object identity and hashing

[castironpi at gmail.com]

On Feb 24, 7:58 pm, Jeff Schwab <j... at schwabcenter.com> wrote:
> castiro... at gmail.com wrote:
> > Can someone explain this?
>
> >>>> a= {}
>
> Create an empty dict and bind it to the name a.
>
> >>>> a[(3,)]= 0
>
> Set the key/value pair (3,):0 to the dict.
>
> >>>> (3,) in a
>
> Is (3,) one of the keys in the dict?
>
> > True
>
> Yes, it is.
>
> >>>> (3,) is (3,)
>
> Create two separate tuples (that happen to be equivalent).  Are they the
> same object?
>
> > False
>
> No, they are not.
>
> Every time you write (3,), you are potentially creating a new object.
> These objects have equal values (and hash codes), so they are
> interchangeable for purposes of keying a dict.

I see.  You stated,

> Is (3,) one of the keys in the dict?
>
> > True
>
> Yes, it is.

It isn't, but it does equal a key that's already in the dict.