On 13 Sep 2008, at 09:37, John Vokey wrote:
Again, I ask, what have we gained by the ``new'' array features,
besides more brackets?
Maybe you're more of a hands on guy, and no explanation found on this
world will ever give you the same "aha" like trying it out yourself.
Barring that, here's a recent story on multidimensional arrays which
made me understand why they can help me:
I am constantly trying out systems for games, among other things
making maps. I have made a couple such test map stacks since spring,
and started with 2.9, then switched to the 3.0 beta. For those game
maps, I had chosen to use a 2d Cartesian coordinate system with square
fields, like a checkers board. Normally I'd start out with a fancy new
idea to scroll a map view, or how to speed certain animation things up
(As rev is horribly slow with setting more then 100 objects visuals at
the same time). So a common map might look like this in data:
Array[1,1] = 1
Array[1,2] = 1
Array[1,3] = 0
...
Array[100,100] = 0
Where 0 would be ocean, and 1 would be land. The problem of course
would arise if I added another map feature, like player token
positions, roads, cities, climate zones, whatever. Such an array might
then look like this (example is with items, normally i'd use lines):
Array[1,1] = 1, savannah, bottom, village
Array[1,2] = 1, desert, , , settler_1
Array[1,3] = 0,,,, ship_2
...
Array[100,100] = 0
Now to read/populate that I'd normally just do: "put "topleft" into
item 3 of Array[x,y]". Normally by now I'd have the idea to add plant
cover. I could add it as a fifth item, but that would not be the
correct place (should be before roads, after terraintype). The place
is important because it's easier to remember there, and because I have
no way to identify which item is what otherwise. To enter a new item
in between, I'd need to look at all my existing code, and change the
items around (with great chances of entering something wrong, or
overlooking a number). Now the same with multiple arrays (hierarchical
representation):
Array[1,1]
-----------[land] = 1
-----------[terrain] = savannah
-----------[road] = bottom
-----------[city] = village
Array[1,2]
-----------[land] = 1
-----------[terrain] = desert
-----------[unit] = settler_1
Array[1,3]
-----------[land] = 0
-----------[unit] = ship_2
...
Array[100,100]
-----------[land] = 0
Now this is self explanatory, just look at the keys and know what's
there. No need to depend on a mental ordered model, and adding other
information is dead simple, existing code that does not need that
information will just ignore additional keys (if it was done in
anticipation of that). So this form of data allows me to change my map
much easier, and therefore increase my productive output.
When I work more with this new data structure, I'll probably will find
many more very interesting things especially considering split and
combine, as well as union and merge.
Bjoernke
--
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