predefined.
@dby
An enumeration type defines an ordered set of distinct enumeration literals,
for example a list of states or an alphabet of characters. The enumeration
types Boolean, Character, Wide_Character, and Wide_Wide_Character are
predefined.

!corrigendum 0.3(34)

@drepl
Composite types allow definitions of structured objects with related
components. The composite types in the language include arrays and records. An
array is an object with indexed components of the same type. A record is an
object with named components of possibly different types. Task and protected
types are also forms of composite types. The array types String and Wide_String
are predefined.
@dby
Composite types allow definitions of structured objects with related
components. The composite types in the language include arrays and records. An
array is an object with indexed components of the same type. A record is an
object with named components of possibly different types. Task and protected
types are also forms of composite types. The array types String, Wide_String,
and Wide_Wide_String are predefined.

!corrigendum 0.3(38)

@dinsa
From any type a new type may be defined by derivation. A type, together with
its derivatives (both direct and indirect) form a derivation class. Class-wide
operations may be defined that accept as a parameter an operand of any type in
a derivation class. For record and private types, the derivatives may be
extensions of the parent type. Types that support these object-oriented
capabilities of class-wide operations and type extension must be tagged, so
that the specific type of an operand within a derivation class can be
identified at run time. When an operation of a tagged type is applied to an
operand whose specific type is not known until run time, implicit dispatching
is performed based on the tag of the operand.
@dinst
Interface types provide abstract models from which other interfaces and types
may be composed and derived. This provides a reliable form of multiple
inheritance. Interface types may also be implemented by synchronized types
(task types and protected types) thereby enabling concurrent programming and
inheritance to be merged.

!corrigendum 0.3(41)

@drepl
Representation clauses can be used to specify the mapping between types and
features of an underlying machine. For example, the user can specify that
objects of a given type must be represented with a given number of bits, or
that the components of a record are to be represented using a given storage
layout. Other features allow the controlled use of low level, nonportable, or
implementation-dependent aspects, including the direct insertion of machine
code.
@dby
Aspect clauses can be used to specify the mapping between types and
features of an underlying machine. For example, the user can specify that
objects of a given type must be represented with a given number of bits, or
that the components of a record are to be represented using a given storage
layout. Other features allow the controlled use of low level, nonportable, or
implementation-dependent aspects, including the direct insertion of machine
code.

!corrigendum 0.3(42)

@drepl
The predefined environment of the language provides for input-output and other
capabilities (such as string manipulation and random number generation) by
means of standard library packages. Input-output is supported for values of
user-defined as well as of predefined types. Standard means of representing
values in display form are also provided. Other standard library packages are
defined in annexes of the standard to support systems with specialized
requirements.
@dby
The predefined environment of the language provides for input-output and other
capabilities by
means of standard library packages. Input-output is supported for values of
user-defined as well as of predefined types. Standard means of representing
values in display form are also provided.

The predefined standard library packages provide facilities such as string
manipulation, containers of various kinds (vectors, lists, maps etc.),
mathematical functions, random number generation, and access to the
execution environment.

The specialized annexes define further predefined library packages and
facilities with emphasis on areas such as real-time scheduling,
interrupt handling, distributed systems, numerical computation, and
high-integrity systems.

!corrigendum 0.3(44)

@drepl
This International Standard replaces the first edition of 1987. In this
edition, the following major language changes have been incorporated:
@dby
This amended International Standard updates the edition of 1995 which
replaced the first edition of 1987. In the 1995 edition, the following
major language changes were incorporated:

!corrigendum 0.3(45)

@drepl
@xbullet<Support for standard 8-bit and 16-bit character sets. See Section 2,
3.5.2, 3.6.3, A.1, A.3, and A.4.>
@dby
@xbullet<Support for standard 8-bit and 16-bit characters was added. See
clauses 2.1, 3.5.2, 3.6.3, A.1, A.3, and A.4.>

!corrigendum 0.3(46)

@drepl
@xbullet<Object-oriented programming with run-time polymorphism. See the
discussions of classes, derived types, tagged types, record extensions, and
private extensions in clauses 3.4, 3.9, and 7.3. See also the new forms of
generic formal parameters that are allowed by 12.5.1, ``Formal Private and
Derived Types'' and 12.7, ``Formal Packages''.>
@dby
@xbullet<The type model was extended to include facilities for object-oriented
programming with dynamic polymorphism. See the discussions of classes, derived
types, tagged types, record extensions, and private extensions in clauses 3.4,
3.9, and 7.3. Additional forms of generic formal parameters were allowed as
described in clauses 12.5.1 and 12.7.>

