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------------------------------------------------------------------------------
-- --
-- GNAT RUN-TIME COMPONENTS --
-- --
-- A D A . E N V I R O N M E N T _ V A R I A B L E S --
-- --
-- S p e c --
-- --
-- This specification is derived from the Ada Reference Manual for use with --
-- GNAT. In accordance with the copyright of that document, you can freely --
-- copy and modify this specification, provided that if you redistribute a --
-- modified version, any changes that you have made are clearly indicated. --
-- --
------------------------------------------------------------------------------
-- The implementation of this package is as defined in the Ada 2012 RM, but
-- it is available in Ada 95 and Ada 2005 modes as well.
package Ada.Environment_Variables is
pragma Preelaborate (Environment_Variables);
function Value (Name : String) return String;
-- If the external execution environment supports environment variables,
-- then Value returns the value of the environment variable with the given
-- name. If no environment variable with the given name exists, then
-- Constraint_Error is propagated. If the execution environment does not
-- support environment variables, then Program_Error is propagated.
function Value (Name : String; Default : String) return String;
-- If the external execution environment supports environment variables and
-- an environment variable with the given name currently exists, then Value
-- returns its value; otherwise, it returns Default.
function Exists (Name : String) return Boolean;
-- If the external execution environment supports environment variables and
-- an environment variable with the given name currently exists, then
-- Exists returns True; otherwise it returns False.
procedure Set (Name : String; Value : String);
-- If the external execution environment supports environment variables,
-- then Set first clears any existing environment variable with the given
-- name, and then defines a single new environment variable with the given
-- name and value. Otherwise Program_Error is propagated.
--
-- If implementation-defined circumstances prohibit the definition of an
-- environment variable with the given name and value, then exception
-- Constraint_Error is propagated.
--
-- It is implementation defined whether there exist values for which the
-- call Set (Name, Value) has the same effect as Clear (Name).
procedure Clear (Name : String);
-- If the external execution environment supports environment variables,
-- then Clear deletes all existing environment variables with the given
-- name. Otherwise Program_Error is propagated.
procedure Clear;
-- If the external execution environment supports environment variables,
-- then Clear deletes all existing environment variables. Otherwise
-- Program_Error is propagated.
procedure Iterate
(Process : not null access procedure (Name, Value : String));
-- If the external execution environment supports environment variables,
-- then Iterate calls the subprogram designated by Process for each
-- existing environment variable, passing the name and value of that
-- environment variable. Otherwise Program_Error is propagated.
end Ada.Environment_Variables;
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