On Sun, Nov 10, 2013 at 2:21 AM, Roy Smith <r...@panix.com> wrote: > But, you missed the point of my question. You said that Python does > this "only when you ask for it". That implies it never interns strings > if you don't ask for it, which is clearly not true: > > $ python > Python 2.7.1 (r271:86832, Jul 31 2011, 19:30:53) > [...] >>>> x = "foo" >>>> y = "foo" >>>> x is y > True
Ah! Yes, that's true; literals are interned - I forgot that. But anything from an external source won't be, hence my example with reading in the contents of a file. > I think what you're trying to say is that there are several possible > interning policies: > > 1) Strings are never interned > > 2) Strings are always interned > > 3) Strings are optionally interned, at the discretion of the > implementation > > 4) The user may force a specific string to be interned by explicitly > requesting it. > > and that Pike implements #1, while Python implements #3 and #4. Pike implements #2, I presume that was a typo. And yes, the interning of literals falls under #3, while sys.intern() gives #4. Use of #1 would be restricted to languages with mutable strings, I would expect, for the same reason that Python tuples might be shared but lists won't be. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
