Pure, const, etc

[Koroskin Denis]

On Sat, 21 Jun 2008 03:53:24 +0400, bearophile <bearophileHUGS at lycos.com>  
wrote:

> Stuff D will do:
> http://lwn.net/Articles/285332/
>
> Bye,
> bearophile

Nice. But can't see why strlen is pure (in the article):
int __attribute__((pure)) strlen(const char* string) {
	return /* you know what */;
}

char* someString = "Hello";
int len1 = strlen(someString);
someString[4] = 0;		// guess what is it now? :)
int len2 = strlen(someString);	// input is *not* changed

One thing they lack is an invariant type.
And the main problem is that it is not standardazed, so it is not portable  
across compilers.