Ada Programming/Attributes

Attributes __TOC__ When entities like variables or subprograms are declared, certain properties thereof normally are left to the compiler to specify (like the size or the address of a variable, the calling convention of a subprogram). Properties which may be queried are called Attributes; those which may be specified are called Aspects. Aspects and attributes are defined in the Ada Reference Manual annex K Language-Defined Aspects and Attributes. Language summary attributes 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 ' (apostrophe) 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 S : String := Character'(')')'Image; an especially nice parsing exercise List of language defined attributes Ada 2005 This is a new Ada 2005 attribute. Ada 2012 This is a new Ada 2012 attribute. Ada 2022 This is a new Ada 2022 attribute. Obsolescent This is a deprecated attribute and should not be used in new code. A – B 'Access 'Address 'Adjacent 'Aft 'Alignment 'Base 'Bit_Order 'Body_Version C 'Callable 'Caller 'Ceiling 'Class 'Component_Size 'Compose 'Constrained 'Copy_Sign 'Count D – F 'Definite 'Delta 'Denorm 'Digits 'Emax (Obsolescent) 'Enum_Rep (Ada 2022) 'Enum_Val (Ada 2022) 'Exponent 'External_Tag 'Epsilon (Obsolescent) 'First 'First_Bit 'Floor 'Fore 'Fraction G – L 'Has_Same_Storage (Ada 2012) 'Identity 'Image (Changed in Ada 2022) 'Index (Ada 2022) 'Input 'Large (Obsolescent) 'Last 'Last_Bit 'Leading_Part 'Length M 'Machine 'Machine_Emax 'Machine_Emin 'Machine_Mantissa 'Machine_Overflows 'Machine_Radix 'Machine_Rounding (Ada 2005) 'Machine_Rounds 'Mantissa (Obsolescent) 'Max 'Max_Alignment_For_Allocation (Ada 2012) 'Max_Size_In_Storage_Elements 'Min 'Mod (Ada 2005) 'Model 'Model_Emin 'Model_Epsilon 'Model_Mantissa 'Model_Small 'Modulus O – R 'Object_Size (Ada 2022) 'Old (Ada 2012) 'Output 'Overlaps_Storage (Ada 2012) 'Parallel_Reduce (Ada 2022) 'Partition_ID 'Pos 'Position 'Pred 'Preelaborate_Initialization (Ada 2022) 'Priority (Ada 2005) 'Put_Image (Ada 2022) 'Range 'Read 'Reduce (Ada 2022) 'Relative_Deadline (Ada 2022) 'Remainder 'Result (Ada 2012) 'Round 'Rounding S 'Safe_Emax (Obsolescent) 'Safe_First 'Safe_Large (Obsolescent) 'Safe_Last 'Safe_Small (Obsolescent) 'Scale 'Scaling 'Signed_Zeros 'Size 'Small 'Storage_Pool 'Storage_Size 'Stream_Size (Ada 2005) 'Succ T – V 'Tag 'Terminated 'Truncation 'Unbiased_Rounding 'Unchecked_Access 'Val 'Valid 'Value 'Version W – Z 'Wide_Image (Changed in Ada 2022) 'Wide_Value 'Wide_Wide_Image (Ada 2005, changed in Ada 2022) 'Wide_Wide_Value (Ada 2005) 'Wide_Wide_Width (Ada 2005) 'Wide_Width 'Width 'Write List of implementation defined attributes 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"4.2 ICC-Defined Attributes", ICC Ada Implementation Reference — ICC Ada Version 8.2.5 for i960MC Targets, document version 2.11.4 of the Irvine ICC compiler. PowerAda Implementation-defined attribute of OC Systems' PowerAda. SPARCompiler Implementation-defined attribute of Sun's