[Zope-dev] Bug in ZTUtil.Batch solved

[Andreas Jung]

Please submit the patch (+ unittest) to the bug collector. Otherwise it 
might get lost.

-aj

--On Montag, 22. März 2004 13:09 Uhr +0100 AP Meyer <a.p.meyer at fel.tno.nl> 
wrote:

> Hi Zopers
>
> It seems that there is a bug in ZTUtil.Batch: when the batch should be
> the length of the batch and there are exactly as many orphans as there
> would fit on one page the length of the batch becomes size instead of
> size+orphans.
>
> Here are the numbers:
>
>
> no of
> batches    start    end    orphan    length    sequence_length
> 1          1        12     3         12        12
> 1          1        10     3         10        13      <<< WRONG *
> 2          1        10     3         10        14
>
> * end and length should be 13 in this case, 3 items are omitted
>
> 	length=12	length=13	length=14
> 	 1		 1		 1
> 	 2		 2		 2
> 	 3		 3		 3
> 	 4		 4		 4
> 	 5		 5		 5
> 	 6		 6		 6
> 	 7		 7		 7
> 	 8		 8		 8
> 	 9		 9		 9
> 	10		10		10
> 	11				11 | second batch
> 	12				12 |
> 					13 |
> 					14 |
>
>
> So, there is a jump on the edge where there should be one batch of the
> length sequence_length == length+orphans. At that point 3 (in the above
> case) items disappear.
> I have looked at the code in ZTUtils.Batch.py and found the following
> solution (line 109):
>
>  94	def opt(start,end,size,orphan,sequence):
>  95	    if size < 1:
>  96	        if start > 0 and end > 0 and end >= start:
>  97	            size=end+1-start
>  98	        else: size=7
>  99	
> 100	    if start > 0:
> 101	
> 102	        try: sequence[start-1]
> 103	        except IndexError: start=len(sequence)
> 104		
> 105	        if end > 0:
> 106	            if end < start: end=start
> 107	        else:
> 108	            end=start+size-1
> 109	            #try: sequence[end+orphan-1]
> 110	            try: sequence[end+orphan]	     # replace above with this
> 111	            except IndexError: end=len(sequence)
> 112	        ...
>
> Can somebody confirm that this solution is correct and modify it in the
> CVS, please?
>
>
> NB This has been run in Zope 2.7 with Python 2.3.3.
>
>
> thanks
> Andre