Rationale for Ada 2012
9.3.1 Aggregates for private types
notation was introduced in Ada 2005 for aggregates to mean the default
value if any. A curiosity is that we can write
type Secret is private;
type Visible is
X: Visible := (A => 77; S => <>);
but we cannot write
S: Secret := <>; -- illegal
The argument is that this would be of little use
since the components take their default values anyway.
For uniformity it was
proposed that we might allow
S: Secret := (others => <>);
for private types and
also for task and protected types. One advantage would be that we could
S: constant Secret := (others => <>);
whereas it is not possible to declare a constant
of a private type because we are unable to give an initial value.
However, discussion of this issue led into a quagmire
in Ada 2005 and so was abandoned. It remains abandoned in Ada 2012!
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