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From: Beman Dawes (bdawes_at_[hidden])
Date: 2002-09-17 10:31:38

At 10:12 AM 9/17/2002, Peter Dimov wrote:

>I've been trying to understand your point of view but I still don't see
>you avoid the current directory with the above.
>Consider the case (assume POSIX for clarity) where the user input is

Yes, but that isn't a portability problem because on an operating system
that doesn't support the concept of relative path the user would have to
enter an absolute path.

In other words, the program is portable, but the user input is system
specific, and that is exactly the functionality we want.

>Your base path is relative, and as such, it inherently depends on the
>current directory. In order for the program to function as intended,
>must be interpreted as relative to initial_directory() even if the
>directory changes while the program is running, but the library does not
>provide a way to do that.

That's a strong argument for providing some additional functionality, but
exactly what should the semantics be? That's been the hold up all along.

Let's see. Here is the code we would like to write:

    path p( argv[1], system_specific );
    if ( ) p = initial_directory() << p;

Say the user input is "foo" - should be true.

Say the user input is "/foo" (or "c:/foo" on Windows) - then p.x() should
be false.

So far, so good. Here comes the problem: what if on Windows the user input
is "/foo". That needs to return false.

So if xxx() is named relative(), to have it return false is very
misleading. That is what has been hanging me up.

How about incomplete() as a name?

    path p( argv[1], system_specific );
    if ( p.incomplete() ) p = initial_directory() << p;

>In effect, the library works as intended only if the current directory
>doesn't change.

> But if the current directory is assumed to never change, it
>is no longer "evil" to provide a way to access it, as it is a global

Exactly. That was the rationale behind the initial_directory() semantics.

Thanks for the help on this; it has been bothersome.


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