On 2018-08-07 23:31, Mark Wieder via use-livecode wrote:
On 08/07/2018 02:21 PM, Mark Waddingham via use-livecode wrote:
However, the engine treats arrays which have all integer (string) keys
starting at one and are dense (i.e. the number of elements == max(all
keys)) from ones that aren't.
There should have been a 'differently' in there.
Not sure how to interpret that. If I create
repeat with i=1 to 10
put i into tArray[i]
end repeat
to make a 'special' array and then
delete variable tArray[3]
does that take it out of the 'special' category?
Yes - unless the array's first key is 1, and it then has all integer
keys up to and including its number of elements then it is not
considered a sequence array.
i.e. [1], [3], [5] - not a sequence
[2], [3], [4] - not a sequence
[1], [2], [3] - a sequence
The specialness is quite restricted - however such arrays:
1) are ordered when used with 'repeat for each element' *not* repeat
for each key:
repeat for each element tElement in tSeqArray
... tElement will first be [1], then [2], ... then [n] ...
end repeat
2) can be used as a sequence of keys to traverse in [] - e.g.
put tArray[tSeqArray] == tArray[tSeqArray[1]]...[tSeqArray[2]]
3) admit a more efficient representation in arrayEncode - they are
encoded as 'sequences', so the engine does not emit the keys - instead
it just emits a sequence of values [1], [2], ..., [n]... Which saves
some space.
Warmest Regards,
Mark.
--
Mark Waddingham ~ m...@livecode.com ~ http://www.livecode.com/
LiveCode: Everyone can create apps
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