On Tue, 22 Nov 2005 20:37:40 +0100, Christoph Zwerschke <[EMAIL PROTECTED]> wrote:
>One implementation detail that I think needs further consideration is in >which way to expose the keys and to mix in list methods for ordered >dictionaries. > >In http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/107747 >the keys are exposed via the keys() method which is bad. It should be a >copy only, like for ordinary dicts (one comment also mentions that). > >In Foord/Larosa's odict, the keys are exposed as a public member which >also seems to be a bad idea ("If you alter the sequence list so that it >no longer reflects the contents of the dictionary, you have broken your >OrderedDict"). > >I think it would be probably the best to hide the keys list from the >public, but to provide list methods for reordering them (sorting, >slicing etc.). > >For instance: > >d1 = OrderedDict( (1, 11), (2, 12), 3, 13) ) > >d1[1:] ==> OrderedDict( (2, 12), 3, 13) ) > >d1[0] + d1[2] ==> OrderedDict( (1, 11), (3, 13) ) > >d1.reverse() ==> OrderedDict( (3, 13), (2, 12), 1, 11) ) > >d1.insert(1, (4, 14)) > ==> OrderedDict( (1, 11), (4, 14), (2, 12), 3, 13) ) > >etc. > >But no other way to directly manipulate the keys should be provided. > >>> from odictb import OrderedDict >>> d1 = OrderedDict([(1, 11), (2, 12), (3, 13)]) >>> d1 {1: 11, 2: 12, 3: 13} >>> d1[1:] {2: 12, 3: 13} >>> d1[0:1] + d1[2:3] {1: 11, 3: 13} >>> d1.reverse() >>> d1 {3: 13, 2: 12, 1: 11} >>> d1.insert(1, (4,14)) >>> d1 {3: 13, 4: 14, 2: 12, 1: 11} >>> d1.items() [(3, 13), (4, 14), (2, 12), (1, 11)] >>> d1.keys() [3, 4, 2, 1] >>> d1.values() [13, 14, 12, 11] >>> d1[1:2] {4: 14} >>> d1[-1:] {1: 11} Que mas? Regards, Bengt Richter -- http://mail.python.org/mailman/listinfo/python-list
