ISO/IEC 8652:2012

Information technology — Programming languages — Ada

ISO/IEC 8652:2012 specifies the form and meaning of programs written in the programming language Ada. Its purpose is to promote the portability of Ada programs to a variety of computing systems. This third edition of ISO/IEC 8652 focuses on improvements in those user domains where safety and criticality are prime concerns. It enhances the functionality of containers, improves the ability to write and enforce contracts for Ada entities (for instance, via preconditions), and adds to the capabilities of Ada to perform on multicore and multithreaded architectures. Ada is designed to support the construction of long‐lived, highly reliable software systems. The language includes facilities to define packages of related types, objects, and operations. The packages may be parameterized and the types may be extended to support the construction of libraries of reusable, adaptable software components. The operations may be implemented as subprograms using conventional sequential control structures, or as entries that include synchronization of concurrent threads of control as part of their invocation. Ada supports object‐oriented programming by providing classes and interfaces, inheritance, polymorphism of variables and methods, and generic units. The language treats modularity in the physical sense as well, with a facility to support separate compilation. The language provides rich support for real‐time, concurrent programming, and includes facilities for multicore and multiprocessor programming. Errors can be signaled as exceptions and handled explicitly. The language also covers systems programming; this requires precise control over the representation of data and access to system‐dependent properties. Finally, a predefined environment of standard packages is provided, including facilities for, among others, input‐output, string manipulation, numeric elementary functions, random number generation, and definition and use of containers. Foremost in the design of Ada is the intent to increase the reliability of programs by compiletime checking and rejection of unsafe programs.

Technologies de l'information — Langages de programmation — Ada

General Information

• Status: Withdrawn
• Publication Date: 09-Dec-2012
• ICS: 35.060 - Languages used in information technology
• Technical Committee: ISO/IEC JTC 1/SC 22 - Programming languages, their environments and system software interfaces
• Drafting Committee: ISO/IEC JTC 1/SC 22/WG 9 - Ada
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 02-May-2023

Relations

• Revised: ISO/IEC 8652:2023 - Information technology — Programming languages — Ada
• Effective Date: 26-Nov-2021
• Revises: ISO/IEC 8652:1995/Amd 1:2007 - Information technology — Programming languages — Ada — Amendment 1
• Effective Date: 11-Feb-2012
• Revises: ISO/IEC 8652:1995 - Information technology — Programming languages — Ada
• Effective Date: 11-Feb-2012

Standards Content (Sample)

INTERNATIONAL ISO/IEC
STANDARD 8652
Third edition
2012-12-15


Information technology — Programming
languages — Ada
Technologies de l'information — Langages de programmation — Ada




Reference number
ISO/IEC 8652:2012(E)
©
ISO/IEC 2012

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ISO/IEC 8652:2012(E)

COPYRIGHT PROTECTED DOCUMENT


©  ISO/IEC 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
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Published in Switzerland

