Studio:Scl union activate

The scl_union_activate pragma

The scl_union_activate pragma provides a means to map discriminant values to specific union members. It can only apply to discriminated unions that have been identified by the scl_union pragma.

A single scl_union_activate pragma prescribes the set of values for the discriminant and the member that is active for those values.

Syntax

#pragma scl_union_activate(container-specifier, union-member-specifier, constant-value-list)

Parameters	Type	Description
container-specifier	Type	Name of the structure encapsulating the union
union-member-specifier	Member	The active member of the union
constant-value-list	Integer constant expression list	List of the constant expressions that the discriminant takes on to activate the union member identified in this pragma

Notes

• The discriminant field use in scl_union_activate must have already been identified with scl_union.

Examples

Use the following links to the scl_union page to see examples of the scl_union_activate pragma:

• Explicit mapping: Discriminant values are explicitly mapped to active union members using scl_union_activate().
• Explicit mapping of multiple discriminant values to a single active member.
• Unmapped discriminant values indicating no member is active.
• Discriminant values defined by macros.

See Also

• The scl_union pragma page.
• For additional information on the scl_union_activate pragma, including constraints, refer to the section on scl_union_activate in the SCL Reference Guide.