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
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