Help, multidimensional list
Christopher Koppler
klapotec at chello.at
Sun Dec 28 09:55:19 EST 2003
On Sun, 28 Dec 2003 14:27:41 +0000, Crawley
<crawley.storm at IGetTooMuchSpamAsItIs.com> wrote:
>Im trying to create a list of lists and for some reason its not working:
>
>class Tile:
> _next = { 'n':None, 'ne':None, 'e':None, 'se':None, 's':None,
>'sw':None, 'w':None, 'nw':None }
>
>
>def blankGridCanvas( maxx, maxy ):
> grid = []
> for y in xrange( 0, maxy ):
> yline = []
> for x in xrange( 0, maxx ):
> t = Tile()
> if y != 0:
> t._next[ 'n' ] = grid[ y - 1 ][ x ]
> t._next[ 'n' ]._next[ 's' ] = t
>
> yline.append( t )
> grid.append( yline )
>
> for y in xrange( 0, maxy ):
> for x in xrange( 0, maxx ):
> print grid[ x ][ y ], grid[ x ][ y ]._next
> return grid
>
>now by my reconing this should be a list of lists with each element being
>an instance of Tile,
You only create a *class* Tile, and provide no way to create
*instances* of it - so much like with static variables in other
languages, you only have one 'instance' here. To be able to create
separate instances, you need a constructor in your class to
instantiate every instance, like so:
class Tile:
def __init__(self):
self._next = { 'n':None, 'ne':None, 'e':None, 'se':None,
's':None, 'sw':None, 'w':None, 'nw':None }
and some references being manipulated to point to each
>other. But strangly no, its actually a list of lists where each element is
>the SAME instance of Tile, so I change one, i change them ALL!
>
>Whats going on and how do I solve it?
Any gurus around can certainly much better explain what's going on and
why...
--
Christopher
More information about the Python-list
mailing list