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J.7 At Clauses


at_clause ::= for direct_name use at expression;

Static Semantics

An at_clause of the form “for x use at y;” is equivalent to an attribute_definition_clause of the form “for x'Address use y;”. 
Reason: The preferred syntax for specifying the address of an entity is an attribute_definition_clause specifying the Address attribute. Therefore, the special-purpose at_clause syntax is now obsolete.
The above equivalence implies, for example, that only one at_clause is allowed for a given entity. Similarly, it is illegal to give both an at_clause and an attribute_definition_clause specifying the Address attribute. 

Extensions to Ada 83

{extensions to Ada 83} We now allow to define the address of an entity using an attribute_definition_clause. This is because Ada 83's at_clause is so hard to remember: programmers often tend to write “for X'Address use...;”. 

Wording Changes from Ada 83

Ada 83's address_clause is now called an at_clause to avoid confusion with the new term “Address clause” (that is, an attribute_definition_clause for the Address attribute). 

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