hi, i also tried to make a simple example of this situation and after a while i noticed the following behavior of the class A:
--- (defpclass A() ((id :initarg :id :accessor id-of :index t) (points-to :accessor points-to :associate (A pointed-by) :many-to-many t) (pointed-by :accessor pointed-by :associate (A points-to) :many-to-many t))) --- the association index of the slots points-to and pointed-by is the same. so i redefined the class: --- (defpclass A() ((id :initarg :id :accessor id-of :index t) (points-to :accessor points-to :associate (A points-to) :many-to-many t) (pointed-by :accessor pointed-by :associate (AnotherClass points-to) :many-to-many t))) --- afterwards i made 2 instances of the new definition and checked the indices and they were not equal. finally i defined the original class A and made the directed associations, it worked. there's also the original file attached, with the exact program sequence. regards lukas > Hi, > > we came across a (to us) surprising behavior of the association code in > elephant-unstable: If we generate associations between instances of the > same > class, then elephant forces these associations to be symmetric. That means > we > cannot use association slots to implement directed graphs. > > For example, the attached program is supposed to set up a "diamond"; We'd > therefore expect the following output: > > Node A: > successors: (B C) > predecessors: () > Node B: > successors: (D) > predecessors: (A) > Node C: > successors: (D) > predecessors: (A) > Node D: > successors: () > predecessors: (B C) > > However, elephant makes both the successor and the predecessor slot hold > always the same references: > > Node A: > successors: (B C) > predecessors: (B C) > Node B: > successors: (A D) > predecessors: (A D) > Node C: > successors: (A D) > predecessors: (A D) > Node D: > successors: (B C) > predecessors: (B C) > > Is this by design or is this a bug? Or did we simply use the association > API > incorrectly? > > Regards > > Christoph > > -- > FH Worms - University of Applied Sciences > Fachbereich Informatik / Telekommunikation > Erenburgerstr. 19, 67549 Worms, Germany > _______________________________________________ > elephant-devel site list > elephant-devel@common-lisp.net > http://common-lisp.net/mailman/listinfo/elephant-devel
directed_graph_works.lisp
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