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13.11.3 Pragma Controlled

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Pragma Controlled is used to prevent any automatic reclamation of storage (garbage collection) for the objects created by allocators of a given access type. 

Syntax

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The form of a pragma Controlled is as follows: 
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  pragma Controlled(first_subtype_local_name);

Legality Rules

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The first_subtype_local_name of a pragma Controlled shall denote a non-derived access subtype. 

Static Semantics

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A pragma Controlled is a representation pragma that specifies the controlled aspect of representation.
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Garbage collection is a process that automatically reclaims storage, or moves objects to a different address, while the objects still exist. 
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If a pragma Controlled is specified for an access type with a standard storage pool, then garbage collection is not performed for objects in that pool. 

Implementation Permissions

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An implementation need not support garbage collection, in which case, a pragma Controlled has no effect. 
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