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Ada Programming/Attributes

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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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