Re: using array slice as lvalue

[Peter Stephenson <Peter.Stephenson@xxxxxxx>]

On Tue, 21 Dec 2010 00:45:49 -0800
Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx> wrote:
> On Dec 21,  3:42pm, Le Wang wrote:
> }
> } arr=(a b c)
> } arr[2,-1]=(z)
> } typeset arr # arr=(a z b c)
> 
> I would have to say that is a bug.  [1,-1] is handled as a special
> case, but it appears assignment botches other negative indices unless
> both the start and the end are negative.
> 
> Rather amazing that this has never come up before (and of course it
> can't help but appear immediately after a release is announced).

The assignment tests are weighted towards +=, because it was a new
feature.

Here are some tests for partial array assignment.  Ones for mixed
indices can be added when the patch is committed.  All of these are
still working.

Index: Test/A06assign.ztst
===================================================================
RCS file: /cvsroot/zsh/zsh/Test/A06assign.ztst,v
retrieving revision 1.6
diff -p -u -r1.6 A06assign.ztst
--- Test/A06assign.ztst	31 Aug 2010 19:32:57 -0000	1.6
+++ Test/A06assign.ztst	21 Dec 2010 09:59:29 -0000
@@ -7,6 +7,105 @@
 1:assign to association with odd no. of values
 ?(eval):2: bad set of key/value pairs for associative array
 
+# tests of array element assignment
+
+ array=(1 2 3 4 5)
+ array[1]=42
+ print $array
+0:Replacement of array element
+>42 2 3 4 5
+
+ array=(1 2 3 4 5)
+ array[1]=(42 43)
+ print $array
+0:Replacement of array element with array
+>42 43 2 3 4 5
+
+ array=(1 2 3 4 5)
+ array[1,2]=(42 43)
+ print $array
+0:Replacement of start of array
+>42 43 3 4 5
+
+ array=(1 2 3 4 5)
+ array[1,4]=(42 43)
+ print $array
+0:Replacement of start of array with shorter slice
+>42 43 5
+
+ array=(1 2 3 4 5)
+ array[1,6]=(42 43)
+ print $array
+0:Replacement of array by extending slice
+>42 43
+
+ array=(1 2 3 4 5)
+ array[3]=(42 43)
+ print $array
+0:Replacement of middle element with array
+>1 2 42 43 4 5
+
+ array=(1 2 3 4 5)
+ array[3,4]=(42 43 44)
+ print $array
+0:Replacement of slice in middle
+>1 2 42 43 44 5
+
+ array=(1 2 3 4 5)
+ array[7,8]=(42 43)
+ print $array
+ # check that [6] was left empty...
+ array[6]=41
+ print $array
+0:Appending by replacing elements off the end
+>1 2 3 4 5 42 43
+>1 2 3 4 5 41 42 43
+
+ array=(1 2 3 4 5)
+ array[-1]=42
+ print $array
+0:Replacement of last element of array, negative indices
+>1 2 3 4 42
+
+ array=(1 2 3 4 5)
+ array[-1]=(42 43)
+ print $array
+0:Replacement of last element of array with array, negative indices
+>1 2 3 4 42 43
+
+ array=(1 2 3 4 5)
+ array[-3,-2]=(42 43 44)
+ print $array
+0:Replacement of middle of array, negative indices
+>1 2 42 43 44 5
+
+ array=(1 2 3 4 5)
+ array[-5,-1]=(42 43)
+ print $array
+0:Replacement of entire array, negative indices
+>42 43
+
+ array=(1 2 3 4 5)
+ array[-7,-1]=(42 43)
+ print $array
+0:Replacement of more than entire array, negative indices
+>42 43
+
+ array=(1 2 3 4 5)
+ array[-7]=42
+ print $array
+0:Replacement of element off start of array.
+>42 1 2 3 4 5
+
+ array=(1 2 3 4 5)
+ array[-7]=42
+ array[-6]=43
+ print $array
+0:Replacement off start doesn't leave gaps.  Hope this is right.
+>43 1 2 3 4 5
+
+# TODO: mixed indices [-num,num] and [num,-num]
+
 # tests of var+=scalar
 
  s+=foo

-- 
Peter Stephenson <pws@xxxxxxx>            Software Engineer
Tel: +44 (0)1223 692070                   Cambridge Silicon Radio Limited
Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, UK


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