# Render Converter Converter Source
# a bidirectional connection
+
+def cached(f):
+ name = f.__name__
+ def wrapper(self):
+ cache = self.cache
+ if cache is None:
+ return f(self)
+ if name not in cache:
+ cache[name] = (True, f(self))
+ return cache[name][1]
+ return wrapper
+
+class ElementError(Exception):
+ def __init__(self, message):
+ self.msg = message
+
+ def __str__(self):
+ return self.msg
+
class Element(object):
CHANGED_DEFAULT = 0 # initial "pull" state
CHANGED_ALL = 1 # really everything changed
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.clearCache()
+ self.cache = None
def connectDownstream(self, downstream):
self.downstream_elements.append(downstream)
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,))
# 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"
-
+
# 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)
if self.master == downstream:
# default action: push downstream
def changed(self, *args, **kwargs):
- self.clearCache()
+ self.cache = { }
self.downstream_elements.changed(*args, **kwargs)
- self.clearCache()
-
- def reconnectUpstream(self, new_upstream):
- assert self.source is not None
- self.source = new_upstream
-
- def clearCache(self):
self.cache = None
def setSuspend(self, 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)
def doSuspend(self, suspend):
pass
+
+ def destroy(self):
+ pass