On Nov 20, 3:09 pm, Terry Reedy <tjre...@udel.edu> wrote: > Joshua Bronson wrote: > > Anyone have any other feedback? For instance, is offering the __call__ > > syntax for the inverse mapping wonderful or terrible, or maybe both? > > Terrible ;-) > > Use standard subscripting with slices, and only that, to both get and set. > > Let m[4] == m[4:] == 'abc' # m[4:] is suggested alternative addition > Then m[:'abc'] == 4 > > m[4:] passes slice(4,None,None) to __getitem__ > m[:'abc'] passes slice(None,'abc',None) > > It just happens that dict items and slices use the same notation, but > they do, so take advantage of that. In fact, to emphasize the symmetry > of the bijective map, consider disallowing m[key] as ambiguous and > require m[key:], along with m[:key] to access and set. > > Note that m[slice(1,2,3):] passes slice(slice(1, 2, 3), None, None), so > this approach does not even prevent using slices as keys/values. > > In __setitem__, m[a:b] which passes slice(a,b,None) would have to be an > error. In __getitem__, it could either be a error or return True/False > depending on whether the pair is in the map. But this depends on whether > __contains__ only tests keys or is modified to test pairs. > > Terry Jan Reedy
absolutely genius. implemented in the latest version: http://bitbucket.org/jab/toys/src/tip/bijection.py thank you for the terrific idea! -- http://mail.python.org/mailman/listinfo/python-list
