# $Id: ListItemCollection.py,v 1.9.2.1 2006/08/09 09:07:12 marcusva Exp $ # # Copyright (c) 2004-2005, Marcus von Appen # All rights reserved. # Redistribution and use in source and binary forms, with or without # modification, are permitted provided that the following conditions are met: # # * Redistributions of source code must retain the above copyright notice, # this list of conditions and the following disclaimer. # * Redistributions in binary form must reproduce the above copyright notice, # this list of conditions and the following disclaimer in the documentation # and/or other materials provided with the distribution. # # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" # AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE # ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE # LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR # CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF # SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS # INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN # CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) # ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE # POSSIBILITY OF SUCH DAMAGE. """List item collection.""" from UserList import UserList from ListItem import ListItem class ListItemCollection (UserList): """ListItemCollection (items=None) -> ListItemCollection An collection class for ListItem objects. The ListItemCollection wraps a list object and limits it to the abstract ListItem class type, so that it is guaranteed, that the collection only contains a specific object type. It adds a notification slot 'list_changed', to which a method or function can be connected either by assigning the attribute directly or using the set_list_changed() method. The slot'ed callback will be invoked, whenever the list contents change. The signature of the function or method to connect has to get one argument, which will be the ListItemCollection. class Example: ... def list_callback (self, collection): ... collection.list_changed = object_example.list_callback collection.set_list_changed (object_example.list_callback) The ListItemCollection also adds a notification slot 'item_changed', to which a method or function can be connected using (again) the attribute directly or the set_item_changed() method. The callback will be invoked, whenever a ListItem of the collection changes and calls the callback. The signature of the function or method to connect has to get one argument, which will be the ListItem, which invoked it. class Example: ... def item_callback (self, item): ... collection.item_changed = object_example.item_callback collection.set_item_changed (object_example.item_callback) The ListItemCollection does support the usual list operations such as appending, insertion and removal using indices, slicing,the count() and len() methods and the list iterator. Attributes: length - Amount of the items attached to the ListItemCollection. list_changed - Slot to connect a method to, which will be called whenever the contents of the ListItemCollection change. item_changed - Slot to connect a method to, which will be called whenever an item of the ListItemCollection changes. """ def __init__ (self, items=None): if items != None: invalid = filter (lambda x: not isinstance (x, ListItem), items) if len (invalid) != 0: raise ValueError ("items must contain only ListItem objects") UserList.__init__ (self, items) self._length = 0 # Notifier slots. self._listchanged = None self._itemchanged = None def append (self, item): """L.append (...) -> None Appends a ListItem to the end of the ListItemCollection Raises a TypeError, if the passed argument does not inherit from the ListItem class. """ if not isinstance (item, ListItem): raise TypeError ("item must inherit from ListItem") UserList.append (self, item) self._length += 1 if item.collection != self: item.collection = self if self.list_changed: self.list_changed (self) def count (self, item): """L.count (...) -> int Returns the number of occurences of the ListItem. Raises a TypeError, if the passed argument does not inherit from the ListItem class. """ if not isinstance (item, ListItem): raise TypeError ("item must inherit from ListItem") UserList.count (self, item) def insert (self, index, item): """L.insert (...) -> None Inserts the ListItem before index. Raises a TypeError, if the passed item argument does not inherit from the ListItem class. """ if not isinstance (item, ListItem): raise TypeError ("item must inherit from ListItem") UserList.insert (self, index, item) self._length += 1 if item.collection != self: item.collection = self if self.list_changed: self.list_changed (self) def remove (self, item): """L.remove (...) -> None Removes the first occurance of item from the ListItemCollection. """ UserList.remove (self, item) item.collection = None self._length -= 1 if self.list_changed: self.list_changed (self) def sort (self, cmp=None, key=None, reverse=False): """L.sort (...) -> None Stable in place sort for the ListItemCollection. """ UserList.sort (self, cmp, key, reverse) if self.list_changed: self.list_changed (self) def set_list_changed (self, method): """L.set_list_changed (...) -> None Connects a method to invoke, when the collection changes. Raises a TypeError, if the passed argument is not callable. """ if method and not callable (method): raise TypeError ("method must be callable") self._listchanged = method def set_item_changed (self, method): """L.set_item_changed (...) -> None Connects a method to invoke, when an item of the collection changes. Raises a TypeError, if the passed argument is not callable. """ if method and not callable (method): raise TypeError ("method must be callable") self._itemchanged = method def __setitem__ (self, index, item): """L.__setitem__ (index, item) -> L[index] = item Raises a TypeError, if the passed item argument does not inherit from the ListItem class. """ if not isinstance (item, ListItem): raise TypeError ("item must inherit from ListItem") old = UserList.__getitem__ (self, index) # Remove the old ListItem. old.collection = None del old # Set the new one. UserList.__getitem__ (self, index, item) if item.collection != self: item.collection = self if self.list_changed: self.list_changed (self) def __len__ (self): """L.__len__ () -> len (L) """ return self._length def __setslice__ (self, i, j, collection): """L.__setslice__ (i, j, collection) -> L[i:j] = collection Raises a TypeError, if the passed collection argument does not inherit from the ListItemCollection class. """ if not isinstance (collection, ListItemCollection): raise TypeError ("collection must inherit from ListItemCollection") old = UserList.__getslice__ (self, i, j) UserList.__setslice__ (self, i, j, collection[:]) new = UserList.__getslice__ (self, i, j) # Clean up the old ones. for item in old: item.collection = None self._length -= 1 del item # Set the relations for the new ones. for item in new: item.collection = self self._length += 1 if self.list_changed: self.list_changed (self) length = property (lambda self: self._length, doc = "Amount of the attached items.") list_changed = property (lambda self: self._listchanged, lambda self, var: self.set_list_changed (var), doc = "Notifier slot for collection changes.") item_changed = property (lambda self: self._itemchanged, lambda self, var: self.set_item_changed (var), doc = "Notifier slot for item changes.")