filesystem portability checks (Was: [boost] Any interest in adding unicode support to boost?)

From: Peter Dimov (pdimov_at_[hidden])
Date: 2004-10-25 13:10:53

Beman Dawes wrote:
> At 08:45 AM 10/25/2004, Peter Dimov wrote:
>> Beman Dawes wrote:
>>> At 01:10 PM 10/22/2004, Miro Jurisic wrote:
>>>
>>>> boost::fs, as far as I understand it, ran into the problem that it
>>>> was impossible to sidestep the invariant.
>>>
>>> No, rather than the error check was on by default. Some people want
>>> it off as the default.
>>
>> I interpret it a little differently: the "error" check provided no
>> value to users;
>
> That's true for some users, but not all users.

Certainly. Think of my statement as integrated over all possible users. Each 
user has his own unique needs, but it's still possible to form meaningful 
sentences that describe the general case.

>> in fact, it "provided" a negative value, which is why most prefer
>> "off by default".
>
> Only for the users who don't want to perform the check. For those
> that do want the check, it has a positive value.

I'm afraid I haven't been able to express my point well. My point was that 
if you focus on The Check, you'll only conclude that most users don't want 
The Check by default. This doesn't mean that most users don't want A Check 
by default; it just may not be The Check.

There is a spectrum of possibilities between Strictest Check and No Check 
which may contain the optimal default that provides just the right amount of 
portability checking.

> You could attribute the preference to the degree of portability
> required by the user's application's but I think it is more than
> that. Some people would rather be safe by default, while others
> would rather error checks only be applied if explicitly invoked.
> That seems like a personal preference to me.

I think that the main problem is that the current checks do not always 
signal errors. Errors are never a matter of personal preference, they are 
always part of a specification or dictated by external requirements.

Tolerating checks that typically produce a significant amount of false 
positives can be a matter of personal preference, of course. But it also 
depends on how such checks are implemented. I tolerate a relatively high 
degree of false positives in compiler warnings, but I'd rather not see a 
similar rate in compiler errors. I certainly wouldn't mind a filesystem 
_warning_ for nonportable paths, if we find a suitable delivery mechanism.