On Apr 26, 1:48 am, John Nagle <na...@animats.com> wrote: > On 4/25/2012 5:01 PM, Steven D'Aprano wrote: > > > On Wed, 25 Apr 2012 13:49:24 -0700, Adam Skutt wrote: > > >> Though, maybe it's better to use a different keyword than 'is' though, > >> due to the plain English > >> connotations of the term; I like 'sameobj' personally, for whatever > >> little it matters. Really, I think taking away the 'is' operator > >> altogether is better, so the only way to test identity is: > >> id(x) == id(y) > > > Four reasons why that's a bad idea: > > > 1) The "is" operator is fast, because it can be implemented directly by > > the interpreter as a simple pointer comparison (or equivalent). > > This assumes that everything is, internally, an object. In CPython, > that's the case, because Python is a naive interpreter and everything, > including numbers, is "boxed". That's not true of PyPy or Shed Skin. > So does "is" have to force the creation of a temporary boxed object?
That's what C# does AFAIK. Java defines '==' as value comparison for primitives and '==' as identity comparison for objects, but I don't exactly know how one would do that in Python. Adam -- http://mail.python.org/mailman/listinfo/python-list
