On Jun 19, 5:13 am, Faheem Mitha <[EMAIL PROTECTED]> wrote: > On Wed, 18 Jun 2008 12:57:44 -0700 (PDT), Lie <[EMAIL PROTECTED]> wrote: > > On Jun 19, 2:26 am, Faheem Mitha <[EMAIL PROTECTED]> wrote: > >> Hi everybody, > > >> I was wondering if anyone can explain this. My understanding is that 'is' > >> checks if the object is the same. However, in that case, why this > >> inconsistency for short strings? I would expect a 'False' for all three > >> comparisons. This is reproducible across two different machines, so it is > >> not just a local quirk. I'm running Debian etch with Python 2.4.4 (the > >> default). > >> Thanks, Faheem. > > >> In [1]: a = '--' > > >> In [2]: a is '--' > >> Out[2]: False > > >> In [4]: a = '-' > > >> In [5]: a is '-' > >> Out[5]: True > > >> In [6]: a = 'foo' > > >> In [7]: a is 'foo' > >> Out[7]: True > > > Yes, this happens because of small objects caching. When small > > integers or short strings are created, there are possibility that they > > might refer to the same objects behind-the-scene. Don't rely on this > > behavior. > > Yes, but why is '-' and 'foo' cached, and not '--'? Do you know what > the basis of the choice is? > Faheem.
Yes, but we're already warned not to rely on it since the basis of what may be cached and what-not might be arbitrary. Personally, I'd not delve deeply into them, they aren't a reliable behavior. -- http://mail.python.org/mailman/listinfo/python-list
