Question on staticness of shared variable name

Folks,

While working on external names (FT-7), the following question came up. If
we want to define an alias for an external name, there is a rule that the
aliased name be static. This suggests that an external name should be
static, which seems quite reasonable. One of the things we want to be able
to reference with an external name is a shared variable, which must be of a
protected type.

However, the current rules for static names preclude a name that denotes an
object of a protected type. I can't think of a good reason why. Any ideas?

With the current rule, it would be illegal to declare an alias as follows:

  package types is
    type T is protected...end protected;
  end package types;    

  architecture a of e is
    shared variable V : work.types.T;
    alias V1 is V;
  end architecture a;

Extending this to external names, it would then be illegal to write in
another design unit:

  ...
  alias V2 is <<variable .e.V1 : work.types.T>>;
  ...

Since the only kind of variable we can denote with an external name is a
shared variable, we would never be able to legally write an external
variable name.

Wouldn't it make sense to allow a name denoting an object of protected type
to be a static name? My understanding of staticness of a name is that it
means you can statically determine what is denoted by the name. For a name
denoting a shared variable of protected type, the fact of it being of that
type doesn't affect being able to determine the denotation statically.
Further, a selected name denoting a method of the shared variable could also
be considered static. It's only a function call to the method that is not
static, and that's precluded by a prefix that is a function call being
non-static.

In summary, it would appear that the LRM writers defining protected types
didn't properly understand staticness of names when they added that rule in
6.1. Either that, or I've got it messed up in my head and need to be
straightened out. Anyone care to help me? Thanks.

Cheers,

PA

--
Dr. Peter J. Ashenden                peter@ashenden.com.au
Ashenden Designs Pty. Ltd.           www.ashenden.com.au
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