On Aug 14, 5:45 am, Jean-Michel Pichavant <jeanmic...@sequans.com> wrote: > Emile van Sebille wrote: > > On 8/13/2009 3:17 PM dippim said... > >> I am new to Python and I have a question about descriptors. If I have > >> a class as written below, is there a way to use descriptors to be > >> certain that the datetime in start is always before the one in end? > > >> class foo(object): > >> def __init__(self,a = None,b = None) > >> self.start = a > >> self.end = b > > >> from datetime import datetime > >> c = datetime(2009,8,13,6,15,0) > >> d = datetime(2009,8,14,12,0,0) > >> afoo = foo(c,d) > > >> For instance, if the following code were run, I would like to instance > >> of foo to switch the start and end times. > > >> afoo.start = datetime(2010,8,13,6,15,0) > > >> I was thinking of using the __set__ descriptor to catch the assignment > >> and reverse the values if necessary, > > > why not... > > > class foo(object): > > def __init__(self,a = None,b = None) > > self.start = min(a,b) > > self.end = max(a,b) > > > Emile > > or > > class foo(object): > def __init__(self, start, end) > self.start = start > self.end = end > > Problem solved by design :o) > > JM
Emile and JM, Thanks for the response. However, these solution only work at instantiation. If I change the value of start or end after instantiation, then I can make start or end whatever I like without regard to order. -- http://mail.python.org/mailman/listinfo/python-list
