Ada Programming/Keywords/for

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Contents 1 For loops 2 Representation clauses 2.1 Attribute definition clause 2.2 Enumeration representation clause 2.3 Record representation clause 2.4 At clause (obsolescent) 3 See also 3.1 Wikibook 3.2 Ada Reference Manual 3.2.1 Ada 83 3.3 Ada Quality and Style Guide 4 References

This keyword is used in:

• For loops
• Representation clauses:
  • attribute definition clause
  • enumeration representation clause
  • record representation clause
  • at clause (obsolescent)

Nowadays representation clauses are formally called aspect clauses in the last versions of the Reference Manual due to some technicalities, although representation clauses is the name far more extended among Ada programmers. As a historical note, they were known as representation specifications (rep specs) in pre-Ada 83 proposals.^[1]

[edit] For loops

[loop name :] for var in [[[Ada Programming/Keywords/reverse|reverse]]] [type range] range loop
   ...
end loop;

Where range can be:

• explicit range like "low .. high",
• range of scalar or array type: type'Range (or type'Range(n) for multidimensional array types)
• range of an array: array'Range (or array'Range(n) for multidimensional arrays)

[edit] Representation clauses

[edit] Attribute definition clause

for id'attribute use value;

Where attribute can be any specifiable attribute.

[edit] Enumeration representation clause

for enumeration type use (enum1 => value1, enum2 => value2, ...);

[edit] Record representation clause

for record type use
  record
     component1 at offset range first bit 1 .. last bit 1;
     component2 at offset range first bit 2 .. last bit 2;
     ...
  end record;

[edit] At clause (obsolescent)

At clauses are obsolescent since Ada 95:

for id use at address;

where address is of the type System.Address.

An at clause is equivalent to "for id'Address use address;". Since Ada 95 this is the preferred method.

[edit] See also

[edit] Wikibook

• Ada Programming
• Ada Programming/Keywords

[edit] Ada Reference Manual

• 2.9 Reserved Words (Annotated)
• Annex P (informative) Syntax Summary (Annotated)
• 5.5 Loop Statements (Annotated)
• 13.3 Operational and Representation Attributes (Annotated)
• 13.4 Enumeration Representation Clauses (Annotated)
• 13.5.1 Record Representation Clauses (Annotated)
• Annex J.7 At Clauses (Annotated) (obsolescent)

[edit] Ada 83

• 13.5 Address Clauses (obsolescent)

[edit] Ada Quality and Style Guide

• 3.1.3 Capitalization

[edit] References

1. ↑ John Barnes (2003-03-25). High-Integrity Software — The SPARK Approach to Safety and Security. Addison-Wesley. ISBN 0-321-13616-0. Retrieved on 2008-06-06. “Representation clauses are now strictly known as aspect clauses — the name was changed in the 2000 Corrigendum for Ada 95 for subtle reasons that need not concern us; Ada historians might recall that they were known as representation specifications (rep specs) prior to the ANSI standardization in 1983. These various terminologies are all in use and the reader will encounter them in the literature. (pp.212–213)”

Ada Keywords

abort else new return abs elsif not reverse abstract (Ada 95) end null accept entry select access exception of separate aliased (Ada 95) exit or subtype all others synchronized (Ada 2005) and for out array function overriding (Ada 2005) tagged (Ada 95) at task generic package terminate begin goto pragma then body private type if procedure case in protected (Ada 95) until (Ada 95) constant interface (Ada 2005) use is raise declare range when delay limited record while delta loop rem with digits renames do mod requeue (Ada 95) xor