Re: [sv-bc] Clarify -- questions about enumeration types

Yes, you are correct. I misread the VHDL LRM. Enumerated labels are
treated as overloaded function names who return types are the enmerated
type. Very different than SV. When you import an enumerated label from a
package in VHDL, the exception was that the name does not collide with
an already exposed name in the local scope, because the names are
overloaded.

In any case, the question remains: When inporting an enumerated type
from a package in SV, should all the enumerated labels be imported also?
So far, the prevailing opinion is that yes they should be imported.

Dave

Francoise Martinolle wrote:

> I don't know which kind of vhdl exception you are talking about.
> Importing only the enumeration type in VHDL does not import
> automatically the enumeration constants.
>
> I ran the example below and I get an error for undeclared identifier
> for BLUE.
>
> package my_types is
> type my_enum is (BLUE, RED, YELLOW);
> end my_types;
>
> library ieee;
> use ieee.std_logic_1164.all;
> entity e is
> port (clk: in std_logic);
> end e;
>
> use WORK.my_types.my_enum;
> architecture a of e is
> signal s : my_enum;
> begin
> p1: process (clk)
> begin
> s <= BLUE;
> end process;
> end a;
>
> ncvhdl test.v
> ncvhdl: xxxxxx (c) Copyright 1995-2004 Cadence Design Systems, DEBUG
> s <= BLUE;
> |
> ncvhdl_p: *E,IDENTU (test.v,17|16): identifier (BLUE) is not declared
> [10.3].
>
> Additionnally in VHDL enumeration literals are overloaded (unlike in
> SV), the effect of this is that if you specify the import of an
> enumeration literal that it overloaded, all of the enumeration
> literals of that name will be be made visible. The context of their
> use will determine which enum literal it is refering to. (See Jay
> example).
>
> Francoise
> '
> At 07:49 PM 6/22/2004 -0400, Steven Sharp wrote:
>
>> Dave,
>>
>> I think your answer resolved my question about structs nicely. Their
>> field
>> names don't need to be imported into the local scope when a struct
>> type or
>> variable gets imported, because a reference to them is regarded like a
>> hierarchical reference into the subscope "inside" the struct. I
>> should have
>> realized that myself.
>>
>> So it appears that importing a name only imports that name itself, and
>> that this does not cause a problem for structs.
>>
>> However, this still leaves the issue with enum literals. One would
>> expect
>> that importing an enum type would provide access to the enum literals
>> also.
>> It would be very inconvenient to have to import all of the literal names
>> individually. From what you have said, VHDL makes a special
>> exception for
>> these.
>>
>> Steven Sharp
>> sharp@cadence.com
>
>
>

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