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Ada Programming/Attributes

< Ada Programming

Language summary attributesEdit

The concept of attributes is pretty unique to Ada. Attributes allow you to get —and sometimes set— information about objects or other language entities such as types. A good example is the Size attribute. It describes the size of an object or a type in bits. 

A : Natural := Integer'Size; -- A is now 32 (with the GNAT compiler for the x86 architecture)

However, unlike the sizeof operator from C/C++ the Size attribute can also be set: 

type Byte is range -128 .. 127;  -- The range fits into 8 bits but the
                               -- compiler is still free to choose.
for  Byte'Size use 8;           -- Now we force the compiler to use 8 bits.

Of course not all attributes can be set. An attribute starts with a tick ' and is followed by its name. The compiler determines by context if the tick is the beginning of an attribute, a character literal or a quantified expression. 

A : Character := Character'Val (32) -- A is now a space
B : Character := ' ';               -- B is also a space

List of language defined attributesEdit

Ada 2005 
This is a new Ada 2005 attribute.
Ada 2012 
This is a new Ada 2012 attribute.
Obsolescent 
This is a deprecated attribute and should not be used in new code.

A – BEdit

CEdit

D – FEdit

G – LEdit

MEdit

O – REdit

SEdit

T – VEdit

W – ZEdit

List of implementation defined attributesEdit

The following attributes are not available in all Ada compilers, only in those that had implemented them.

Currently, there are only listed the implementation-defined attributes of a few compilers. You can help Wikibooks adding specific attributes of other compilers:

GNAT 
Implementation-defined attribute of the GNAT compiler from AdaCore/FSF.
HP Ada 
Implementation-defined attribute of the HP Ada compiler (formerly known as "DEC Ada").
ICC 
Implementation-defined attribute[1] of the Irvine ICC compiler.
PowerAda 
Implementation-defined attribute of OC Systems' PowerAda.
SPARCompiler 
Implementation-defined attribute of Sun's SPARCompiler Ada.

A – DEdit

E – HEdit

I – NEdit

O – TEdit

U – ZEdit

See alsoEdit

ReferencesEdit

  1. ↑ "4.2 ICC-Defined Attributes", ICC Ada Implementation Reference — ICC Ada Version 8.2.5 for i960MC Targets, document version 2.11.4 [1]
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