Question about iterator_traits<>::pointer questions

[Johannes Schaub (litb)]

I wonder what the heck iterator_traits<>:ointer is good for? The Standard
says it should be the type of "it->". What's that!? When is "pointer" ever
useful in an algorithm?

 

[Howard Hinnant]

I wonder what the heck iterator_traits<>:ointer is good for? The Standard
says it should be the type of "it->". What's that!? When is "pointer" ever
useful in an algorithm?

A non-built-in pointer is useful for creating a proxy-pointer in
process-shared memory. So making pointer generic helps generic code
work correctly whether it is dealing with built-in pointers or proxy
pointers (into shared memory). Iterator adaptors for example will
need to query an iterator's pointer type so that they can write their
own operator->().

-Howard