RE: [sv-bc] Top-25 proposed enhancement: Allow trailing commas in ANSI port / named connection lists

As discussed in

   http://www.eda.org/svdb/view.php?id=1162

From: owner-sv-bc@eda.org [mailto:owner-sv-bc@eda.org] On Behalf Of Bresticker, Shalom
Sent: Thursday, April 29, 2010 8:38 AM
To: Paul Graham
Cc: David Gates; sv-bc@eda.org
Subject: RE: [sv-bc] Top-25 proposed enhancement: Allow trailing commas in ANSI port / named connection lists

Doesn't it?

Shalom

________________________________
From: Paul Graham [mailto:pgraham@oasys-ds.com]
Sent: Thursday, April 29, 2010 6:36 PM
To: Bresticker, Shalom
Cc: David Gates; sv-bc@eda.org
Subject: Re: [sv-bc] Top-25 proposed enhancement: Allow trailing commas in ANSI port / named connection lists
Null ports are funny things. A naive parser can create a null port where none is expected. The reasoning is that since:

    module m(,,);

declares a module with three null ports, and:

    module m(,);

declares a module with two null ports, then shouldn't:

    module m();

declare a module with one null port?

Paul
----- Original Message -----
From: "Shalom Bresticker" <shalom.bresticker@intel.com>
To: "David Gates" <David.Gates@amd.com>, "sv-bc@eda.org" <sv-bc@eda.org>
Sent: Thursday, April 29, 2010 11:06:12 AM
Subject: RE: [sv-bc] Top-25 proposed enhancement: Allow trailing commas in ANSI port / named connection lists

I have another point.

Today, syntactically, trailing commas are allowed in non-ANSI style port lists.

This creates another port, a "null port", at the end.

This often creates tool problems.

I would have preferred that the comma at the end either be ignored or be a syntax error, as I have not yet heard of a use for null ports.

However, as long as they are there, I hesitate to create another syntax which is inconsistent with existing behavior.

I don't know whether eliminating null ports would create a back-compatibility problem.

I have never seen them used deliberately.

Shalom

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