1.79 class identity

An identity expresses that Attribute A of object O1 equals Attribute B of object O2. It is the most basic relation object.

1.79.1 Instance variables

identity <-> from: selector1=name

Attribute at the specified side of the constraint object. For normal bi-directional relations, both constrained objects should define both send- and get-behaviour with the specified name.

If a constraint object is used as a propagator (see‘constraint identity->initialise’), get-behaviour on one side and send-behaviour on the other suffices.

identity <-> to: selector2=name

Inherits description from: identity-from

1.79.2 Send methods

identity ->backwards: from=object, to=object

Performs a get-operation on to using the selector identity<-to, followed by a send-operation on from using the send identity<-from.

identity ->create: from=object*, to=object*

Update after instantiation.

identity ->forwards: from=object, to=object

Performs a get-operation on from using the selector identity<-from, followed by a send-operation on to using the send identity<-to.

identity ->initialise: selector1=name, selector2=[name]

Create a relation defining

``Attribute selector1 of `constraint <-from` equals
Attribute selector2 of `constraint <-to`''

If the second selector is not specified is defaults to the first.