13.7.2 The Package System.Address_To_Access_Conversions
The following language-defined generic library package exists:
generic type Object(<>) is limited private; package System.Address_To_Access_Conversions is pragma Preelaborate(Address_To_Access_Conversions);
type Object_Pointer is access all Object; function To_Pointer(Value : Address) return Object_Pointer; function To_Address(Value : Object_Pointer) return Address;
pragma Convention(Intrinsic, To_Pointer); pragma Convention(Intrinsic, To_Address); end System.Address_To_Access_Conversions;
The To_Pointer and To_Address subprograms convert back and forth between values of types Object_Pointer and Address. To_Pointer(X'Address) is equal to X'Unchecked_Access for any X that allows Unchecked_Access. To_Pointer(Null_Address) returns null. For other addresses, the behavior is unspecified. To_Address(null) returns Null_Address (for null of the appropriate type). To_Address(Y), where Y /= null, returns Y.all'Address.
An implementation may place restrictions on instantiations of Address_To_Access_Conversions.
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Copyright © 2000 The MITRE Corporation, Inc. Ada Reference Manual