ii © ISO/IEC 2012 – All rights reserved

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ISO/IEC 8652:2012(E)
Table of Contents
Table of Contents.i
Foreword .xi
Introduction.xii
1  General .1
1.1 Scope . 1
1.1.1 Extent. 1
1.1.2 Structure.2
1.1.3 Conformity of an Implementation with the Standard . 4
1.1.4 Method of Description and Syntax Notation. 5
1.1.5 Classification of Errors . 6
1.2 Normative References. 7
1.3 Terms and Definitions . 8
2  Lexical Elements.9
2.1 Character Set .9
2.2 Lexical Elements, Separators, and Delimiters . 11
2.3 Identifiers. 12
2.4 Numeric Literals. 13
2.4.1 Decimal Literals. 13
2.4.2 Based Literals. 13
2.5 Character Literals . 14
2.6 String Literals.14
2.7 Comments . 15
2.8 Pragmas. 15
2.9 Reserved Words . 17
3  Declarations and Types.19
3.1 Declarations . 19
3.2 Types and Subtypes. 20
3.2.1 Type Declarations. 21
3.2.2 Subtype Declarations. 23
3.2.3 Classification of Operations. 24
3.2.4 Subtype Predicates . 24
3.3 Objects and Named Numbers. 26
3.3.1 Object Declarations. 28
3.3.2 Number Declarations . 31
3.4 Derived Types and Classes . 31
3.4.1 Derivation Classes . 34
3.5 Scalar Types. 35
3.5.1 Enumeration Types . 40
3.5.2 Character Types . 41
3.5.3 Boolean Types . 42
3.5.4 Integer Types . 42
3.5.5 Operations of Discrete Types. 44
3.5.6 Real Types. 45
3.5.7 Floating Point Types . 46
3.5.8 Operations of Floating Point Types. 48
3.5.9 Fixed Point Types. 48
3.5.10 Operations of Fixed Point Types . 50
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ISO/IEC 8652:2012(E)
3.6 Array Types.51
3.6.1 Index Constraints and Discrete Ranges .54
3.6.2 Operations of Array Types .55
3.6.3 String Types.56
3.7 Discriminants.56
3.7.1 Discriminant Constraints.59
3.7.2 Operations of Discriminated Types.60
3.8 Record Types.60
3.8.1 Variant Parts and Discrete Choices.62
3.9 Tagged Types and Type Extensions.64
3.9.1 Type Extensions.67
3.9.2 Dispatching Operations of Tagged Types .68
3.9.3 Abstract Types and Subprograms.71
3.9.4 Interface Types.72
3.10 Access Types.75
3.10.1 Incomplete Type Declarations .77
3.10.2 Operations of Access Types .79
3.11 Declarative Parts .85
3.11.1 Completions of Declarations.85
4  Names and Expressions .87
4.1 Names.87
4.1.1 Indexed Components.88
4.1.2 Slices.89
4.1.3 Selected Components.89
4.1.4 Attributes .91
4.1.5 User-Defined References.92
4.1.6 User-Defined Indexing .93
4.2 Literals.95
4.3 Aggregates.96
4.3.1 Record Aggregates .96
4.3.2 Extension Aggregates .98
4.3.3 Array Aggregates .99
4.4 Expressions .102
4.5 Operators and Expression Evaluation .103
4.5.1 Logical Operators and Short-circuit Control Forms .104
4.5.2 Relational Operators and Membership Tests .105
4.5.3 Binary Adding Operators.109
4.5.4 Unary Adding Operators.110
4.5.5 Multiplying Operators .110
4.5.6 Highest Precedence Operators.112
4.5.7 Conditional Expressions .113
4.5.8 Quantified Expressions .114
4.6 Type Conversions .115
4.7 Qualified Expressions.119
4.8 Allocators .120
4.9 Static Expressions and Static Subtypes .122
4.9.1 Statically Matching Constraints and Subtypes .125
5  Statements . 127
5.1 Simple and Compound Statements - Sequences of Statements .127
5.2 Assignment Statements.128
5.3 If Statements .129
5.4 Case Statements.130
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ISO/IEC 8652:2012(E)
5.5 Loop Statements. 131
5.5.1 User-Defined Iterator Types . 133
5.5.2 Generalized Loop Iteration . 134
5.6 Block Statements. 136
5.7 Exit Statements. 137
5.8 Goto Statements . 137
6  Subprograms.139
6.1 Subprogram Declarations. 139
6.1.1 Preconditions and Postconditions . 142
6.2 Formal Parameter Modes. 144
6.3 Subprogram Bodies . 145
6.3.1 Conformance Rules. 146
6.3.2 Inline Expansion of Subprograms . 148
6.4 Subprogram Calls. 148
6.4.1 Parameter Associations. 150
6.5 Return Statements. 153
6.5.1 Nonreturning Procedures . 155
6.6 Overloading of Operators . 156
6.7 Null Procedures . 157
6.8 Expression Functions . 158
7  Packages .159
7.1 Package Specifications and Declarations. 159
7.2 Package Bodies . 160
7.3 Private Types and Private Extensions. 161
7.3.1 Private Operations. 163
7.3.2 Type Invariants . 165
7.4 Deferred Constants . 167
7.5 Limited Types. 168
7.6 Assignment and Finalization . 170
7.6.1 Completion and Finalization. 172
8  Visibility Rules .175
8.1 Declarative Region . 175
8.2 Scope of Declarations . 176
8.3 Visibility . 177
8.3.1 Overriding Indicators . 179
8.4 Use Clauses . 180
8.5 Renaming Declarations. 181
8.5.1 Object Renaming Declarations . 182
8.5.2 Exception Renaming Declarations . 183
8.5.3 Package Renaming Declarations . 183
