Re: [sv-ec] local/protected intermediate reference enforcement

Arturo Salz wrote:

> Gord,
> 
> I agree with your assessment. If any component along the access path is
> protected or local then access to the end-point is disallowed.


Hmmm - that is stronger than what I said.  A protected
intermediate should be allowed if the orginating reference
would be allowed access to the protected element.

So if we had:

    class D extends C;
       task foo;
          C c = new;
          c.p.pub = 1;   // c.p is protected but c.p.pub is not
       endtask;
    endclass

That should be valid since within "D" the code is permitted to
access the protected members of "C".

My original statement was that "every component along the access
path is valid to access from that point in source"; that is weaker
than "no local or protected access" but stronger than just
checking the end point.

Gord.

> 
> 	Arturo
> 
> -----Original Message-----
> From: owner-sv-ec@eda.org [mailto:owner-sv-ec@eda.org] On Behalf Of
> Gordon Vreugdenhil
> Sent: Monday, November 27, 2006 2:39 PM
> To: SV_EC List
> Subject: [sv-ec] local/protected intermediate reference enforcement 
> 
> 
> The 1800 LRM is not clear on the rules for when "local" and
> "protected" are to be enforced.  In particular, in a sequence
> of member accesses, if a middle reference would be invalid, is the
> entire reference invalid?
> 
> Example:
> 
> class P;
>     int pub;
> endclass
> 
> class C;
>     protected P p;
>     function new();
>        p = new;
>     endfunction
> endclass
> 
> module top;
>    C c = new;
>    initial begin
>       c.p.pub = 1;   // c.p is protected but c.p.pub is not
>    end
> endmodule
> 
> 
> I think that SV should be restrictive here -- an access is
> only valid from a particular point in the source if every
> component along the access path is valid to access from
> that point in source.  This is what C++ enforces as well.
> 
> Gord.

-- 
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Gordon Vreugdenhil                                503-685-0808
Model Technology (Mentor Graphics)                gordonv@model.com