!corrigendum 0.3(47)

@drepl
@xbullet<Access types have been extended to allow an access value to designate
a subprogram or an object declared by an object declaration (as opposed to just
a heap-allocated object). See 3.10.>
@dby
@xbullet<Access types were extended to allow an access value to designate a
subprogram or an object declared by an object declaration as opposed to
just an object allocated on a heap. See clause 3.10.>

!corrigendum 0.3(48)

@drepl
@xbullet<Efficient data-oriented synchronization is provided via protected
types. See Section 9.>
@dby
@xbullet<Efficient data-oriented synchronization was provided by the
introduction of protected types. See clause 9.4.>


!corrigendum 0.3(49)

@drepl
@xbullet<The library units of a library may be organized into a hierarchy of
parent and child units. See Section 10.>
@dby
@xbullet<The library structure was extended to allow library units to be
organized into a hierarchy of parent and child units. See clause 10.1.>

!corrigendum 0.3(50)

@drepl
@xbullet<Additional support has been added for interfacing to other languages.
See Annex B.>
@dby
@xbullet<Additional support was added for interfacing to other languages.
See Annex B.>

!corrigendum 0.3(51)

@drepl
@xbullet<The Specialized Needs Annexes have been added to provide specific
support for certain application areas:>
@dby
@xbullet<The Specialized Needs Annexes were added to provide specific support
for certain application areas:>

!corrigendum 0.3(57)

@drepl
@xinbull<Annex H, ``Safety and Security''>
@dby
@xinbull<Annex H, ``High Integrity Systems''>

Amendment 1 modifies the 1995 International Standard by making changes and
additions that improve the capability of the language and the reliability of
programs written in the language. In particular the changes were designed to
improve the portability of programs, interfacing to other languages, and
both the object-oriented and real-time capabilities.

The following significant changes with respect to the 1995 edition are
incorporated:

@xbullet<Support for program text is extended to cover the entire ISO/IEC
10646:2003 repertoire. Execution support now includes the 32-bit character
set. See clauses 2.1, 3.5.2, 3.6.3, A.1, A.3, and A.4.>

@xbullet<The object-oriented model has been improved by the addition of an
interface facility which provides multiple inheritance and additional
flexibility for type extensions. See clauses 3.4, 3.9, and 7.3. An
alternative notation for calling operations more akin to that used in
other languages has also been added. See clause 4.1.3.>

@xbullet<Access types have been further extended to unify properties such as
the ability to access constants and to exclude null values. See clause
3.10. Anonymous access types are now permitted more freely and anonymous
access-to-subprogram types are introduced. See clauses 3.3, 3.6, 3.10, and
8.5.1.>

@xbullet<The control of structure and visibility has been enhanced to
permit mutually dependent references between units and finer control
over access from the private part of a package. See clauses 3.10.1 and
10.1.2. In addition, limited types have been made more useful by the
provision of aggregates, constants, and constructor functions. See clauses
4.3, 6.5, and 7.5.>

@xbullet<The predefined environment has been extended to include additional time
and calendar operations, improved string handling, a comprehensive
container library, file and directory management, and access to
environment variables. See clauses 9.6.1, A.4, A.16, A.17, and A.18.>

@xbullet<Two of the Specialized Needs Annexes have been considerably enhanced:>

@xinbull<The Real-Time Systems Annex now includes the Ravenscar profile for
high-integrity systems, further dispatching policies such as Round Robin
and Earliest Deadline First, support for timing events, and support for
control of CPU time utilization. See clauses D.2, D.13, D.14, and D.15.>

@xinbull<The Numerics Annex now includes support for real and complex vectors
and matrices as previously defined in ISO/IEC 13813:1997 plus further basic
operations for linear algebra. See clause G.3.>

@xbullet<The overall reliability of the language has been enhanced by a number
of improvements. These include new syntax which detects accidental overloading,
as well as pragmas for making assertions and giving better control over the
suppression of checks. See clauses 6.1, 11.4.2, and 11.5.>

!ACATS test

Not applicable, this is just introductory material.

!appendix

*************************************************************