RE: [sv-ec] randomize() is virtual, but what about constraint_mode() ??

From: Jonathan Bromley <jonathan.bromley_at_.....>
Date: Sat May 24 2008 - 01:01:10 PDT
Steven,

> This came up here not too long ago, and I had not gotten around to
> bringing it up to the committee.

Thanks for the response.  Since you've already given some 
serious thought to this, it's perhaps better for you to raise
a Mantis item for it - but I'm happy to do it if you prefer.

> My interpretation of the LRM was that it does not say that 
> constraint_mode() is virtual, so it isn't, even though
> that doesn't make much sense.  The LRM should probably
> be modified to change that.

I take your point, but it's not that simple.  In the case
that I was considering, constraint_mode() is not truly a
method of the *class*, but rather a pseudo-method of the
*constraint*.  However, I suppose constraints work much
more like data members of the class than like virtual 
methods, so your interpretation is still probably right.

If so, then at least one simulator is broken, but it's 
the only one that gives desirable behaviour :-)   I guess 
I'm not too worried about it anyway.  constraint_mode() is 
an ugly thing to shoe-horn into any reasonable methodology; 
if you need it, you should have thought about putting 
appropriate control values and implication constraints 
into your class.

> Regarding your supplementary question:  Executing constraint_mode() at
> simulation time to turn off a constraint does not make the constraint
> name disappear.  It definitely does not make it disappear back during
> compilation, when names were resolved.  So no, I don't think that the
> base-class constraint would apply if the same-named derived-class
> constraint is turned off.

OK.
-- 
Jonathan Bromley, Consultant

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Received on Sat May 24 01:02:07 2008

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