[Tutor] Re: When was interned strings dropped (and why)?

[hcohen2]

Isr Gish wrote:

>I find that only int's and string's have the same id when they are identical.
>But list's, tuple's and dictionary's have different id's even if theybare identical.
>
>P.s I'm using Python 2.3.2
>
>
>-----Original Message-----
>   >From: "Abel Daniel"<abli at freemail.hu>
>   >Sent: 1/30/04 7:56:01 AM
>   >To: "Daniel Ehrenberg"<littledanehren at yahoo.com>
>   >Cc: "pytutor"<tutor at python.org>
>   >Subject: [Tutor] Re: When was interned strings dropped (and why)?
>     >Daniel Ehrenberg writes:
>   >
>   >> Switch to 2.3. That's what I'm using and I don't have
>   >> that bug. Even identical tuples have the same id.
>   >
>   >Are you sure?
>   >
>   >Python 2.3.3 (#2, Dec 19 2003, 11:28:07) 
>   >[GCC 3.3.3 20031203 (prerelease) (Debian)] on linux2
>   >Type "help", "copyright", "credits" or "license" for more information.
>   >>>> t=(1,2)
>   >>>> tt=(1,2)
>   >>>> t is tt
>   >False
>   >>>> t == tt
>   >True
>   >>>> id(t)
>   >1075955500
>   >>>> id(tt)
>   >1075798540
>   >>>> ttt=t
>   >>>> id(ttt)
>   >1075955500
>   >>>> 
>   >
>   >Of course, if you define 'identical' as 'having the same id' then 'identical
>   >tuples have the same id', but you won't really be able to use this fact.
>   >
>   >-- 
>   >Abel Daniel
>   >
>   
>Good luck
>Isr
>
>
>_______________________________________________
>Tutor maillist  -  Tutor at python.org
>http://mail.python.org/mailman/listinfo/tutor
>
>  
>
Isr,

You say it, but on an earlier (buggier?) version it is not quite so clear.

 >>> sL = [12, 'abc', 'ghj']
 >>> aL = sL
 >>> id(sL)
134923940
 >>> id(aL)
134923940
 >>> id([12, 'abc', 'ghj'])
134939756
 >>> aL == sL
1
 >>> aL == [12, 'abc', 'ghj']
1

The lists 'aL' and 'sL' are stored in the exactly the same location,  
There actual value: [12, 'abc', 'ghj'] is found elsewhere.  However, 
both aL and sL are the same as the former though it resides elsewhere.

Try that and see what you get.

Herschel