If one types a[4:8:2] in Python, Python creates a slice object (call it s) with s.start = 4, s.stop = 8 and s.step = 2. It then passes this slice object to a's __getitem__ method. If one of the arguments is left out, it is filled with None: so the slice [:8:2] would have start None. However, if you don't have the second colon, instead of filling it with None, it fills start with a Python int 0 and stop with a Python int 2147483647 (which some of you may recognize as maxint). So a[:4] would call __getslice__(0, 4), or if that's not defined, __getitem__(slice(0, 4)). Similarly, if I write a[-2:8] it calls __getitem__(slice(a.__len__() - 2, 8, None)). Is there any way that I can distinguish between a[0:4] and a[:4] in writing __getitem__? Or more generally, get Python to construct a new style slice object when called with just two arguments? I want to overload the slice operator for p-adic fields and this is stymieing me (yes, that is how you spell stymieing: I just looked it up). David
--~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://sage.scipy.org/sage/ and http://modular.math.washington.edu/sage/ -~----------~----~----~----~------~----~------~--~---
