The future of Python immutability

Stefan Behnel stefan_ml at behnel.de
Thu Sep 3 21:21:58 CEST 2009


Nigel Rantor wrote:
> 
> John Nagle wrote:
>>     Immutability is interesting for threaded programs, because
>> immutable objects can be shared without risk.  Consider a programming
>> model where objects shared between threads must be either immutable or
>> "synchronized" in the sense that Java uses the term.
>> Such programs are free of most race conditions, without much
>> programmer effort to make them so.
> 
> I disagree. They are not free of most race conditions, and it still
> takes a lot of effort. Where did you get this idea from? Have you been
> reading some Java primer that attempts to make it sound easy?

Read again what he wrote. In a language with only immutable data types
(which doesn't mean that you can't efficiently create modified versions of
a data container), avoiding race conditions is trivial. The most well known
example is clearly Erlang. Adding "synchronised" data structures to that
will not make writing race conditions much easier.

Stefan



More information about the Python-list mailing list