>>>>> zaur <szp...@gmail.com> (z) wrote: >z> On 29 авг, 16:45, zaur <szp...@gmail.com> wrote: >>> Python 2.6.2 (r262:71600, Apr 16 2009, 09:17:39) >>> [GCC 4.0.1 (Apple Computer, Inc. build 5250)] on darwin >>> Type "copyright", "credits" or "license()" for more information.>>> a=1 >>> >>> x=[a] >>> >>> id(a)==id(x[0]) >>> True >>> >>> a+=1 >>> >>> a >>> 2 >>> >>> x[0] >>> >>> 1 >>> >>> I thought that += should only change the value of the int object. But >>> += create new. >>> Is this intentional?
>z> As a result of this debate is not whether we should conclude that >z> there should be two types of integers in python: 1) immutable numbers, >z> which behave as constant value; 2) mutable numbers, which behave as >z> variable value? Numbers are immutable by nature (math). The number 3.14 remains 3.14 whatever you try to do with it. What you call an immutable number is in fact a container that contains a number. You can change the contents of the container, not by modifying the number in it but by replacing it with a different number. Python has sufficient mechanisms for creating these containers: lists, dictionaries, objects. If you think they are not good enough then write a new one in C. -- Piet van Oostrum <p...@cs.uu.nl> URL: http://pietvanoostrum.com [PGP 8DAE142BE17999C4] Private email: p...@vanoostrum.org -- http://mail.python.org/mailman/listinfo/python-list
