class Element:
def __init__(self):
self.downstream_elements = CList()
- self.upstream_elements = CList()
self.master = None
self.source = None
self.master = downstream
def connectUpstream(self, upstream):
- self.upstream_elements.append(upstream)
- self.source = upstream # for single-source elements (i.e., most of them.)
+ assert self.source is None
+ self.source = upstream
self.changed()
def connect(self, upstream):
self.connectUpstream(upstream)
upstream.connectDownstream(self)
+ # we disconnect from down to up
+ def disconnectAll(self):
+ # we should not disconnect from upstream if
+ # there are still elements depending on us.
+ assert len(self.downstream_elements) == 0, "there are still downstream elements left"
+ if self.source:
+ self.source.disconnectDownstream(self)
+
+ def disconnectDownstream(self, downstream):
+ self.downstream_elements.remove(downstream)
+ if self.master == downstream:
+ self.master = None
+
+ if len(self.downstream_elements) == 0:
+ self.disconnectAll()
+
# default action: push downstream
- def changed(self):
- self.downstream_elements.changed()
+ def changed(self, *args, **kwargs):
+ self.downstream_elements.changed(*args, **kwargs)
+
+ def reconnectUpstream(self, new_upstream):
+ assert self.source is not None
+ self.source = new_upstream