Path Contexts

[ForNeVeR]

We'll need a file system API for virtual paths. Local path (#1) should implement the same API, so it should be possible to abstract over both kinds of paths.

The API should allow to:

• manipulate foreign paths, e.g. Windows paths on a Linux computer, and vice versa;
• introduce fully virtual file systems.

Currently, I am thinking of adding a new field of type IFileSystem or IPathContext to each of our path types: hopefully, this won't create too much overhead for their storage.

Default constructors would rely on a singleton instance for the current system, something like new LocalPath("foo") => new LocalPath("foo", LocalFileSystem.Instance).

There should be a way for the user to introduce custom path validation in constructor. For example, if they want to somehow avoid Windows paths on Linux and want to throw on new LocalPath(CustomContext, @"C:\Windows"), even though this path is valid.

TODO

• Introduce a field into all *Path types.
• Derive the path manipulation operations to the path context:
  • path separators,
  • behavior aspects such as Windows drives,
  • path validation in constructors (even for LocalPath that doesn't do any validation otherwise).
• Allow passing the context to path constructors.
• The constructors should delegate to some LocalPathContext.Instance by default (if nothing else is passed).
• LocalPathContext.Instance should be a writable field (for global custom override).
• Future enhancement request: allow ThreadLocal and/or AsyncLocal override for LocalPathContext, to avoid reliance on the global state.