Ada Programming/Keywords/use

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Contents 1 Use clause 1.1 At library level 1.2 At declaration level 1.3 For types 2 Representation clause 2.1 For attributes 2.2 For records 2.3 For enumerations 3 See also 3.1 Wikibook 3.2 Ada Reference Manual 3.3 Ada Quality and Style Guide

[edit] Use clause

[edit] At library level

This use clause make the content of a package immediately visible.

with Ada.Text_IO;   use Ada.Text_IO;

procedure Hello is
begin
   Put_Line("Hello, world!");
   New_Line;
   Put_Line("I am an Ada program with package use.");
end Hello;

If readability is your main concern then you should avoid this type of use clause. However it is needed to resolve a name clash between the packages which are imported and the package currently compiled.

[edit] At declaration level

with Ada.Text_IO;

procedure Hello is
   use Ada.Text_IO;
begin
   Put_Line("Hello, world!");
   New_Line;
   Put_Line("I am an Ada program with package use.");
end Hello;

[edit] For types

with Ada.Text_IO;

procedure Hello is
   use type Ada.Text_IO.File_Type
begin
   Ada.Text_IO.Put_Line("Hello, world!");
   Ada.Text_IO.New_Line;
   Ada.Text_IO.Put_Line("I am an Ada program with package use.");
end Hello;

[edit] Representation clause

[edit] For attributes

type Day_Of_Month is range 1 .. 31;            
for  Day_Of_Month'Size      use 8;  -- 8 bits
for  Day_Of_Month'Alignment use 1;  -- 1 byte

[edit] For records

type Device_Register is
    record
       Ready : Status_Flag;
       Error : Error_Flag;
       Data  : Unsigned_16;
    end record;

for  Device_Register use
    record
       Ready at 0 range  0 .. 0;
       Error at 0 range  1 .. 1;
       -- Reserved bits
       Data  at 0 range 16 .. 31;
    end record;

[edit] For enumerations

type Status_Flag is  (Ready, Wait);
for  Status_Flag use (Ready => 0, Wait => 1);

[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)

• 8.3 Visibility (Annotated)
• 8.4 Use Clauses (Annotated)
• 13.3 Operational and Representation Attributes (Annotated)
• 13.4 Enumeration Representation Clauses (Annotated)
• 13.5.1 Record Representation Clauses (Annotated)

[edit] Ada Quality and Style Guide

• 3.1.3 Capitalization

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