Re: [sv-bc] Keywords

Clifford E. Cummings wrote:

> Hi, Kev -
>
> I think all the vendors could do as you have suggested, but most if 
> not all would prefer to have a single list of keywords.

Why do you think they would prefer a "single list"?

>
> Turns out, the biggest offender is the keyword "config," which is the 
> one we need to descend into the next level of keywords. Cadence 
> implemented most of Verilog-2001 and then got around to implementing 
> configs. Now they have the problem of customers using all types of 
> Verilog-2001 capabilities, but some of the Verilog-2001 code uses 
> "config" as an identifier, so it is not as easy as telling the tool 
> that this block of code is Verilog-1995, as I suggested in an earlier 
> email message.

 From previous e-mails it looks to me like "config" is a top-level block 
(don't have an LRM handy), in which case there is no reason to recognise 
"config" as a keyword in a module.

> One lesson to be learned from this is to create tools that flag all 
> keywords as un-implemented features so engineers don't start using 
> some keywords and later discover that additional keywords were 
> reserved but it is now difficult to separate new features from 
> recently implemented features.

That seems a bit awkward since not all possible future keywords are 
reserved anyway, and the number keeps growing.

I think limiting the scope of keywords would make life much easier for 
the committees and the users. It would be fairly simple to say that a 
BNF keyword is only recognized as a keyword in its own syntactic 
hierarchy (i.e. no change to the BNF is actually required).

Kev.

> Regards - Cliff
>
> At 12:02 AM 4/26/2005, you wrote:
>
>> Just as a matter of interest: whose compilers can't handle limited 
>> context keywords?
>>
>> I usually write recursive descent parsers that can handle tokens 
>> being keywords or
>> not depending on context. It seems that life would be easier if 
>> "keyword status"
>> could be limited to particular scopes for particular words e.g. there 
>> is no good
>> reason that keywords for configuration should have any special 
>> meaning outside of
>> a config block.
>>
>> Kev.
>
>
> ----------------------------------------------------
> Cliff Cummings - Sunburst Design, Inc.
> 14314 SW Allen Blvd., PMB 501, Beaverton, OR 97005
> Phone: 503-641-8446 / FAX: 503-641-8486
> cliffc@sunburst-design.com / www.sunburst-design.com
> Expert Verilog, SystemVerilog, Synthesis and Verification Training
>
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