Re: [sv-ec] Manti 958, 974

Hi Jonathan,

In 7.11 there is the following sentence.

   "The empty array literal {} is used to denote an empty queue. If an
    initial value is not provided in the declaration, the queue variable
    is initialized to the empty queue."

In light of this, I am having a problem understanding what you are
getting at when you mention an "uninitialized queue". Is there such a thing?


Neil






Jonathan Bromley wrote On 11/27/07 05:53 AM,:
> hi EC,
> 
> I've added a note to 974 proposing that it be closed as
> duplicating (a small part of) 1447.
> 
> 958 is a little more problematic - it asks what the .size
> method and $size() function should return when applied to
> uninitialized dynamic arrays or queues.
> 
> My personal view is that there is little point in trying 
> to distinguish between a "null" (uninitialized) queue or 
> dynamic array and one having zero size.  If dynamic array 
> and queue variables were in fact *references* to the 
> underlying array object, I'd take a very different view.
> But they're not - at least, not from the user's viewpoint.
> The tools I've tried all seem to agree with me, and 
> therefore disagree with the current LRM.
> 
> I therefore plan to write a short proposal saying that
> uninitialized queues and dynamic arrays have a .size() 
> of zero, and yield zero from the $size() system function.
> 
> However, that's not the end of it.  We also have the other
> functions $left, $right, $low, $high, $increment to consider.
> At present, 19.7 says...
> 
>    When used on a dynamic array or queue dimension, 
>    these functions return information about the 
>    current state of the array. If the dimension is 
>    currently empty, these functions shall return 
>    a 'x. 
> 
> This seems very strange for $increment, which surely
> should always return -1 for queues and dynamic arrays.
> I would also have thought that $left and $low should
> always return 0 even if the array is empty.  The 
> interesting question is whether $right/$high should
> return -1 or 'x.  If we agree that an empty queue or
> dynamic array is a legitimate object, and that an 
> uninitialized queue or dynamic array is indistinguishable
> from an empty one, then I would have thought that -1
> would make more sense.
> 
> Opinions?  Please?




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