Greeting.

In UML 1.5 spec (pg3-69) there's an xor-association which means there could
be only one association happen among a group of association at any one time.

e.g.
class 1 <-> class 2
class 1 <-> class 3
class 1 <-> class 4
//only one will be effective at any one point of time.

I would like to know how to put this in to code, if class2, class3, class4
is all different classes? My opinion is:

class1{
  class2 class_2
  class3 class_3
  class4 class_4
}
//among 3 association attribute, only one will be use at one point of time

- or -

class1{}

class1asso2 extends class1{
  class 2 class_2
}

class1asso3 extends class1{
  class3 class_3
}

class1asso4 extends class1{
  class4 class_4
}
//determine which class to instanciate in run-time

Or are there any better way to implement the xor-association?

Thank you.

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