Re: clarification on +: and -: operators

From: Dennis Marsa (drm@xilinx.com)
Date: Wed May 01 2002 - 15:45:19 PDT


Precedence: bulk

Paul Graham wrote:
>
> Precedence: bulk
>
> I would like to clarify whether the +: and -: operators are single tokens or
> pairs of tokens. This affects whether a space may appear between the
> characters + and :, and whether it can be constructed out of a pair
> of macros:
>
> `define x +
> `define y :
>
> A[i `x`y 4] // legal??
>
> I would vote in favor of making each of +: and -: into a single
> two-character token, not a pair of one-character tokens.
>
> Paul

On a related note, how many tokens make up the implicit event
controls?

  @* 1 or 2?
  @(*) 1 or 4? ( or maybe 3? )

On one hand, a thread Paul started (Subject: amusing grammar ambiguity)
in September 2001 discussed this issue briefly and indicated that they
should not be considered single tokens, but also noting the complication
with respect to the (* token.

On the other hand, Stuart's book "Verilog-2001: A Guide to the New Language
Features...", describes @* and @(*) as "special tokens" in Chapter 11.

Neither the standard, nor Stuart's book shows any examples with
whitespace/comments within either @* or @(*).

Dennis Marsa
Xilinx, Inc.



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