def set_referent(asker, rep, new_value, s):
import updates, dictionaries
return asker.ask_tail(updates.apply_update(
updates.set_field(
fields.compose(bindings(), dictionaries.image(s)),
new_value
),
rep
))
def update(self, change, v, repr_change=None):
if repr_change is None:
repr_change = updates.lift(change)
default_repr_change = True
else:
default_repr_change = False
if v.id in self.internal:
internal = self.internal[v.id]
#if we are updating stale information...
#apply the update, but not any representation change
#(if info is stale, probably just a representation change...)
if v.id != self.current[internal].id:
if change.head == updates.trivial.head:
return True
else:
repr_change = updates.lift(change)
self.updates[internal] = updates.compose(self.updates[internal], change)
self.current[internal] = convert.unquote(
self,
self.ask_firmly(updates.apply_update(
repr_change,
representations.quote(self.current[internal])
))
)
self.changed[internal] = True
return True
else:
#FIXME think more about how this propagation ought to work
#it seems like something is going oddly w.r.t levels of abstraction
#also should I propagate back across field accesses? I don't know...
#also this whole thing seems kind of like a mess, I don't expect it to work consistently
def propagate_back(s):
if s.head == term.because.head:
return propagate_back(s['operation'])
elif s.head == term.explain.head:
return propagate_back(s['operation']) or propagate_back(s['prior'])
elif s.head == term.accessing.head:
if change.head == updates.trivial.head:
parent = s['term']
binding = s['binding']
return self.update(
updates.trivial(),
parent,
repr_change=updates.apply_to_field(
representations.referent_of(T.from_str(binding)),
repr_change
).explain("tracing backwards from [v]", v=v)
)
else:
return False
elif s.head == askers.answering.head:
Q = s['Q']
if Q.head == fields.get_field.head:
parent = Q['object']
field = Q['field']
return self.update(
updates.apply_to_field(field, change),
parent,
repr_change=updates.apply_to_field(updates.lift_field(field), repr_change)
)
elif Q.head == convert.convert.head:
previous = Q['value']
return self.update(
change,
previous,
repr_change=None
)
return False
return propagate_back(v.source)