SPARCompiler Ada. A – D 'Abort_Signal (GNAT) 'Address_Size (GNAT) 'Architecture (ICC) 'Asm_Input (GNAT) 'Asm_Output (GNAT) 'AST_Entry (GNAT, HP Ada) 'Atomic_Always_Lock_Free (GNAT) 'Bit (GNAT, HP Ada) 'Bit_Position (GNAT) 'CG_Mode (ICC) 'Code_Address (GNAT) 'Compiler_Key (SPARCompiler) 'Compiler_Version (GNAT, SPARCompiler) 'Constrained (GNAT) 'Declared (ICC) 'Default_Bit_Order (GNAT) 'Default_Scalar_Storage_Order (GNAT) 'Deref (GNAT) 'Descriptor_Size (GNAT) 'Dope_Address (SPARCompiler) 'Dope_Size (SPARCompiler) E – H 'Elaborated (GNAT) 'Elab_Body (GNAT) 'Elab_Spec (GNAT) 'Elab_Subp_Body (GNAT) 'Emax (GNAT) 'Enabled (GNAT) 'Entry_Number (SPARCompiler) 'Enum_Rep (GNAT) 'Enum_Val (GNAT) 'Epsilon (GNAT) 'Exception_Address (ICC) 'Extended_Aft (PowerAda) 'Extended_Base (PowerAda) 'Extended_Digits (PowerAda) 'Extended_Fore (PowerAda) 'Extended_Image (PowerAda) 'Extended_Value (PowerAda) 'Extended_Width (PowerAda) 'Extended_Wide_Image (PowerAda) 'Extended_Wide_Value (PowerAda) 'Extended_Wide_Width (PowerAda) 'Fast_Math (GNAT) 'Finalization_Size (GNAT) 'Fixed_Value (GNAT) 'From_Any (GNAT) 'Has_Access_Values (GNAT) 'Has_Discriminants (GNAT) 'Has_Tagged_Values (GNAT) 'High_Word (ICC) 'Homogeneous (SPARCompiler) I – N 'Img (GNAT) 'Initialized (GNAT) 'Integer_Value (GNAT) 'Invalid_Value (GNAT) 'Linear_Address (ICC) 'Large (GNAT) 'Library_Level (GNAT) 'Low_Word (ICC) 'Loop_Entry (GNAT) 'Machine_Size (GNAT, HP Ada) 'Mantissa (GNAT) 'Max_Integer_Size (GNAT) 'Max_Interrupt_Priority (GNAT) 'Max_Priority (GNAT) 'Maximum_Alignment (GNAT) 'Mechanism_Code (GNAT) 'Null_Parameter (GNAT, HP Ada) O – T 'Object_Size (GNAT) 'Old (GNAT) 'Passed_By_Reference (GNAT) 'Pool_Address (GNAT) 'Range_Length (GNAT) 'Ref (SPARCompiler) 'Restriction_Set (GNAT) 'Result (GNAT) 'Round (GNAT) 'Safe_Emax (GNAT) 'Safe_Large (GNAT) 'Safe_Small (GNAT) 'Scalar_Storage_Order (GNAT) 'Simple_Storage_Pool (GNAT) 'Small (GNAT) 'Small_Denominator (GNAT) 'Small_Numerator (GNAT) 'Storage_Unit (GNAT) 'Stub_Type (GNAT) 'System_Allocator_Alignment (GNAT) 'Target (ICC) 'Target_Name (GNAT) 'Task_ID (SPARCompiler) 'Tick (GNAT) 'To_Address (GNAT) 'To_Any (GNAT) 'Type_Class (GNAT, HP Ada) 'TypeCode (GNAT) 'Type_Key (SPARCompiler) U – Z 'UET_Address (GNAT) 'Unconstrained_Array (GNAT) 'Universal_Literal_String (GNAT) 'Unrestricted_Access (GNAT, ICC) 'Update (GNAT) 'VADS_Size (GNAT) 'Valid_Value (GNAT) 'Valid_Scalars (GNAT) 'Value_Size (GNAT) 'Wchar_T_Size (GNAT) 'Word_Size (GNAT) See also Wikibook Ada Programming Ada Programming/Aspects Ada Programming/Pragmas Ada Programming/Keywords Ada Reference Manual Ada 83 4 1 4 Attributes A Predefined Language Attributes Ada 95 4 1 4 Attributes K (informative) Language-Defined Attributes Ada 2005 4 1 4 Attributes K (informative) Language-Defined Attributes Ada 2012 4 1 4 Attributes K (informative) Language-Defined Aspects and Attributes Ada 2022 4 1 4 Attributes K (informative) Language-Defined Aspects and Attributes References Attributes es:Programación en Ada/Atributos