Whether this file exists.
Whether this file exists. Reading a non-existent file may fail
Name of the file/writer, including extension
Name of the file/writer, including extension
Path of the file, including everything.
Path of the file, including everything. Unique if possible (used for lookup).
URI for this virtual file
URI for this virtual file
Optionally returns an implementation-dependent "version" token.
Optionally returns an implementation-dependent "version" token. Versions are compared with ==. If non-empty, a different version must be returned when the content changes. It should be equal if the content has not changed, but it is not mandatory. Such a token can be used by caches: the file need not be read and processed again if its version has not changed.
A base class for simple in-memory mutable virtual files.