Duncan Booth wrote: > Steve Holden <[EMAIL PROTECTED]> wrote: > > >>Absolutely correct. It would be more interesting to discuss how the >>output from these statements varied between (say) CPython, Jython and >>Iron Python. At the moment the discussion is indeed about insignificant >>implementation trivia. > > > CPython seems to collapse identical float values if they are in the same > compilation unit: > > >>>>x = 2. >>>>y = 2. >>>>x is y > > False > >>>>x = 2.; y = 2. >>>>x is y > > True > >>>>y = [2., 2.] >>>>y[0] is y[1] > > True > > IronPython doesn't collapse them even when they are in expression: > > IronPython 1.0.60816 on .NET 2.0.50727.42 > Copyright (c) Microsoft Corporation. All rights reserved. > >>>>x = 2. >>>>y = 2. >>>>x is y > > False > >>>>x = 2.; y = 2. >>>>x is y > > False > >>>>y = [2., 2.] >>>>y[0] is y[1] > > False > > JPython seems to behave in a similar manner to CPython: > > Python command console - JPython 2.1 > > >>>>x = 2. >>>>y = 2. >>>>x is y > > 0 > > >>>>x = 2.; y = 2. >>>>x is y > > 1 > > >>>>y = [2., 2.] >>>>y[0] is y[1] > > 1 > > > > Sorry, I don't have a more recent Jython implementation to hand to complete > the comparison.
Perfectly all right: you make the point very well that the behavior is an implementation artifact and not a language feature. regards Steve -- Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC/Ltd http://www.holdenweb.com Skype: holdenweb http://holdenweb.blogspot.com Recent Ramblings http://del.icio.us/steve.holden -- http://mail.python.org/mailman/listinfo/python-list
