[Python-Dev] Re: Caching objects in memory

[Facundo Batista]

On 4/25/05, Guido van Rossum <gvanrossum at gmail.com> wrote:
> > I was in my second class of the Python workshop I'm giving here in one
> > Argentine University, and I was explaining how to think using
> > name/object and not variable/value.
> >
> > Using id() for being pedagogic about the objects, the kids saw that
> > id(3) was always the same, but id([]) not. I explained to them that
> > Python, in some circumstances, caches the object, and I kept them
> > happy enough.
> >
> > But I really don't know what objects and in which circumstances.
> 
> Aargh! Bad explanation. Or at least you're missing something:

Not really. It's easier for me to show that id(3) is always the same
and id([]) not, and let the kids see that's not so easy and you'll
have to look deeper if you want to know better.

If I did id(3) and id(500), then the difference would look more
subtle, and I would had to explain it longer. Remember, it was the
second day (2 hours per day).


> implementation is free to use caching. In practice, I believe ints
> between -5 and 100 are cached, and 1-character strings are often
> cached (but not always).

These are exactly my doubts, ;).

.    Facundo

Blog: http://www.taniquetil.com.ar/plog/
PyAr: http://www.python.org/ar/