questions

From: Fabien Baldacci (baldacci_at_vivaldi.emi.u-bordeaux.fr)
Date: 12/31/03 

Date: 31 Dec 2003 15:07:49 GMT

hi i have a few questions:

1.i'm working on a database, and i'm storing objects in different hashtables. each object must be able to give a list of other objects that belong to it(i put a slot in each class for this) , for example the object "Computer Science"(class 'major') must have the list of all the students of this major (class 'student'). now my question: is it better to put the objects('students' for exmaple) directly on a list, or put only their keys (the reference in the hashtable) on the list?
Or,generaly does it take a lot of memory if we store already existing objects on a list, or does it only make new pointers on the same (eq) objects?

2.can we give an object as an optional argument to a generic function(and a method), if yes how?

3.how can i define a new slot (in a new file) for an already existing class, defined in another file?

looking forward your answers
and
thank U