class ElementError(Exception):
def __init__(self, message):
- self.message = message
+ self.msg = message
def __str__(self):
- return self.message
+ return self.msg
class Element(object):
CHANGED_DEFAULT = 0 # initial "pull" state
CHANGED_SPECIFIC = 3 # second tuple will specify what exactly changed
CHANGED_POLL = 4 # a timer expired
+ SINGLE_SOURCE = True
+
def __init__(self):
self.downstream_elements = CList()
self.master = None
+ self.sources = [ ]
self.source = None
self.__suspended = True
self.cache = None
self.master = downstream
def connectUpstream(self, upstream):
- assert self.source is None
+ assert not self.SINGLE_SOURCE or self.source is None
+ self.sources.append(upstream)
+ # self.source always refers to the last recent source added.
self.source = upstream
self.changed((self.CHANGED_DEFAULT,))
assert len(self.downstream_elements) == 0, "there are still downstream elements left"
# Sources don't have a source themselves. don't do anything here.
- if self.source is not None:
- self.source.disconnectDownstream(self)
+ for s in self.sources:
+ s.disconnectDownstream(self)
+
+ if self.source:
# sources are owned by the Screen, so don't destroy them here.
self.destroy()
+ self.source = None
+ self.sources = [ ]
def disconnectDownstream(self, downstream):
self.downstream_elements.remove(downstream)
self.downstream_elements.changed(*args, **kwargs)
self.cache = None
- def reconnectUpstream(self, new_upstream):
- assert self.source is not None
- self.source = new_upstream
-
def setSuspend(self, suspended):
changed = self.__suspended != suspended
if not self.__suspended and suspended:
self.doSuspend(0)
self.__suspended = suspended
- if self.source is not None and changed:
- self.source.checkSuspend()
+ if changed:
+ for s in self.sources:
+ s.checkSuspend()
suspended = property(lambda self: self.__suspended, setSuspend)