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Subject: RE: [PATCH 1/7] rust: file: add Rust abstraction for `struct file`
From:   Alice Ryhl <aliceryhl@google.com>
To:     david.laight@aculab.com
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David Laight <David.Laight@ACULAB.COM> writes:
> > > I don't know about Rust namespacing, but in other languages, how you
> > > have to especify namespaces tend to be ***far*** more verbose than
> > > just adding an O_ prefix.
> > 
> > In this case we already have the `flags` namespace, so I thought about
> > just dropping the `O_` prefix altogether.
> 
> Does rust have a 'using namespace' (or similar) so that namespace doesn't
> have to be explicitly specified each time a value is used?
> If so you still need a hint about which set of values it is from.
> 
> Otherwise you get into the same mess as C++ class members (I think
> they should have been .member from the start).
> Or, worse still, Pascal and multiple 'with' blocks.

Yes.

You can import it with a use statement. For example:

use kernel::file::flags::O_RDONLY;
// use as O_RDONLY

or:

use kernel::file::flags::{O_RDONLY, O_WRONLY, O_RDWR};
// use as O_RDONLY

or:

use kernel::file::flags::*;
// use as O_RDONLY

If you want to specify a namespace every time you use it, then it is
possible: (But often you wouldn't do that.)

use kernel::file::flags;
// use as flags::O_RDONLY

or:

use kernel::file;
// use as file::flags::O_RDONLY

or:

use kernel::file::flags as file_flags;
// use as file_flags::O_RDONLY

And you can also use the full path if you don't want to add a `use`
statement.

Alice