add NotifyList class

Author: cshorler

geomdl/_collections.py

@@ -0,0 +1,55 @@
+# callback handlers for list modification
+# https://stackoverflow.com/a/13259435/1162349
+
+import sys
+
+_pyversion = sys.version_info[0]
+
+def callback_method(func):
+    def notify(self,*args,**kwargs):
+        for _,callback in self._callbacks:
+            callback()
+        return func(self,*args,**kwargs)
+    return notify
+
+class NotifyList(list):
+    extend = callback_method(list.extend)
+    append = callback_method(list.append)
+    remove = callback_method(list.remove)
+    pop = callback_method(list.pop)
+    __delitem__ = callback_method(list.__delitem__)
+    __setitem__ = callback_method(list.__setitem__)
+    __iadd__ = callback_method(list.__iadd__)
+    __imul__ = callback_method(list.__imul__)
+
+    #Take care to return a new NotifyList if we slice it.
+    if _pyversion < 3:
+        __setslice__ = callback_method(list.__setslice__)
+        __delslice__ = callback_method(list.__delslice__)
+        def __getslice__(self,*args):
+            return self.__class__(list.__getslice__(self,*args))
+
+    def __getitem__(self,item):
+        if isinstance(item,slice):
+            return self.__class__(list.__getitem__(self,item))
+        else:
+            return list.__getitem__(self,item)
+
+    def __init__(self,*args):
+        list.__init__(self,*args)
+        self._callbacks = []
+        self._callback_cntr = 0
+
+    def register_callback(self,cb):
+        self._callbacks.append((self._callback_cntr,cb))
+        self._callback_cntr += 1
+        return self._callback_cntr - 1
+
+    def unregister_callback(self,cbid):
+        for idx,(i,cb) in enumerate(self._callbacks):
+            if i == cbid:
+                self._callbacks.pop(idx)
+                return cb
+        else:
+            return None
+