http://www.reddit.com/r/programming/comments/8m6p0/dobbs_code_talk_its_not_always_nice_to_share/

On Fri, 22 May 2009 05:37:42 +1200, Walter Bright <newshound1@digitalmars.com> wrote:

> http://www.reddit.com/r/programming/comments/8m6p0/dobbs_code_talk_its_not_always_nice_to_share/


Should this change the way pure functions work. for example:

module test;

int i; //tls

pure void foo(int arg)
{
	i = arg;
}

void main()
{
	foo(2);
}


 Error: pure function 'foo' cannot access mutable static data 'i'

Tim Matthews wrote:
> Should this change the way pure functions work. for example:
> 
> module test;
> 
> int i; //tls
> 
> pure void foo(int arg)
> {
>     i = arg;
> }
> 
> void main()
> {
>     foo(2);
> }
> 
> 
>  Error: pure function 'foo' cannot access mutable static data 'i'

No. Pure functions cannot change global state, even if that global state is for one thread only.