While trying to understand, what the "bself= self.aq_explicit" in "OFS.DTMLMethod.__call__" should do, I detected an unexpected behaviour: usually, this "bself" acquires implicitly from its container (though not from its context) More precisely: if "bself.aq_self" is itself an implicit acquisition wrapper, the "bself.aq_explicit" acquires implicitly from "bself.aq_self.aq_parent". The following Python module demonstrates the behaviour: ------------------------------------------------------- from Acquisition import Implicit class C(Implicit): pass b= C() b.i= 0 b.d= C() b.h= C() e_bd= b.d.aq_explicit try: e_bd.i print 'e_bd implicitly acquired i' except AttributeError: pass e_bhd= b.h.d.aq_explicit try: e_bhd.i print 'e_bhd implicitly acquired i' except AttributeError: pass ------------------------------------------------------- At first, I thought this were a bug. At second thought, however, it appears to be quite natural, though unexpected: if o is self.__of__(parent), then getattr(o.aq_explicit,k) = getattr(self,k).__of__(o) If "self" is an implicit wrapper itself, then acquisition may be used to look up "k". This implies, that the idiom <dtml-if "_.hasattr(o.aq_explicit,XXXX)"> cannot be used safely to test, whether "o" has attribute XXXX itself (rather than acquired it). We probably should have a standard function for this kind of test. Dieter