[EMAIL PROTECTED] wrote: > Steve Holden wrote: > >>[EMAIL PROTECTED] wrote: >> >>>I have a problem. I'm writing a simulation program with a number of >>>mechanical components represented as objects. When I create instances >>>of objects, I need to reference (link) each object to the objects >>>upstream and downstream of it, i.e. >>> >>>supply = supply() >>>compressor = compressor(downstream=combustor, upstream=supply) >>>combuster = combuster(downstream=turbine, upstream=compressor) >>>etc. >>> >>>the problem with this is that I reference 'combustor' before is it >>>created. If I swap the 2nd and 3rd lines I get the same problem >>>(compressor is referenced before creation). >>> >>> >>>aargh!!! any ideas on getting around this? >>> >> >>Yes. You are building a generic data structure, so you shouldn't really >>be trying to store individual objects in variables like that. You need a >>data structure that's appropriate to your problem. >> >>For example, you could consider storing them in a list, so you have >> >>components = [supply(), compressor(), combuster()] >> >>Then components[n] is upstream of components[n-1] and downstream of >>components[n+1]. > > > Unfortunately, if he wanted to make the topology more complicated, for > instance having two components downstream, it would be much more > cumbersome to inherit the list object and implement this. > I quite agree. That was why I began with "for example". > >>In short, your thinking about data representation might need to become a >>little more sophisticated. > > > That sounds a little arrogant. sorry! > Hmm, maybe it does, in which case I apologise retrospectively. But all the more appropriate suggestions have definitely been pointing that way.
Circuit design is a complex problem. I was merely trying to indicate that the naive approach was unlikely to succeed. Sure enough, a few posts later the OP admitted that there needed to be sub-chains for sub-circuits, and so on. regards Steve -- Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC/Ltd http://www.holdenweb.com Skype: holdenweb http://holdenweb.blogspot.com Recent Ramblings http://del.icio.us/steve.holden -- http://mail.python.org/mailman/listinfo/python-list
