[boost] Re: Re: Re: Re: [filesystem] status() if neitherfilenordirectory?

From: Beman Dawes (bdawes_at_[hidden])
Date: 2005-05-09 08:00:03

"Peter Dimov" <pdimov_at_[hidden]> wrote in message 
news:005f01c5547e$3e22aec0$6401a8c0_at_pdimov2...
> Beman Dawes wrote:
>> "Peter Dimov" <pdimov_at_[hidden]> wrote in message
>> news:00a201c55418$585bb2c0$6401a8c0_at_pdimov2...
>>> When a socket is thrown your way, you just run it by the list and
>>> conclude that no bit needs to be set.
>>
>> But that is about the same as having an other_flag, except that the
>> name is 0 instead of other_flag.
>
> You don't need a name because the user will never test for this category.
>
> if( status() & other_flag )
> {
>    // OK, so what do I do here?
> }
>
> The other categories have expectations attached, so testing for them makes 
> sense.

What you might do in the code above is report the fact that an "other" has 
been discovered, or execute a fallback procedure, or whatever.

>> Giving it a name makes it more obvious that a return from status()
>> may not have any of the other bits set.
>
> I, as a user, wouldn't rely on the "one bit rule" anyway. Idiomatic code 
> should work with any result from status(), as long as it makes sense. It 
> is reasonable to expect a future status() to return readable_flag and 
> writable_flag in addition to exists_flag (currently named !not_found_flag 
> to preserve the one bit rule.)

It is fine with me if status() returns multiple bits set, such as your 
writeable/readable example. But I prefer each of file type outcomes to have 
a specific name.

--Beman