Re: [sv-ec] 1447 updated

Hi Mike,

Attached is my feedback on the proposal for 1447.

I hope that others start reviewing this writeup since it takes
a fair amount of time to work through all of it. There is no way
that we will be able to go through it in a conference call, it would
take way too much time for that.

Neil



Michael Burns wrote On 11/28/07 05:49 PM,:
> Hi folks,
> 
> I've uploaded the latest revision of the proposal for 1447:
> 
> http://www.eda-stds.org/mantis/file_download.php?file_id=2866&type=bug
> 
> In addition to Shalom's issues, it also contains updates about queues 
> related to 1702. Hopefully the two are now de-entangled.
> 
> --Mike
> 
> 




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1. Page 1, 7.4

   There is a problem with the wording in the following sentence. The issue is 
   that an array has to have at least one dimension. I think that most people 
   will understand what you currently have here, but we may want to re-word it 
   to be more precise.

   From: "An array may have any number of unpacked dimensions."
     To:  An array may have one or more unpacked dimensions. 

2. Page 2, example at the top of the page

   The following line seems to have a typo in it. 
   Shouldn't the first ";" be a ","?

   From: int A[2][3][4], B[2][3][4]; C[5][4];
     To: int A[2][3][4], B[2][3][4], C[5][4];

3. Page 2, 7.5

   Typo: There is an extra period after [] in the next to last sentence. 

4. Page 2, 7.5

   The new text has the following: 

      "The syntax to declare a dynamic array is as follows:

	     data_type array_name index_list;

       where data_type is the data type of the array elements and index_list 
       contains one or more dynamic dimensions, each indicated by []."

   Unfortunately this is now a bit inconsistent with the previous paragraph 
   which defines a dynamic array as the following. We only have a dynamic
   array if the slowest varying dimension is dynamic.

       "If a dynamic dimension is the most slowly varying dimension, the 
	entire array is a dynamic array. A dynamic dimension in any other 
	position defines a dynamic subarray"

   One possible way to correct this would be to use the following:

       "The syntax to declare a dynamic array is as follows:

	     data_type array_name [] [index_list];   

        where data_type is the data type of the array elements and index_list 
        contains one or more additional dimensions. A dynamic dimension is 
        specified using []."

5. Dynamic dimension versus dynamic array dimension

   The proposal uses both of the following terms in many places. 
      dynamic dimension
      dynamic array dimension

   Shouldn't one term be used consistently throughout? 

6. Page 4, Syntax 5-1

   I assume that you intend to retain the "box" showing the grammar productions.
   There should be at least a one-liner shown here, so that the Editor will
   know where to place it with respect to the new text. 

7. Page 4, redundant sentence can be removed, see Mantis 2176

   The Champions flagged an issue with the text in the next to the last 
   paragraph. See mantis 2176. The first sentence of this paragraph can 
   be removed. 

8. Question 

   Can part of a multidimensional array be assigned to before all dimensions 
   have been constructed? The example in the middle of page 5 shows this.

9. Page 5, initialization expressions that contain dynamic dimensions

   "When an initialization expression contains dynamic dimensions that vary 
    more rapidly than the dimension the new constructor is sizing, the 
    corresponding dimensions in the left-hand side array or subarray adopt 
    those sizes."

   This appears to be an enhancement. As written, this behavior is 
   underspecified. The most obvious problem case occurs when the array on 
   the LHS has dynamic dimensions in different places than those which 
   occur in the expression on the RHS. It was my understanding that this
   initialization process was only meant to occur on the most rapidly varying 
   dimension. I suspect that this new enhancement will be more of a problem
   than a help at this point. 

10. Resizing dynamic dimensions - page 5, paragraph below the first example

   "Resizing a dimension is destructive, so no data from a dimension's 
    previous sizing operations is saved for user access."

    As I understand it, the data is lost for the resized dimension and any
    corresponding more rapidly varying dimensions. For multidimensional arrays
    it is possible to resize portions of the array while retaining the 
    current data for other portions. I'm not sure that this is clear in 
    the proposal. More examples might help in this regard.

11. Page 5, paragraph below the 2nd set of examples

    "Dynamic array element values are set when a legal initialization 
     expression contains them or when they receive default values."

    This sentence isn't too clear about the non-default case. The portion that
    is unclear is "when a legal initialization expression contains them".

12. 7.5.2 Size()

    There isn't anything in the proposal about 7.5.2 but now that I read
    through the proposal it makes we wonder about the built-in methods for 
    arrays that have dynamic dimensions but have a fixed sized slowest 
    varying dimension. The proposal refers to these as dynamic sub-arrays.
    This creates the need for some changes to the descriptions of the 
    built-in methods. 

    From: "The size() method returns the current size of a dynamic array or 
	   returns zero if the array has not been created."
      To: "The size() method returns the current size of a dynamic dimension or 
	   returns zero if the dynamic dimension has not been created."
   
13. 7.5.3 Delete()

    From: "The delete() method empties the array, resulting in a zero-sized 
	   array."
      To: "The delete() method empties the dynamic dimension, resulting in a 
	   zero-sized dynamic subarray."

14. Page 6, last paragraph, 2nd bullet

    From: "If a fixed dimension in the source array..."
      To: "If a fixed-size dimension in the source array..."

15. Page 7, examples

    int D [3][][]; // multiple dynamic dimensions
    D[3] = new [2]; // initialize slowest varying dynamic dimension (see 7.5.1);
    D[3][0] = new [100];
    A = D[3]; // A[0:1][100:1] and subarray D[3][0:1][0:99] both ...

    1) Array D ranges from 0:2, "D[3] = " is not valid.
    2) "D[3][0] =" is not valid.
    3) "A = D[3];" is not valid.

16. Page 7, range specification for dynamic dimension sized by new()

    It appears that the only place where the range specification created by
    new() is described is within the examples on page 7. There should be a 
    description of this in 7.5.1

17. Page 9, A.10, item 40. 

    The example in the middle of page 5 violates the restriction of this 
    footnote.

    int isrc[][][], idest[][][];
    isrc = new [2];
    isrc[0] = new [3];
    isrc[1] = new [5];
    idest = new [2] (isrc); // set size for idest[0] = 3 and for idest[1] = 5

18. Page 9, A.10, item 41. 

    I have no idea what this is trying to say.