pure or not pure?

[guslay]

Janice Caron Wrote:

> On 09/04/2008, Steven Schveighoffer <schveiguy at yahoo.com> wrote:

> 
> >  as an example of a pure function that takes a pointer to mutable data, but
> >  doesn't use the data, i.e. this doesn't ever read or write heap data:
> >
> >  pure char *add(char * c, int n) { return c + n;}
> 
> Oooh - now that's an interesting one. That one's got me foxed. My
> instinct says it should be disallowed, but I can't quite put my finger
> on why. I'm gonna have to think about that one some more.
> 

As long as you stick to pointer arithmetic and don't dereference c, it is pure.

Will it be allowed, that's pure speculation ;)