8.5.4 Subprogram Renaming Declarations . 184
8.5.5 Generic Renaming Declarations . 186
8.6 The Context of Overload Resolution. 186
9  Tasks and Synchronization.189
9.1 Task Units and Task Objects. 189
9.2 Task Execution - Task Activation. 192
9.3 Task Dependence - Termination of Tasks. 193
9.4 Protected Units and Protected Objects . 194
9.5 Intertask Communication. 197
9.5.1 Protected Subprograms and Protected Actions. 199
9.5.2 Entries and Accept Statements. 200
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ISO/IEC 8652:2012(E)
9.5.3 Entry Calls.203
9.5.4 Requeue Statements.205
9.6 Delay Statements, Duration, and Time .207
9.6.1 Formatting, Time Zones, and other operations for Time.209
9.7 Select Statements.215
9.7.1 Selective Accept.215
9.7.2 Timed Entry Calls .217
9.7.3 Conditional Entry Calls.218
9.7.4 Asynchronous Transfer of Control.219
9.8 Abort of a Task - Abort of a Sequence of Statements.220
9.9 Task and Entry Attributes.221
9.10 Shared Variables .222
9.11 Example of Tasking and Synchronization.223
10  Program Structure and Compilation Issues. 225
10.1 Separate Compilation.225
10.1.1 Compilation Units - Library Units .225
10.1.2 Context Clauses - With Clauses .228
10.1.3 Subunits of Compilation Units.230
10.1.4 The Compilation Process .232
10.1.5 Pragmas and Program Units .233
10.1.6 Environment-Level Visibility Rules .234
10.2 Program Execution.234
10.2.1 Elaboration Control.236
11  Exceptions . 241
11.1 Exception Declarations.241
11.2 Exception Handlers .242
11.3 Raise Statements.243
11.4 Exception Handling .243
11.4.1 The Package Exceptions .244
11.4.2 Pragmas Assert and Assertion_Policy .246
11.4.3 Example of Exception Handling.248
11.5 Suppressing Checks .249
11.6 Exceptions and Optimization .252
12  Generic Units . 253
12.1 Generic Declarations.253
12.2 Generic Bodies .255
12.3 Generic Instantiation.256
12.4 Formal Objects .258
12.5 Formal Types .259
12.5.1 Formal Private and Derived Types .261
12.5.2 Formal Scalar Types .263
12.5.3 Formal Array Types.263
12.5.4 Formal Access Types .264
12.5.5 Formal Interface Types .265
12.6 Formal Subprograms .265
12.7 Formal Packages .267
12.8 Example of a Generic Package .269
13  Representation Issues . 273
13.1 Operational and Representation Aspects .273
13.1.1 Aspect Specifications.276
13.2 Packed Types.278
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ISO/IEC 8652:2012(E)
13.3 Operational and Representation Attributes . 279
13.4 Enumeration Representation Clauses. 285
13.5 Record Layout. 286
13.5.1 Record Representation Clauses . 286
13.5.2 Storage Place Attributes. 288
13.5.3 Bit Ordering. 289
13.6 Change of Representation . 290
13.7 The Package System . 291
13.7.1 The Package System.Storage_Elements . 293
13.7.2 The Package System.Address_To_Access_Conversions. 294
13.8 Machine Code Insertions . 294
13.9 Unchecked Type Conversions. 295
13.9.1 Data Validity. 296
13.9.2 The Valid Attribute. 297
13.10 Unchecked Access Value Creation. 298
13.11 Storage Management . 298
13.11.1 Storage Allocation Attributes. 301
13.11.2 Unchecked Storage Deallocation. 302
13.11.3 Default Storage Pools . 303
13.11.4 Storage Subpools. 304
13.11.5 Subpool Reclamation. 306
13.11.6 Storage Subpool Example . 307
13.12 Pragma Restrictions and Pragma Profile . 309
13.12.1 Language-Defined Restrictions and Profiles. 310
13.13 Streams. 312
13.13.1 The Package Streams . 312
13.13.2 Stream-Oriented Attributes . 313
13.14 Freezing Rules . 318
The Standard Libraries.321
Annex A (normative) Predefined Language Environment .323
A.1 The Package Standard. 326
A.2 The Package Ada . 330
A.3 Character Handling . 330
A.3.1 The Packages Characters, Wide_Characters, and Wide_Wide_Characters 330
A.3.2 The Package Characters.Handling. 331
A.3.3 The Package Characters.Latin_1. 333
A.3.4 The Package Characters.Conversions . 338
A.3.5
...

INTERNATIONAL ISO/IEC
STANDARD 8652
Third edition
2012-12-15

Information technology — Programming
languages — Ada
Technologies de l'information — Langages de programmation — Ada



Reference number
ISO/IEC 8652:2012(E)
©
ISO/IEC 2012

---------------------- Page: 1 ----------------------
ISO/IEC 8652:2012(E)


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This third edition cancels and replaces the second edition (ISO/IEC 8652:1995), which has been technically
revised. It also incorporates the Technical Corrigendum ISO/IEC 8652:1995/Cor.1:2001 and the Amendment
ISO/IEC 8652:1995/Amd.1:2007).
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ISO/IEC 8652:2012(E)
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