[boost] Re: Re: [filesystem] Operations predicates

From: Beman Dawes (bdawes_at_[hidden])
Date: 2005-05-04 20:16:11

"Rob Stewart" <stewart_at_[hidden]> wrote in message 
news:200505041425.j44EPnrb027885_at_weezy.balstatdev.susq.com...

>   status_flag status(path const &, int * error = 0);
>
> It is simpler from an implementation standpoint, but I don't
> think it is simpler from the caller's perspective.  Since the
> argument is defaulted, the compiler will offer no help to ensure
> that you get and inspect the error number.
>
> Returning a type with the flags and error number together means
> that you always get the error number and can inspect it.  Whether
> you use any schemes to ensure that the caller inspects a non-zero
> error number -- such as asserting in the destructor if an
> "inspected" flag isn't set -- is another matter.

That seems like a convincing argument.

We could use std::pair<> or tuple<>, but I'm included to put the two in a 
struct with meaningful member names.

--Beman