Qualified Expression
Used to define the type of an expression where otherwise the type would be
ambiguous.
Syntax
{either}
TypeName'(Expression)
TypeName'Aggregate
Where
See Expression
Rules
The Expression or Aggregate must be compatible with the TypeName; a
qualified expression is not a type conversion!
Tips
Use a qualified expression when the compiler gives an error indicating that
the type of an expression is ambiguous. This can occur when calling
overloaded functions and procedures (e.g. (1) and (2) below), and when
constructing aggregates (e.g. (3) and (4) below).
Example
subtype T is STD_LOGIC_VECTOR(1 to 2);
...
if U > UNSIGNED'("10000000") then -- (1)
WRITE (L, STRING'("Hello")); -- (2)
V := (others => T'(others => '1')); -- (3)
case T'(A, B) is -- (4)
See Also
Aggregate, Expression, Type Conversion, TEXTIO
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